

<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.icumed.com/role/AcquisitionAndStrategicTransactionDetails" xlink:href="icui-20160930.xsd#AcquisitionAndStrategicTransactionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/AcquisitionAndStrategicTransactionDetails1" xlink:href="icui-20160930.xsd#AcquisitionAndStrategicTransactionDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/AcquisitionAndStrategicTransactionDetails2" xlink:href="icui-20160930.xsd#AcquisitionAndStrategicTransactionDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/AcquisitionAndStrategicTransactionNotes" xlink:href="icui-20160930.xsd#AcquisitionAndStrategicTransactionNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/AcquisitionAndStrategicTransactionTables" xlink:href="icui-20160930.xsd#AcquisitionAndStrategicTransactionTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/BasisOfPresentation" xlink:href="icui-20160930.xsd#BasisOfPresentation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/BasisOfPresentationBasisOfPresentationDetails" xlink:href="icui-20160930.xsd#BasisOfPresentationBasisOfPresentationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/CommitmentsAndContingencies" xlink:href="icui-20160930.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/CommitmentsAndContingenciesCommitmentsDetails" xlink:href="icui-20160930.xsd#CommitmentsAndContingenciesCommitmentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/CondensedConsolidatedBalanceSheets" xlink:href="icui-20160930.xsd#CondensedConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:href="icui-20160930.xsd#CondensedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:href="icui-20160930.xsd#CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/CondensedConsolidatedStatementsOfIncome" xlink:href="icui-20160930.xsd#CondensedConsolidatedStatementsOfIncome" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/DeiDocument" xlink:href="icui-20160930.xsd#DeiDocument" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/FairValueMeasurement" xlink:href="icui-20160930.xsd#FairValueMeasurement" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/FairValueMeasurementDetails" xlink:href="icui-20160930.xsd#FairValueMeasurementDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/FairValueMeasurementDetails1" xlink:href="icui-20160930.xsd#FairValueMeasurementDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/FairValueMeasurementDetails2" xlink:href="icui-20160930.xsd#FairValueMeasurementDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/FairValueMeasurementTables" xlink:href="icui-20160930.xsd#FairValueMeasurementTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/GainOnSaleOfBuildingDetails" xlink:href="icui-20160930.xsd#GainOnSaleOfBuildingDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/GainOnSaleOfBuildingNotes" xlink:href="icui-20160930.xsd#GainOnSaleOfBuildingNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/GainOnSaleOfBuildingTables" xlink:href="icui-20160930.xsd#GainOnSaleOfBuildingTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/IncomeTaxes" xlink:href="icui-20160930.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/IncomeTaxesEffectiveTaxRateDetails" xlink:href="icui-20160930.xsd#IncomeTaxesEffectiveTaxRateDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/Inventories" xlink:href="icui-20160930.xsd#Inventories" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/InventoriesDetails" xlink:href="icui-20160930.xsd#InventoriesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/InventoriesTables" xlink:href="icui-20160930.xsd#InventoriesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/InvestmentSecurities" xlink:href="icui-20160930.xsd#InvestmentSecurities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/InvestmentSecuritiesDetails" xlink:href="icui-20160930.xsd#InvestmentSecuritiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/InvestmentSecuritiesDetails1" xlink:href="icui-20160930.xsd#InvestmentSecuritiesDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/InvestmentSecuritiesDetails2" xlink:href="icui-20160930.xsd#InvestmentSecuritiesDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/InvestmentSecuritiesTables" xlink:href="icui-20160930.xsd#InvestmentSecuritiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/LegalSettlement" xlink:href="icui-20160930.xsd#LegalSettlement" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/LegalSettlementLegalSettlementChargeDetails" xlink:href="icui-20160930.xsd#LegalSettlementLegalSettlementChargeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/MajorCustomer" xlink:href="icui-20160930.xsd#MajorCustomer" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/MajorCustomerDetails" xlink:href="icui-20160930.xsd#MajorCustomerDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/NetIncomePerShare" xlink:href="icui-20160930.xsd#NetIncomePerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/NetIncomePerShareDetails" xlink:href="icui-20160930.xsd#NetIncomePerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/NetIncomePerShareDetails1" xlink:href="icui-20160930.xsd#NetIncomePerShareDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/NetIncomePerShareTables" xlink:href="icui-20160930.xsd#NetIncomePerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/NewAccountingPronouncements" xlink:href="icui-20160930.xsd#NewAccountingPronouncements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/NewAccountingPronouncementsNewAccountingPronouncementsDetails" xlink:href="icui-20160930.xsd#NewAccountingPronouncementsNewAccountingPronouncementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/PropertyAndEquipment" xlink:href="icui-20160930.xsd#PropertyAndEquipment" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/PropertyAndEquipmentDetails" xlink:href="icui-20160930.xsd#PropertyAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/PropertyAndEquipmentTables" xlink:href="icui-20160930.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/RestructuringChargesDetails" xlink:href="icui-20160930.xsd#RestructuringChargesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/RestructuringChargesDetails1" xlink:href="icui-20160930.xsd#RestructuringChargesDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/RestructuringChargesNotes" xlink:href="icui-20160930.xsd#RestructuringChargesNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/RestructuringChargesTables" xlink:href="icui-20160930.xsd#RestructuringChargesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/SubsequentEventsDetails" xlink:href="icui-20160930.xsd#SubsequentEventsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/SubsequentEventsNotes" xlink:href="icui-20160930.xsd#SubsequentEventsNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/SubsequentEventsTables" xlink:href="icui-20160930.xsd#SubsequentEventsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/TreasuryStock" xlink:href="icui-20160930.xsd#TreasuryStock" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/TreasuryStockDetails" xlink:href="icui-20160930.xsd#TreasuryStockDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.icumed.com/role/TreasuryStockTables" xlink:href="icui-20160930.xsd#TreasuryStockTables" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/AcquisitionAndStrategicTransactionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_7B826C2065D2EEC0DCB7025AF8D0F59E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_99F248C111A098F7FCF9025AF8D06AEC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_7B826C2065D2EEC0DCB7025AF8D0F59E" xlink:to="loc_us-gaap_SubsequentEventTable_99F248C111A098F7FCF9025AF8D06AEC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_2F9B06B7EBD34E26CF6F025AF8D0792B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_99F248C111A098F7FCF9025AF8D06AEC" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_2F9B06B7EBD34E26CF6F025AF8D0792B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_E4DFA8584A43C8081713025AF8D0BE56_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_2F9B06B7EBD34E26CF6F025AF8D0792B" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_E4DFA8584A43C8081713025AF8D0BE56_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_E4DFA8584A43C8081713025AF8D0BE56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_2F9B06B7EBD34E26CF6F025AF8D0792B" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_E4DFA8584A43C8081713025AF8D0BE56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_8171A1B8D1937C2D7029025AF8D03192" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_E4DFA8584A43C8081713025AF8D0BE56" xlink:to="loc_us-gaap_SubsequentEventMember_8171A1B8D1937C2D7029025AF8D03192" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_438AA40BD4EC3DB647A7025AF8D036CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_7B826C2065D2EEC0DCB7025AF8D0F59E" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_438AA40BD4EC3DB647A7025AF8D036CD" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_Numberofsharesissuedasconsideration" xlink:label="loc_icui_Numberofsharesissuedasconsideration_43BAE8C4C0DC6348F4D3025AF8D0C53F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_7B826C2065D2EEC0DCB7025AF8D0F59E" xlink:to="loc_icui_Numberofsharesissuedasconsideration_43BAE8C4C0DC6348F4D3025AF8D0C53F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/AcquisitionAndStrategicTransactionDetails1" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/AcquisitionAndStrategicTransactionDetails2" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/AcquisitionAndStrategicTransactionNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/AcquisitionAndStrategicTransactionTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/BasisOfPresentation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/BasisOfPresentationBasisOfPresentationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/CommitmentsAndContingenciesCommitmentsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_2311C17EB3F2C6444A3D025B4A88CD55" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50E74039ED2187431E8B025B4A87CD0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2311C17EB3F2C6444A3D025B4A88CD55" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50E74039ED2187431E8B025B4A87CD0A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_E583C6E1316AB9015276025B4A8791CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_50E74039ED2187431E8B025B4A87CD0A" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_E583C6E1316AB9015276025B4A8791CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_31EFCED3012D8D47BDF5025B4A871C79_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_E583C6E1316AB9015276025B4A8791CD" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_31EFCED3012D8D47BDF5025B4A871C79_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_31EFCED3012D8D47BDF5025B4A871C79" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_E583C6E1316AB9015276025B4A8791CD" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_31EFCED3012D8D47BDF5025B4A871C79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_42B4BDFB2BF12BF6D5A7025B4A88D894" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_31EFCED3012D8D47BDF5025B4A871C79" xlink:to="loc_us-gaap_SubsequentEventMember_42B4BDFB2BF12BF6D5A7025B4A88D894" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_2F4CBF327F4DD7FB6007025B4A889502" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2311C17EB3F2C6444A3D025B4A88CD55" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_2F4CBF327F4DD7FB6007025B4A889502" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_Numberofsharesissuedasconsideration" xlink:label="loc_icui_Numberofsharesissuedasconsideration_7236B0C39CC61980816F025B4A884A47" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2311C17EB3F2C6444A3D025B4A88CD55" xlink:to="loc_icui_Numberofsharesissuedasconsideration_7236B0C39CC61980816F025B4A884A47" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_SeniorSecuredCreditFacility" xlink:label="loc_icui_SeniorSecuredCreditFacility_E6EC3B82D46E8B4B5658025B4A896758" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2311C17EB3F2C6444A3D025B4A88CD55" xlink:to="loc_icui_SeniorSecuredCreditFacility_E6EC3B82D46E8B4B5658025B4A896758" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_TermLoan" xlink:label="loc_icui_TermLoan_52C1F782017735585895025B4A897D18" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2311C17EB3F2C6444A3D025B4A88CD55" xlink:to="loc_icui_TermLoan_52C1F782017735585895025B4A897D18" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_02079E44612607665D46025B4A894013" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_2311C17EB3F2C6444A3D025B4A88CD55" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_02079E44612607665D46025B4A894013" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_4FC60CC3675D3F4967E3E94AEDCADA4E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_StatementTable_4FC60CC3675D3F4967E3E94AEDCADA4E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_C9DEE65AD57340128513E94AEDCAFCB2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_4FC60CC3675D3F4967E3E94AEDCADA4E" xlink:to="loc_us-gaap_StatementScenarioAxis_C9DEE65AD57340128513E94AEDCAFCB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_42E8672D6D355653D8EFE94AEDCA70BE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_C9DEE65AD57340128513E94AEDCAFCB2" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_42E8672D6D355653D8EFE94AEDCA70BE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_42E8672D6D355653D8EFE94AEDCA70BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_C9DEE65AD57340128513E94AEDCAFCB2" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_42E8672D6D355653D8EFE94AEDCA70BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:to="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_07EDEB6742B8865317A4E94AEDCA06A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_07EDEB6742B8865317A4E94AEDCA06A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesCurrent_8408046644C24E48B8ADE94AEDCAFC53" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesCurrent_8408046644C24E48B8ADE94AEDCAFC53" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashCashEquivalentsAndShortTermInvestments" xlink:label="loc_us-gaap_CashCashEquivalentsAndShortTermInvestments_0D53807E7F64659DF56DE94AEDCA2600" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_CashCashEquivalentsAndShortTermInvestments_0D53807E7F64659DF56DE94AEDCA2600" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_A5BCD0C40A9E96F58027E94AEDCA2ADA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_A5BCD0C40A9E96F58027E94AEDCA2ADA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_1CC5953FCF523B7E0123E94AEDCAC355" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_InventoryNet_1CC5953FCF523B7E0123E94AEDCAC355" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrepaidTaxes" xlink:label="loc_us-gaap_PrepaidTaxes_317C5BAEB8EF1D5C51A9E94AEDCA65D8" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_PrepaidTaxes_317C5BAEB8EF1D5C51A9E94AEDCA65D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_992F1F3FD986CE9DD1BEE94AEDCA0618" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_992F1F3FD986CE9DD1BEE94AEDCA0618" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrent" xlink:label="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrent_42B4AFE076E857C45260E94AEDCA4E56" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrent_42B4AFE076E857C45260E94AEDCA4E56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_3FAEA390A5CEF7CF10ADE94AEDCACE36" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_6AAC84E117159DD068F7E94AEDCAD38D" xlink:to="loc_us-gaap_AssetsCurrent_3FAEA390A5CEF7CF10ADE94AEDCACE36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_2E1F9491D053D29CF6CEE94AEDCADB55" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_2E1F9491D053D29CF6CEE94AEDCADB55" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesNoncurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent_AF7484A196D24056E82EE94AEDCAFC9A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent_AF7484A196D24056E82EE94AEDCAFC9A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_C5D51ACFC13FBFEBAC7BE94AEDCA7B64" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:to="loc_us-gaap_Goodwill_C5D51ACFC13FBFEBAC7BE94AEDCA7B64" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_B30556E9F4864E1AD887E94AEDCA5081" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_B30556E9F4864E1AD887E94AEDCA5081" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsNetNoncurrent" xlink:label="loc_us-gaap_DeferredTaxAssetsNetNoncurrent_05F27B9269C5213E5283E94AEDCA692D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:to="loc_us-gaap_DeferredTaxAssetsNetNoncurrent_05F27B9269C5213E5283E94AEDCA692D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_9468778655D081D49707E94AEDCAAF94" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_4D7A90FA466F7CA58A42E94AEDCAF25C" xlink:to="loc_us-gaap_Assets_9468778655D081D49707E94AEDCAAF94" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_0DC5D76F1163BB3665D4E94AEDCAE26D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_0DC5D76F1163BB3665D4E94AEDCAE26D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_5F22D489010DF88F02C6E94AEDCA43E4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0DC5D76F1163BB3665D4E94AEDCAE26D" xlink:to="loc_us-gaap_AccountsPayableCurrent_5F22D489010DF88F02C6E94AEDCA43E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_CD53C65CACC4159D2D65E94AEDCA5576" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0DC5D76F1163BB3665D4E94AEDCAE26D" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_CD53C65CACC4159D2D65E94AEDCA5576" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_3138BA962B91D524D1ECE94AEDCA6A20" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_0DC5D76F1163BB3665D4E94AEDCAE26D" xlink:to="loc_us-gaap_LiabilitiesCurrent_3138BA962B91D524D1ECE94AEDCA6A20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent" xlink:label="loc_us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent_DE18454EC47099B57800E94AEDCA85A8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:to="loc_us-gaap_LiabilitiesOtherThanLongtermDebtNoncurrent_DE18454EC47099B57800E94AEDCA85A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_9A626B28C4F63B2E2625E94AEDCAE13B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesNoncurrent_9A626B28C4F63B2E2625E94AEDCAE13B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_B37717C9E122BD47D756E94AEDCA87AD" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_B37717C9E122BD47D756E94AEDCA87AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_72618C62430A332C0237E94AEDCAB6B2" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:to="loc_us-gaap_CommitmentsAndContingencies_72618C62430A332C0237E94AEDCAB6B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConvertiblePreferredStockNonredeemableOrRedeemableIssuerOptionValue" xlink:label="loc_us-gaap_ConvertiblePreferredStockNonredeemableOrRedeemableIssuerOptionValue_F925B056DE5495D834A6E94AEDCAD105" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:to="loc_us-gaap_ConvertiblePreferredStockNonredeemableOrRedeemableIssuerOptionValue_F925B056DE5495D834A6E94AEDCAD105" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_AA2EE549E00F42B781FEE94AEDCA1319" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:to="loc_us-gaap_CommonStockValue_AA2EE549E00F42B781FEE94AEDCA1319" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_3206D995C457052D6E0FE94AEDCA015E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_3206D995C457052D6E0FE94AEDCA015E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockValue" xlink:label="loc_us-gaap_TreasuryStockValue_AE245956BD3AABBCF5B4E94AEDD43392" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:to="loc_us-gaap_TreasuryStockValue_AE245956BD3AABBCF5B4E94AEDD43392" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_9AF1D7603227EC5C8831E94AEDD44191" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_9AF1D7603227EC5C8831E94AEDD44191" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_56BA9E52D4AE8D69FF33E94AEDD4AB22" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_56BA9E52D4AE8D69FF33E94AEDD4AB22" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_41F58AC5E75EAEBEF185E94AEDD45310" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_24480A25F6C5FB87B421E94AEDCA1A6F" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_41F58AC5E75EAEBEF185E94AEDD45310" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_A833E4EAD30412011D0DE94AEDD4B498" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_316FF39D49314C28329CE94AEDCA2477" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_A833E4EAD30412011D0DE94AEDD4B498" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_D446928AB1AA86D7BFABE94AEDD4B448" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_D446928AB1AA86D7BFABE94AEDD4B448" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_26B11371666D3CDF53D0E94AEDD4AE5E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_26B11371666D3CDF53D0E94AEDD4AE5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_C159B6212F8FE7859FD3E94AEDD4D762" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_C159B6212F8FE7859FD3E94AEDD4D762" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_5A2ECC02DD2C2C84C520E94AEDD4D4FE" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_PreferredStockSharesIssued_5A2ECC02DD2C2C84C520E94AEDD4D4FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_818522C16DA4DDD3E5D2E94AEDD40C4F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_818522C16DA4DDD3E5D2E94AEDD40C4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_D82F01B736397C48C989E94AEDD4C95B" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_D82F01B736397C48C989E94AEDD4C95B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_B2411565D2C1B7E3337DE94AEDD4A9EC" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_B2411565D2C1B7E3337DE94AEDD4A9EC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_08DFA7AFDD412275BC61E94AEDD46794" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_CommonStockSharesIssued_08DFA7AFDD412275BC61E94AEDD46794" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_8CCE3C8197E84ADFAB0EE94AEDD41562" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_8CCE3C8197E84ADFAB0EE94AEDD41562" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_D5C6B6D91BA49E9F2E2AE94AEDD4CE0A" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_3C614C12BFBA49FB0DCEE94AEDCAB07D" xlink:to="loc_us-gaap_TreasuryStockShares_D5C6B6D91BA49E9F2E2AE94AEDD4CE0A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_D91C9C94567FA855D4A4E8845239190D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_StatementTable_D91C9C94567FA855D4A4E8845239190D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_5DDA337B570C0E163B5AE88452390708" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_D91C9C94567FA855D4A4E8845239190D" xlink:to="loc_us-gaap_StatementScenarioAxis_5DDA337B570C0E163B5AE88452390708" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_6A9DD9DC6F6EA93F7D51E8845239ECF1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_5DDA337B570C0E163B5AE88452390708" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_6A9DD9DC6F6EA93F7D51E8845239ECF1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_6A9DD9DC6F6EA93F7D51E8845239ECF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_5DDA337B570C0E163B5AE88452390708" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_6A9DD9DC6F6EA93F7D51E8845239ECF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_8B108B8C5849B080A0E3E88452394A2B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_8B108B8C5849B080A0E3E88452394A2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_99ECD3C03D602CF8419EE8845239DA3E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_8B108B8C5849B080A0E3E88452394A2B" xlink:to="loc_us-gaap_ProfitLoss_99ECD3C03D602CF8419EE8845239DA3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_8B108B8C5849B080A0E3E88452394A2B" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_0EA8B46368C0DAF17B62E88452395561" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_0EA8B46368C0DAF17B62E88452395561" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_4874F6136590AC3EFDE6E8845239175A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_4874F6136590AC3EFDE6E8845239175A" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_ProvisionForWarrantyAndReturns" xlink:label="loc_icui_ProvisionForWarrantyAndReturns_083E86ACC29E694ADC00E8845239BA06" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_icui_ProvisionForWarrantyAndReturns_083E86ACC29E694ADC00E8845239BA06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_4471F7BC621F36405B0EE88452393E98" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_us-gaap_ShareBasedCompensation_4471F7BC621F36405B0EE88452393E98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_64FEC0C8823213B8280EE88452391585" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_64FEC0C8823213B8280EE88452391585" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentIncomeAmortizationOfPremium" xlink:label="loc_us-gaap_InvestmentIncomeAmortizationOfPremium_D00E9065B7ECB13734ECE88452395BB0" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_us-gaap_InvestmentIncomeAmortizationOfPremium_D00E9065B7ECB13734ECE88452395BB0" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_Bargainpurchasegainnoncashaddback" xlink:label="loc_icui_Bargainpurchasegainnoncashaddback_CD197866EA07F3593D60E8845239E1FB" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_icui_Bargainpurchasegainnoncashaddback_CD197866EA07F3593D60E8845239E1FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherNoncashExpense" xlink:label="loc_us-gaap_OtherNoncashExpense_04B24ABC1C4EDC67EA0AE88452397831" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_us-gaap_OtherNoncashExpense_04B24ABC1C4EDC67EA0AE88452397831" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_961EA8835C73627FC3A0E88452396F70" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_9711C928DF221327BA4FE8845239F7C1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_9711C928DF221327BA4FE8845239F7C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_B06E1F265E0977B7A701E88452398B63" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_B06E1F265E0977B7A701E88452398B63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_29553D4B348CD1DA2612E884523933C1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_29553D4B348CD1DA2612E884523933C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_D1E1E135BA010DDFEDB2E8845239A961" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_D1E1E135BA010DDFEDB2E8845239A961" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_648D4145E0EC4313796AE8845239D20A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_648D4145E0EC4313796AE8845239D20A" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_IncreaseDecreaseinincometaxesincludingexcesstaxbenefitsanddeferredincometaxes" xlink:label="loc_icui_IncreaseDecreaseinincometaxesincludingexcesstaxbenefitsanddeferredincometaxes_21C325ECE2233B5051D9E8845239E368" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_41AA5623998270253D3DE88452395595" xlink:to="loc_icui_IncreaseDecreaseinincometaxesincludingexcesstaxbenefitsanddeferredincometaxes_21C325ECE2233B5051D9E8845239E368" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_2983CF8BC2B75282DD15E8845239ED8E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_8B108B8C5849B080A0E3E88452394A2B" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_2983CF8BC2B75282DD15E8845239ED8E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_BE37FF15CFD7B324DD89E8845239ACD7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_BE37FF15CFD7B324DD89E8845239ACD7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_BC4D266A4DD729101E9CE88452399AE2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_BC4D266A4DD729101E9CE88452399AE2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_15D50379D14645B5E808E8845239652C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_15D50379D14645B5E808E8845239652C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_2A4AED95B3211DFD6E77E8845239168B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_2A4AED95B3211DFD6E77E8845239168B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireMarketableSecurities" xlink:label="loc_us-gaap_PaymentsToAcquireMarketableSecurities_DD3D435A8E22DF1493B6E8845239012A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:to="loc_us-gaap_PaymentsToAcquireMarketableSecurities_DD3D435A8E22DF1493B6E8845239012A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities" xlink:label="loc_us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities_6D795AE8FCA753146AB2E8845239F53D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:to="loc_us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities_6D795AE8FCA753146AB2E8845239F53D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_F7B598BF842DCD82AB3DE8845239FB0B" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_8B24F14F1616064A129AE88452394EDD" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_F7B598BF842DCD82AB3DE8845239FB0B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_8A61D5C1BF0F6D26EC54E8845239BC7B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_8A61D5C1BF0F6D26EC54E8845239BC7B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_9EB721F04B7FFFECAD84E88452399401" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_8A61D5C1BF0F6D26EC54E8845239BC7B" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_9EB721F04B7FFFECAD84E88452399401" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromStockPlans" xlink:label="loc_us-gaap_ProceedsFromStockPlans_B0C068582F7941101F51E884523929D8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_8A61D5C1BF0F6D26EC54E8845239BC7B" xlink:to="loc_us-gaap_ProceedsFromStockPlans_B0C068582F7941101F51E884523929D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_052C496B82E04C94E939E884523993EA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_8A61D5C1BF0F6D26EC54E8845239BC7B" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_052C496B82E04C94E939E884523993EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_09AF3D51F09455904BBEE88452393E0B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_8A61D5C1BF0F6D26EC54E8845239BC7B" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_09AF3D51F09455904BBEE88452393E0B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_61CE7F57C37BC11167C9E8845239C600" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_61CE7F57C37BC11167C9E8845239C600" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_33834C13F9A36B900270E8845239AA03" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_33834C13F9A36B900270E8845239AA03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_78D7D621182FF4EB52A3E8845239AAA9" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_78D7D621182FF4EB52A3E8845239AAA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NoncashInvestingAndFinancingItemsAbstract" xlink:label="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_3EDE4713FBE1456C23C1E88452395A98" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F3EC84A3B44AD2EA15DDE88452399276" xlink:to="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_3EDE4713FBE1456C23C1E88452395A98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_8DEC4A7E01B089D4AC56E88452399868" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashInvestingAndFinancingItemsAbstract_3EDE4713FBE1456C23C1E88452395A98" xlink:to="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_8DEC4A7E01B089D4AC56E88452399868" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_EB734C3C332DC064CA7EE884524DB740" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_93657B47CBB33C755517E884524DD94F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_EB734C3C332DC064CA7EE884524DB740" xlink:to="loc_us-gaap_StatementTable_93657B47CBB33C755517E884524DD94F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_CCDE34D51774DA239BA7E884524D3576" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_93657B47CBB33C755517E884524DD94F" xlink:to="loc_us-gaap_StatementScenarioAxis_CCDE34D51774DA239BA7E884524D3576" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_56EC9661266FB276396EE884524D060E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_CCDE34D51774DA239BA7E884524D3576" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_56EC9661266FB276396EE884524D060E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_56EC9661266FB276396EE884524D060E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_CCDE34D51774DA239BA7E884524D3576" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_56EC9661266FB276396EE884524D060E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_C8F8648731DBED46F195E884524D481A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_EB734C3C332DC064CA7EE884524DB740" xlink:to="loc_us-gaap_ProfitLoss_C8F8648731DBED46F195E884524D481A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_2808A6B40D63BEB475BAE884524DF2B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_EB734C3C332DC064CA7EE884524DB740" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_2808A6B40D63BEB475BAE884524DF2B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_103DD83008ED1ACD79A3E884524DE364" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_2808A6B40D63BEB475BAE884524DF2B5" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_103DD83008ED1ACD79A3E884524DE364" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_1B7FE0A19AB9678FAE07E884524DE24A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_2808A6B40D63BEB475BAE884524DF2B5" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_1B7FE0A19AB9678FAE07E884524DE24A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTax_EB7647B32E3144730855E884524DB013" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_EB734C3C332DC064CA7EE884524DB740" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTax_EB7647B32E3144730855E884524DB013" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/CondensedConsolidatedStatementsOfIncome" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_9AAB9C4DAB2B89079879E94B54DE5B5B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_StatementTable_9AAB9C4DAB2B89079879E94B54DE5B5B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_A3AA45982784EA1C4883E94B54DE09A6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_9AAB9C4DAB2B89079879E94B54DE5B5B" xlink:to="loc_us-gaap_StatementScenarioAxis_A3AA45982784EA1C4883E94B54DE09A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_7C28F7A26CBFD51435F5E94B54DE6C97_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementScenarioAxis_A3AA45982784EA1C4883E94B54DE09A6" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_7C28F7A26CBFD51435F5E94B54DE6C97_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_7C28F7A26CBFD51435F5E94B54DE6C97" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementScenarioAxis_A3AA45982784EA1C4883E94B54DE09A6" xlink:to="loc_us-gaap_ScenarioUnspecifiedDomain_7C28F7A26CBFD51435F5E94B54DE6C97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_FF5C4B40431DD629DDD7E94B54DEA011" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_RevenuesAbstract_FF5C4B40431DD629DDD7E94B54DEA011" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:label="loc_us-gaap_SalesRevenueGoodsNet_38D67A5D338C1694B9F0E94B54DE9118" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_FF5C4B40431DD629DDD7E94B54DEA011" xlink:to="loc_us-gaap_SalesRevenueGoodsNet_38D67A5D338C1694B9F0E94B54DE9118" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherSalesRevenueNet" xlink:label="loc_us-gaap_OtherSalesRevenueNet_C8A148D3BCCEDD33299AE94B54DED4E3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_FF5C4B40431DD629DDD7E94B54DEA011" xlink:to="loc_us-gaap_OtherSalesRevenueNet_C8A148D3BCCEDD33299AE94B54DED4E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_D2E9443604A0962AB9F5E94B54DFC0E4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_FF5C4B40431DD629DDD7E94B54DEA011" xlink:to="loc_us-gaap_Revenues_D2E9443604A0962AB9F5E94B54DFC0E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostOfGoodsSold" xlink:label="loc_us-gaap_CostOfGoodsSold_355FFD1EE94D361CB81EE94B54DF6978" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_CostOfGoodsSold_355FFD1EE94D361CB81EE94B54DF6978" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_25AB7E2A40FF86C9F0F5E94B54DF6878" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_GrossProfit_25AB7E2A40FF86C9F0F5E94B54DF6878" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_3D9C8A3D768E01A9DAD5E94B54DFE7E4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_3D9C8A3D768E01A9DAD5E94B54DFE7E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_2BEA951EFDD8FBE07717E94B54DFE8DE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_2BEA951EFDD8FBE07717E94B54DFE8DE" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_Restructuringandstrategictransaction" xlink:label="loc_icui_Restructuringandstrategictransaction_B5467FEE3ABA068D31B1E94B54DF327C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:to="loc_icui_Restructuringandstrategictransaction_B5467FEE3ABA068D31B1E94B54DF327C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets1" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_535F47FC0E788112AAE1E94B54DF07F6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_535F47FC0E788112AAE1E94B54DF07F6" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_Legalsettlementsincludingamountsawardedinadisputeandchargesamountspaidoutinaseparatedispute." xlink:label="loc_icui_Legalsettlementsincludingamountsawardedinadisputeandchargesamountspaidoutinaseparatedispute._F5B0DA6814B902C4919CE94B54DFB2B1" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:to="loc_icui_Legalsettlementsincludingamountsawardedinadisputeandchargesamountspaidoutinaseparatedispute._F5B0DA6814B902C4919CE94B54DFB2B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_91B981CBB4ED703EE90CE94B54DFD999" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_D846E359ECA9EEDAFEE8E94B54DFDAA1" xlink:to="loc_us-gaap_OperatingExpenses_91B981CBB4ED703EE90CE94B54DFD999" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_B9985DB928E19227890FE94B54DF9132" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_OperatingIncomeLoss_B9985DB928E19227890FE94B54DF9132" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationBargainPurchaseGainRecognizedAmount" xlink:label="loc_us-gaap_BusinessCombinationBargainPurchaseGainRecognizedAmount_9509C44A69CD1604310CE94B54DFFDC4" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_BusinessCombinationBargainPurchaseGainRecognizedAmount_9509C44A69CD1604310CE94B54DFFDC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_86A80B9A9D93FE2DA3E9E94B54DFAB98" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_86A80B9A9D93FE2DA3E9E94B54DFAB98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_02B2D8A516EABD0DA967E94B54E58666" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_02B2D8A516EABD0DA967E94B54E58666" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_BADFE7BA0C1FB716A551E94B54E5ADD2" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_BADFE7BA0C1FB716A551E94B54E5ADD2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_3C5387CF8315F5DCAD4DE94B54E5CBB9" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_ProfitLoss_3C5387CF8315F5DCAD4DE94B54E5CBB9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_6D90CECCB6469601A6F5E94B54E59A42" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_EarningsPerShareAbstract_6D90CECCB6469601A6F5E94B54E59A42" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_E0DC20E54EC8B01F9589E94B54E59AC8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_6D90CECCB6469601A6F5E94B54E59A42" xlink:to="loc_us-gaap_EarningsPerShareBasic_E0DC20E54EC8B01F9589E94B54E59AC8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_F8AC7D8F7E4A13AF6761E94B54E5CD9E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_6D90CECCB6469601A6F5E94B54E59A42" xlink:to="loc_us-gaap_EarningsPerShareDiluted_F8AC7D8F7E4A13AF6761E94B54E5CD9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C738DDE2248AC0F213EAE94B54E567C6" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_F1750D26E691BAD0487BE94B54DEF59E" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C738DDE2248AC0F213EAE94B54E567C6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_A1ECC66E5BCA1C20277BE94B54E50C3A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C738DDE2248AC0F213EAE94B54E567C6" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_A1ECC66E5BCA1C20277BE94B54E50C3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_D37215A5FF1A2C8A96D4E94B54E584F1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_C738DDE2248AC0F213EAE94B54E567C6" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_D37215A5FF1A2C8A96D4E94B54E584F1" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/DeiDocument" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityInformationLineItems" xlink:label="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntitiesTable" xlink:label="loc_dei_EntitiesTable_E97B21A4F8BABFACD330B40ECB50BCB6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_EntitiesTable_E97B21A4F8BABFACD330B40ECB50BCB6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_dei_LegalEntityAxis_8C0B352EDBAA1C1225DBB40ECB508A73" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_E97B21A4F8BABFACD330B40ECB50BCB6" xlink:to="loc_dei_LegalEntityAxis_8C0B352EDBAA1C1225DBB40ECB508A73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_0B0865757769F1478380B40ECB50B4B7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_8C0B352EDBAA1C1225DBB40ECB508A73" xlink:to="loc_dei_EntityDomain_0B0865757769F1478380B40ECB50B4B7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityDomain" xlink:label="loc_dei_EntityDomain_0B0865757769F1478380B40ECB50B4B7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_8C0B352EDBAA1C1225DBB40ECB508A73" xlink:to="loc_dei_EntityDomain_0B0865757769F1478380B40ECB50B4B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityRegistrantName" xlink:label="loc_dei_EntityRegistrantName_159A0489A614ACD4F236B40ECB50910C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_EntityRegistrantName_159A0489A614ACD4F236B40ECB50910C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey_4C7D87DBF30B465E0AD8B40ECB50D38A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_EntityCentralIndexKey_4C7D87DBF30B465E0AD8B40ECB50D38A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentType" xlink:label="loc_dei_DocumentType_5D4B2822F87CCA018392B40ECB50B9B2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_DocumentType_5D4B2822F87CCA018392B40ECB50B9B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_568EA09519E8E8F2DBDBB40ECB50B635" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_DocumentPeriodEndDate_568EA09519E8E8F2DBDBB40ECB50B635" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag_66468260ED51B8F5039EB40ECB5094CD" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_AmendmentFlag_66468260ED51B8F5039EB40ECB5094CD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_dei_CurrentFiscalYearEndDate_D524A3F2E8E3DC874E4DB40ECB5067EF" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_CurrentFiscalYearEndDate_D524A3F2E8E3DC874E4DB40ECB5067EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCurrentReportingStatus" xlink:label="loc_dei_EntityCurrentReportingStatus_296A80D5A4D0C501CF0CB40ECB50E32E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_EntityCurrentReportingStatus_296A80D5A4D0C501CF0CB40ECB50E32E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityFilerCategory" xlink:label="loc_dei_EntityFilerCategory_0E870BC2CECACEB27188B40ECB501CED" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_EntityFilerCategory_0E870BC2CECACEB27188B40ECB501CED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_754DDDE1B3BD58A33B09B40ECB50642F" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_754DDDE1B3BD58A33B09B40ECB50642F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentFiscalYearFocus" xlink:label="loc_dei_DocumentFiscalYearFocus_71F5E5A2C92E42842AC1B40ECB50AA4D" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_DocumentFiscalYearFocus_71F5E5A2C92E42842AC1B40ECB50AA4D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="loc_dei_DocumentFiscalPeriodFocus_E0C8963A98485F554279B40ECB503245" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_082E6FB0AE89A1217BB1B40ECB50599C" xlink:to="loc_dei_DocumentFiscalPeriodFocus_E0C8963A98485F554279B40ECB503245" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/FairValueMeasurement" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/FairValueMeasurementDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_BF4E28B9EE3C3494299E02524A33D0F1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1A4971680F04B226412C02524A32CE6F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_BF4E28B9EE3C3494299E02524A33D0F1" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1A4971680F04B226412C02524A32CE6F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_9808A281128F82029B1B02524A32A488" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1A4971680F04B226412C02524A32CE6F" xlink:to="loc_us-gaap_InvestmentTypeAxis_9808A281128F82029B1B02524A32A488" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_D3F222B2A85BD8D5048602524A32721A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_9808A281128F82029B1B02524A32A488" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_D3F222B2A85BD8D5048602524A32721A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_D3F222B2A85BD8D5048602524A32721A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_9808A281128F82029B1B02524A32A488" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_D3F222B2A85BD8D5048602524A32721A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableforsaleSecuritiesMember" xlink:label="loc_us-gaap_AvailableforsaleSecuritiesMember_47795A0E94222F2E141602524A322671" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_D3F222B2A85BD8D5048602524A32721A" xlink:to="loc_us-gaap_AvailableforsaleSecuritiesMember_47795A0E94222F2E141602524A322671" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0F1B30EE3570C6D4C1D202524A333A5B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_1A4971680F04B226412C02524A32CE6F" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0F1B30EE3570C6D4C1D202524A333A5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7485217D11A56E471C9902524A3352CF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0F1B30EE3570C6D4C1D202524A333A5B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7485217D11A56E471C9902524A3352CF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7485217D11A56E471C9902524A3352CF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0F1B30EE3570C6D4C1D202524A333A5B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7485217D11A56E471C9902524A3352CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_6DF9656B4E5C3D07F8F902524A33A244" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7485217D11A56E471C9902524A3352CF" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_6DF9656B4E5C3D07F8F902524A33A244" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_88372C732BE8434729A402524A33376C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7485217D11A56E471C9902524A3352CF" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_88372C732BE8434729A402524A33376C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_108AF93E4A9AB51D96F702524A3391B5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_BF4E28B9EE3C3494299E02524A33D0F1" xlink:to="loc_us-gaap_AvailableForSaleSecurities_108AF93E4A9AB51D96F702524A3391B5" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/FairValueMeasurementDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_DD0C30E782A63468CA470251FD6B3333" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5DCC817ED6141C0D37C80251FD6B50AA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_DD0C30E782A63468CA470251FD6B3333" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5DCC817ED6141C0D37C80251FD6B50AA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_EDBB33E3DEA6358BC79F0251FD6BC18C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5DCC817ED6141C0D37C80251FD6B50AA" xlink:to="loc_us-gaap_InvestmentTypeAxis_EDBB33E3DEA6358BC79F0251FD6BC18C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_D2D83D708EFDBB9EDF450251FD6BA153_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_EDBB33E3DEA6358BC79F0251FD6BC18C" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_D2D83D708EFDBB9EDF450251FD6BA153_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_D2D83D708EFDBB9EDF450251FD6BA153" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_EDBB33E3DEA6358BC79F0251FD6BC18C" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_D2D83D708EFDBB9EDF450251FD6BA153" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableforsaleSecuritiesMember" xlink:label="loc_us-gaap_AvailableforsaleSecuritiesMember_9AE853EE02C20C6D1A9E0251FD6B5F29" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_D2D83D708EFDBB9EDF450251FD6BA153" xlink:to="loc_us-gaap_AvailableforsaleSecuritiesMember_9AE853EE02C20C6D1A9E0251FD6B5F29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_47A43822BB1090BFE9610251FD6BC7B6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5DCC817ED6141C0D37C80251FD6B50AA" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_47A43822BB1090BFE9610251FD6BC7B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_FEBBB41F3654D0A5CCA80251FD6BCEDB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_47A43822BB1090BFE9610251FD6BC7B6" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_FEBBB41F3654D0A5CCA80251FD6BCEDB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_FEBBB41F3654D0A5CCA80251FD6BCEDB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_47A43822BB1090BFE9610251FD6BC7B6" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_FEBBB41F3654D0A5CCA80251FD6BCEDB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_78935AD9925DE78113200251FD6B7117" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_FEBBB41F3654D0A5CCA80251FD6BCEDB" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_78935AD9925DE78113200251FD6B7117" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BA18B146123F9D44CC2F0251FD6B7ECD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_5DCC817ED6141C0D37C80251FD6B50AA" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BA18B146123F9D44CC2F0251FD6B7ECD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_210511A0CA695AD47C380251FD6B68C5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BA18B146123F9D44CC2F0251FD6B7ECD" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_210511A0CA695AD47C380251FD6B68C5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_210511A0CA695AD47C380251FD6B68C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_BA18B146123F9D44CC2F0251FD6B7ECD" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_210511A0CA695AD47C380251FD6B68C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_4EE935BB9910BE9F77510251FD6B498D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_210511A0CA695AD47C380251FD6B68C5" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_4EE935BB9910BE9F77510251FD6B498D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_B3E2F87891E1D8763EA60251FD6BD86D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_210511A0CA695AD47C380251FD6B68C5" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_B3E2F87891E1D8763EA60251FD6BD86D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_90142C77EEBDBC90DDCA0251FD6B86FA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_210511A0CA695AD47C380251FD6B68C5" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_90142C77EEBDBC90DDCA0251FD6B86FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesCurrent_E2DB7E3C97E64912560D0252E8D15BE5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_DD0C30E782A63468CA470251FD6B3333" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesCurrent_E2DB7E3C97E64912560D0252E8D15BE5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesNoncurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent_4ACF929D8641B37710210251FFDE2369" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_DD0C30E782A63468CA470251FD6B3333" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent_4ACF929D8641B37710210251FFDE2369" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_BF5568B457FD71759CE6025363723D6E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_DD0C30E782A63468CA470251FD6B3333" xlink:to="loc_us-gaap_AvailableForSaleSecurities_BF5568B457FD71759CE6025363723D6E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/FairValueMeasurementDetails2" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D579A5D4F22F1DF0D9CAE982153105C5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2EA3B698F98F65EE8614E98215313ECF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D579A5D4F22F1DF0D9CAE982153105C5" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2EA3B698F98F65EE8614E98215313ECF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_59E7DCE64443BA0BC85FE982153184A8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2EA3B698F98F65EE8614E98215313ECF" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_59E7DCE64443BA0BC85FE982153184A8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_43D54E0E0FD1193C7337E9821531A04A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_59E7DCE64443BA0BC85FE982153184A8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_43D54E0E0FD1193C7337E9821531A04A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_43D54E0E0FD1193C7337E9821531A04A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_59E7DCE64443BA0BC85FE982153184A8" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_43D54E0E0FD1193C7337E9821531A04A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_57A4451B7CFC04E5C5E3E98215314E7B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2EA3B698F98F65EE8614E98215313ECF" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_57A4451B7CFC04E5C5E3E98215314E7B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D145A77A0B07821CCB28E9821531B3FE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_57A4451B7CFC04E5C5E3E98215314E7B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D145A77A0B07821CCB28E9821531B3FE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D145A77A0B07821CCB28E9821531B3FE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_57A4451B7CFC04E5C5E3E98215314E7B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D145A77A0B07821CCB28E9821531B3FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_77D5ACF488E7484019F1E982154564FA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D145A77A0B07821CCB28E9821531B3FE" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_77D5ACF488E7484019F1E982154564FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_B37395617C00FD2DE64AE982154DAAB4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D145A77A0B07821CCB28E9821531B3FE" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_B37395617C00FD2DE64AE982154DAAB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_4E0224B08C44A69BE0F2E9821555DA97" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_D145A77A0B07821CCB28E9821531B3FE" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_4E0224B08C44A69BE0F2E9821555DA97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure" xlink:label="loc_us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure_BAEB03F18DC3D7383DA4E982153AFE39" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_D579A5D4F22F1DF0D9CAE982153105C5" xlink:to="loc_us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure_BAEB03F18DC3D7383DA4E982153AFE39" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/FairValueMeasurementTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/GainOnSaleOfBuildingDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/GainOnSaleOfBuildingNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/GainOnSaleOfBuildingTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/IncomeTaxesEffectiveTaxRateDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/Inventories" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/InventoriesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/InventoriesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/InvestmentSecurities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/InvestmentSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_5FAEFF88430F49C9FAD902554764D0AD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_DD09E6372E3528BC9264025547630C41" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_5FAEFF88430F49C9FAD902554764D0AD" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_DD09E6372E3528BC9264025547630C41" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_151FFE47613E822BB18902554854A79E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_DD09E6372E3528BC9264025547630C41" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_151FFE47613E822BB18902554854A79E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB149D1D68917DAF6308025549252A62_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_151FFE47613E822BB18902554854A79E" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB149D1D68917DAF6308025549252A62_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB149D1D68917DAF6308025549252A62" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_151FFE47613E822BB18902554854A79E" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB149D1D68917DAF6308025549252A62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_B27FC7921263F63C937C025548A67204" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_EB149D1D68917DAF6308025549252A62" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_B27FC7921263F63C937C025548A67204" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_C41D5C220A10A9DD873E0255480EFDDE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_DD09E6372E3528BC9264025547630C41" xlink:to="loc_us-gaap_InvestmentTypeAxis_C41D5C220A10A9DD873E0255480EFDDE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_ED95ED5CD2C8D6FE9694025548DFA4D2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_C41D5C220A10A9DD873E0255480EFDDE" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_ED95ED5CD2C8D6FE9694025548DFA4D2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_ED95ED5CD2C8D6FE9694025548DFA4D2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_C41D5C220A10A9DD873E0255480EFDDE" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_ED95ED5CD2C8D6FE9694025548DFA4D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableforsaleSecuritiesMember" xlink:label="loc_us-gaap_AvailableforsaleSecuritiesMember_77859B3C1733766887C3025548ECAFB2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_ED95ED5CD2C8D6FE9694025548DFA4D2" xlink:to="loc_us-gaap_AvailableforsaleSecuritiesMember_77859B3C1733766887C3025548ECAFB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_E43F1AEA34C89BC6C3F1025547A2AF51" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_DD09E6372E3528BC9264025547630C41" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_E43F1AEA34C89BC6C3F1025547A2AF51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_380041AE90048FBE4CCA02554898D66C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_E43F1AEA34C89BC6C3F1025547A2AF51" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_380041AE90048FBE4CCA02554898D66C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_380041AE90048FBE4CCA02554898D66C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_E43F1AEA34C89BC6C3F1025547A2AF51" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_380041AE90048FBE4CCA02554898D66C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_13618FF84986579EBB0F025549343AF3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_380041AE90048FBE4CCA02554898D66C" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_13618FF84986579EBB0F025549343AF3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_083F1A2D9305F77237DE025547631F50" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_DD09E6372E3528BC9264025547630C41" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_083F1A2D9305F77237DE025547631F50" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_498207F448A08805300C02554764E08A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_083F1A2D9305F77237DE025547631F50" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_498207F448A08805300C02554764E08A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_498207F448A08805300C02554764E08A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_083F1A2D9305F77237DE025547631F50" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_498207F448A08805300C02554764E08A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_8ECE24F2378974E51FAC02554764D809" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_DD09E6372E3528BC9264025547630C41" xlink:to="loc_us-gaap_RangeAxis_8ECE24F2378974E51FAC02554764D809" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_EDC536626CAB5E94D473025547641595_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_8ECE24F2378974E51FAC02554764D809" xlink:to="loc_us-gaap_RangeMember_EDC536626CAB5E94D473025547641595_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_EDC536626CAB5E94D473025547641595" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_8ECE24F2378974E51FAC02554764D809" xlink:to="loc_us-gaap_RangeMember_EDC536626CAB5E94D473025547641595" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_187EFCC1F4DAFB7A695E02554793ED80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_5FAEFF88430F49C9FAD902554764D0AD" xlink:to="loc_us-gaap_AvailableForSaleSecurities_187EFCC1F4DAFB7A695E02554793ED80" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/InvestmentSecuritiesDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_C009CA113B6CF000E61CE917BB78AF11" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_3742AE7AC6D800784DDDE917BB78FD5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_C009CA113B6CF000E61CE917BB78AF11" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_3742AE7AC6D800784DDDE917BB78FD5C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_1BA1A32C7F8C9A706715E917BB78E878" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_3742AE7AC6D800784DDDE917BB78FD5C" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_1BA1A32C7F8C9A706715E917BB78E878" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_1BA1A32C7F8C9A706715E917BB78E878" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_1BA1A32C7F8C9A706715E917BB78E878" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NontaxableMunicipalNotesMember" xlink:label="loc_us-gaap_NontaxableMunicipalNotesMember_3B875011A13B34AE818FE917BB963D32" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191" xlink:to="loc_us-gaap_NontaxableMunicipalNotesMember_3B875011A13B34AE818FE917BB963D32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CorporateBondSecuritiesMember" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_2EB3BDE377643A370B03E917BBAA3C23" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_2EB3BDE377643A370B03E917BBAA3C23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_USTreasurySecuritiesMember" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_7474E90A2E14808A4CA6E917BBB4BB47" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_7474E90A2E14808A4CA6E917BBB4BB47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommercialPaperMember" xlink:label="loc_us-gaap_CommercialPaperMember_7E1068560DDC9F81333AE917BBBE2024" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191" xlink:to="loc_us-gaap_CommercialPaperMember_7E1068560DDC9F81333AE917BBBE2024" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CertificatesOfDepositMember" xlink:label="loc_us-gaap_CertificatesOfDepositMember_D95DF650121AE7D2F19DE917BBC8CAD4" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_4235D7629E1C243A5F8BE917BB78C191" xlink:to="loc_us-gaap_CertificatesOfDepositMember_D95DF650121AE7D2F19DE917BBC8CAD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_703DD377CA004581B237E917BB78FD86" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_3742AE7AC6D800784DDDE917BB78FD5C" xlink:to="loc_us-gaap_RangeAxis_703DD377CA004581B237E917BB78FD86" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_38499D4636E1130C4BBDE917BB782C60_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_703DD377CA004581B237E917BB78FD86" xlink:to="loc_us-gaap_RangeMember_38499D4636E1130C4BBDE917BB782C60_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_38499D4636E1130C4BBDE917BB782C60" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_703DD377CA004581B237E917BB78FD86" xlink:to="loc_us-gaap_RangeMember_38499D4636E1130C4BBDE917BB782C60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_35A3F93B1D6719F4A839E917BB829D93" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_C009CA113B6CF000E61CE917BB78AF11" xlink:to="loc_us-gaap_AvailableForSaleSecurities_35A3F93B1D6719F4A839E917BB829D93" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/InvestmentSecuritiesDetails2" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_06DF05D7F69D87D0BBD5E91BDF1B8EA8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_BB1B141BEEB34A077590E91AE00B5704" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_06DF05D7F69D87D0BBD5E91BDF1B8EA8" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_BB1B141BEEB34A077590E91AE00B5704" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_88AAA672B556336D4FF7E91AE00B4C64" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_BB1B141BEEB34A077590E91AE00B5704" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_88AAA672B556336D4FF7E91AE00B4C64" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_2786708987851DBA85AFE91AE00B9277_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_88AAA672B556336D4FF7E91AE00B4C64" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_2786708987851DBA85AFE91AE00B9277_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_2786708987851DBA85AFE91AE00B9277" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_88AAA672B556336D4FF7E91AE00B4C64" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_2786708987851DBA85AFE91AE00B9277" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_E4BF9E1354E2595F93ABE91AE015939F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_BB1B141BEEB34A077590E91AE00B5704" xlink:to="loc_us-gaap_RangeAxis_E4BF9E1354E2595F93ABE91AE015939F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_344C1E17CF002F0B5F1DE91AE0159BFA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_E4BF9E1354E2595F93ABE91AE015939F" xlink:to="loc_us-gaap_RangeMember_344C1E17CF002F0B5F1DE91AE0159BFA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_344C1E17CF002F0B5F1DE91AE0159BFA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_E4BF9E1354E2595F93ABE91AE015939F" xlink:to="loc_us-gaap_RangeMember_344C1E17CF002F0B5F1DE91AE0159BFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesCurrent_9F2204A1D86B9369631BE91BDF1E2683" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_06DF05D7F69D87D0BBD5E91BDF1B8EA8" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesCurrent_9F2204A1D86B9369631BE91BDF1E2683" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecuritiesNoncurrent" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent_E5D87FFFE4E4A4D6A823E91BDF1EE7DC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_06DF05D7F69D87D0BBD5E91BDF1B8EA8" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesNoncurrent_E5D87FFFE4E4A4D6A823E91BDF1EE7DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AvailableForSaleSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecurities_877977878858A94E6E01E91BDF1F081D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_06DF05D7F69D87D0BBD5E91BDF1B8EA8" xlink:to="loc_us-gaap_AvailableForSaleSecurities_877977878858A94E6E01E91BDF1F081D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/InvestmentSecuritiesTables" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_5D5F81A7B649E06C6809E91DE2D81F28" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesTable" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_7C7AE7B2FA5B59C08B8FE91DE2D59CA8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_5D5F81A7B649E06C6809E91DE2D81F28" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_7C7AE7B2FA5B59C08B8FE91DE2D59CA8" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_CFC9E496A17C49DBF972E91DE2D6EEEB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_7C7AE7B2FA5B59C08B8FE91DE2D59CA8" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_CFC9E496A17C49DBF972E91DE2D6EEEB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_1948560CC5C1CCDFB355E91DE2D6DD13_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_CFC9E496A17C49DBF972E91DE2D6EEEB" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_1948560CC5C1CCDFB355E91DE2D6DD13_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:label="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_1948560CC5C1CCDFB355E91DE2D6DD13" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_CFC9E496A17C49DBF972E91DE2D6EEEB" xlink:to="loc_us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_1948560CC5C1CCDFB355E91DE2D6DD13" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_56D497CC8EE607FEB114E91DE2D7B192" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesTable_7C7AE7B2FA5B59C08B8FE91DE2D59CA8" xlink:to="loc_us-gaap_RangeAxis_56D497CC8EE607FEB114E91DE2D7B192" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_D36E6673A30B8524CBF4E91DE2D714B6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_56D497CC8EE607FEB114E91DE2D7B192" xlink:to="loc_us-gaap_RangeMember_D36E6673A30B8524CBF4E91DE2D714B6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_D36E6673A30B8524CBF4E91DE2D714B6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_56D497CC8EE607FEB114E91DE2D7B192" xlink:to="loc_us-gaap_RangeMember_D36E6673A30B8524CBF4E91DE2D714B6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/LegalSettlement" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/LegalSettlementLegalSettlementChargeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/MajorCustomer" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/MajorCustomerDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_28E2F9261D35FA144987B40ECBEC492D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="loc_us-gaap_ConcentrationRiskTable_D8352BFC41C6C2AE7551B40ECBEC0E11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_28E2F9261D35FA144987B40ECBEC492D" xlink:to="loc_us-gaap_ConcentrationRiskTable_D8352BFC41C6C2AE7551B40ECBEC0E11" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_E6F87CDD951C68338981B40ECBEC5D33" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_D8352BFC41C6C2AE7551B40ECBEC0E11" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_E6F87CDD951C68338981B40ECBEC5D33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_40E071742CB44F76F98AB40ECBECD491_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_E6F87CDD951C68338981B40ECBEC5D33" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_40E071742CB44F76F98AB40ECBECD491_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_40E071742CB44F76F98AB40ECBECD491" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_E6F87CDD951C68338981B40ECBEC5D33" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_40E071742CB44F76F98AB40ECBECD491" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember_CF546C270544D637DEB2B40ECBEC4F87" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_40E071742CB44F76F98AB40ECBECD491" xlink:to="loc_us-gaap_AccountsReceivableMember_CF546C270544D637DEB2B40ECBEC4F87" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaap_SalesRevenueNetMember_830379C2A92239354F64B40ECBECF570" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_40E071742CB44F76F98AB40ECBECD491" xlink:to="loc_us-gaap_SalesRevenueNetMember_830379C2A92239354F64B40ECBECF570" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MajorCustomersAxis" xlink:label="loc_us-gaap_MajorCustomersAxis_2892D06104EDB6138077B40ECBECF58F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_D8352BFC41C6C2AE7551B40ECBEC0E11" xlink:to="loc_us-gaap_MajorCustomersAxis_2892D06104EDB6138077B40ECBECF58F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_AC034D888A9F207AA41EB40ECBEC6ED9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MajorCustomersAxis_2892D06104EDB6138077B40ECBECF58F" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_AC034D888A9F207AA41EB40ECBEC6ED9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NameOfMajorCustomerDomain" xlink:label="loc_us-gaap_NameOfMajorCustomerDomain_AC034D888A9F207AA41EB40ECBEC6ED9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MajorCustomersAxis_2892D06104EDB6138077B40ECBECF58F" xlink:to="loc_us-gaap_NameOfMajorCustomerDomain_AC034D888A9F207AA41EB40ECBEC6ED9" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_HospiraMember" xlink:label="loc_icui_HospiraMember_3492917D509563F477D8B40ECBEC72CA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NameOfMajorCustomerDomain_AC034D888A9F207AA41EB40ECBEC6ED9" xlink:to="loc_icui_HospiraMember_3492917D509563F477D8B40ECBEC72CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_8BC76945C0F71D18B759B40ECBEC7FAA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_28E2F9261D35FA144987B40ECBEC492D" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_8BC76945C0F71D18B759B40ECBEC7FAA" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_EntityWideAccountsReceivableMajorCustomerPercent" xlink:label="loc_icui_EntityWideAccountsReceivableMajorCustomerPercent_A03BA44771756D552ADAB40ECBECD99D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_28E2F9261D35FA144987B40ECBEC492D" xlink:to="loc_icui_EntityWideAccountsReceivableMajorCustomerPercent_A03BA44771756D552ADAB40ECBECD99D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/NetIncomePerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/NetIncomePerShareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_C7204F8A802E8FAE1E4AE98F6EF1D549" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_C7204F8A802E8FAE1E4AE98F6EF1D549" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_EEC3AA29B259B156B363E98F6EF266CE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_C7204F8A802E8FAE1E4AE98F6EF1D549" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_EEC3AA29B259B156B363E98F6EF266CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_585C565E8E995EED7E19E98F6EF25987_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_EEC3AA29B259B156B363E98F6EF266CE" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_585C565E8E995EED7E19E98F6EF25987_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_585C565E8E995EED7E19E98F6EF25987" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_EEC3AA29B259B156B363E98F6EF266CE" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_585C565E8E995EED7E19E98F6EF25987" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaap_ProfitLoss_0ECC55345D8AA99CBCD5E98F6EF350E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:to="loc_us-gaap_ProfitLoss_0ECC55345D8AA99CBCD5E98F6EF350E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_9EC1E98B28DA5AAC1292E98F6EF34997" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_9EC1E98B28DA5AAC1292E98F6EF34997" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_80E468BD7830FC6C3104E98F6EF316C7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_80E468BD7830FC6C3104E98F6EF316C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_A2BB0D74B4B704F6A5B3E98F6EF3BB20" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_A2BB0D74B4B704F6A5B3E98F6EF3BB20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_87FCD0721E02579B11C6E98F6EF319EF" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:to="loc_us-gaap_EarningsPerShareBasic_87FCD0721E02579B11C6E98F6EF319EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_8ABB2C9DAE75A2089A70E98F6EF46E10" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_42E8B2A978ABAA1BAE74E98F6EF2FD5D" xlink:to="loc_us-gaap_EarningsPerShareDiluted_8ABB2C9DAE75A2089A70E98F6EF46E10" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/NetIncomePerShareDetails1" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/NetIncomePerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/NewAccountingPronouncements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/NewAccountingPronouncementsNewAccountingPronouncementsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/PropertyAndEquipment" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/PropertyAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_36764AB64FFE4AA6B3E4E48A12D3B3D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_36764AB64FFE4AA6B3E4E48A12D3B3D6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ABE5FB772A1E4919EF2E48A12D3C666" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_36764AB64FFE4AA6B3E4E48A12D3B3D6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ABE5FB772A1E4919EF2E48A12D3C666" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_117B02176C257F8A7A0DE48A12D3E118_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ABE5FB772A1E4919EF2E48A12D3C666" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_117B02176C257F8A7A0DE48A12D3E118_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_117B02176C257F8A7A0DE48A12D3E118" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_2ABE5FB772A1E4919EF2E48A12D3C666" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_117B02176C257F8A7A0DE48A12D3E118" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LandBuildingsAndImprovementsMember" xlink:label="loc_us-gaap_LandBuildingsAndImprovementsMember_258FC4149A46926F4A92E48A12D352AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_117B02176C257F8A7A0DE48A12D3E118" xlink:to="loc_us-gaap_LandBuildingsAndImprovementsMember_258FC4149A46926F4A92E48A12D352AB" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_MoldsMember" xlink:label="loc_icui_MoldsMember_CE2693C641B1B2329CF6E48A12D3A1DB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_117B02176C257F8A7A0DE48A12D3E118" xlink:to="loc_icui_MoldsMember_CE2693C641B1B2329CF6E48A12D3A1DB" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_ComputerEquipmentAndSoftwareMember" xlink:label="loc_icui_ComputerEquipmentAndSoftwareMember_BB06808F4FB7465D9628E48A12D37B57" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_117B02176C257F8A7A0DE48A12D3E118" xlink:to="loc_icui_ComputerEquipmentAndSoftwareMember_BB06808F4FB7465D9628E48A12D37B57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_34B9705C16CB674BCB97E48A12D377B5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_34B9705C16CB674BCB97E48A12D377B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_3831D470992E1989AFB3E48A12D3FE9D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_3831D470992E1989AFB3E48A12D3FE9D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_176D28BA1C4CC5A47EE7E48A12D3D284" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_176D28BA1C4CC5A47EE7E48A12D3D284" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MachineryAndEquipmentGross" xlink:label="loc_us-gaap_MachineryAndEquipmentGross_B993BBF0D54917CFF83BE48A12D31A25" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:to="loc_us-gaap_MachineryAndEquipmentGross_B993BBF0D54917CFF83BE48A12D31A25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FurnitureAndFixturesGross" xlink:label="loc_us-gaap_FurnitureAndFixturesGross_3078053C16E25DA24E56E48A12D38E82" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:to="loc_us-gaap_FurnitureAndFixturesGross_3078053C16E25DA24E56E48A12D38E82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConstructionInProgressGross" xlink:label="loc_us-gaap_ConstructionInProgressGross_6F7DCFB92D62B6378EB8E48A12D3135C" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_818B5C0BADA70B01088DE48A12D3699D" xlink:to="loc_us-gaap_ConstructionInProgressGross_6F7DCFB92D62B6378EB8E48A12D3135C" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/PropertyAndEquipmentTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/RestructuringChargesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/RestructuringChargesDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_310BD5399E47667FC7CFE951DFEC7CA6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_310BD5399E47667FC7CFE951DFEC7CA6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_95C176B989A823AB18BFE951DFECFF73" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_310BD5399E47667FC7CFE951DFEC7CA6" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_95C176B989A823AB18BFE951DFECFF73" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_95C176B989A823AB18BFE951DFECFF73" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_95C176B989A823AB18BFE951DFECFF73" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_2A5D98679340DCF745B8E951DFECC183" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7" xlink:to="loc_us-gaap_EmployeeSeveranceMember_2A5D98679340DCF745B8E951DFECC183" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_GovernmentincentiverepaymentMember" xlink:label="loc_icui_GovernmentincentiverepaymentMember_382AA86ECA64455E333CE951DFEC5FD1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7" xlink:to="loc_icui_GovernmentincentiverepaymentMember_382AA86ECA64455E333CE951DFEC5FD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SpecialTerminationBenefitsMember" xlink:label="loc_us-gaap_SpecialTerminationBenefitsMember_0C0B5A1E72AF2827FFEAE951DFECF431" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7" xlink:to="loc_us-gaap_SpecialTerminationBenefitsMember_0C0B5A1E72AF2827FFEAE951DFECF431" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherRestructuringMember" xlink:label="loc_us-gaap_OtherRestructuringMember_218BC9EBD9FF69023B6EE951DFECB5E4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7" xlink:to="loc_us-gaap_OtherRestructuringMember_218BC9EBD9FF69023B6EE951DFECB5E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FacilityClosingMember" xlink:label="loc_us-gaap_FacilityClosingMember_18FC7D7E2CA2DB9B7481E951DFEC023D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_520AF45E028E27086750E951DFECFED7" xlink:to="loc_us-gaap_FacilityClosingMember_18FC7D7E2CA2DB9B7481E951DFEC023D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringReserveRollForward" xlink:label="loc_us-gaap_RestructuringReserveRollForward_FDFF391BAD72947F0446E951DFEC4D4A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:to="loc_us-gaap_RestructuringReserveRollForward_FDFF391BAD72947F0446E951DFEC4D4A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_74A352DAE92B01E8BF34E951DFEC3609" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:to="loc_us-gaap_RestructuringReserve_74A352DAE92B01E8BF34E951DFEC3609" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_A6E1C2BD881F3EB2B9F2E951DFEC485A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:to="loc_us-gaap_RestructuringCharges_A6E1C2BD881F3EB2B9F2E951DFEC485A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsForRestructuring" xlink:label="loc_us-gaap_PaymentsForRestructuring_0627DA457188086404E2E951DFEC8FB6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:to="loc_us-gaap_PaymentsForRestructuring_0627DA457188086404E2E951DFEC8FB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringReserveTranslationAdjustment" xlink:label="loc_us-gaap_RestructuringReserveTranslationAdjustment_878C7098E366FFBEAA08E951DFECAAA3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:to="loc_us-gaap_RestructuringReserveTranslationAdjustment_878C7098E366FFBEAA08E951DFECAAA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestructuringReserveAccrualAdjustment1" xlink:label="loc_us-gaap_RestructuringReserveAccrualAdjustment1_953B2B090CBEBCE81950E951DFECE98A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_2AEA0B995E462BF713EBE951DFEC9406" xlink:to="loc_us-gaap_RestructuringReserveAccrualAdjustment1_953B2B090CBEBCE81950E951DFECE98A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/RestructuringChargesNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/RestructuringChargesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_C79F02730EBE34428A36025A3A5BA487" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaap_SubsequentEventTable_3B5020A252EB8AFD2013025A3A5B4BD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_C79F02730EBE34428A36025A3A5BA487" xlink:to="loc_us-gaap_SubsequentEventTable_3B5020A252EB8AFD2013025A3A5B4BD4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_CC630420BAAA18C0942C025A3A5B37C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_3B5020A252EB8AFD2013025A3A5B4BD4" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_CC630420BAAA18C0942C025A3A5B37C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_1509EEE9E34EF8CC8F9D025A3A5BCD38_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_CC630420BAAA18C0942C025A3A5B37C2" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_1509EEE9E34EF8CC8F9D025A3A5BCD38_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_1509EEE9E34EF8CC8F9D025A3A5BCD38" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_CC630420BAAA18C0942C025A3A5B37C2" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_1509EEE9E34EF8CC8F9D025A3A5BCD38" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_7EB7CD0EC8427A307DB1025A3A6A6AD7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_1509EEE9E34EF8CC8F9D025A3A5BCD38" xlink:to="loc_us-gaap_SubsequentEventMember_7EB7CD0EC8427A307DB1025A3A6A6AD7" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_SeniorSecuredCreditFacility" xlink:label="loc_icui_SeniorSecuredCreditFacility_791270C0057FA8F2E53A025A3E11BAF3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_C79F02730EBE34428A36025A3A5BA487" xlink:to="loc_icui_SeniorSecuredCreditFacility_791270C0057FA8F2E53A025A3E11BAF3" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_TermLoan" xlink:label="loc_icui_TermLoan_E863D10F2B02E79AAB0F025A3E30599D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_C79F02730EBE34428A36025A3A5BA487" xlink:to="loc_icui_TermLoan_E863D10F2B02E79AAB0F025A3E30599D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8EA402580A6D2A55E8E2025A3DF1B0A4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_C79F02730EBE34428A36025A3A5BA487" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8EA402580A6D2A55E8E2025A3DF1B0A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_CB687033FD8F76FB6835025A3A5BED8D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_C79F02730EBE34428A36025A3A5BA487" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_CB687033FD8F76FB6835025A3A5BED8D" xlink:type="arc" />
    <link:loc xlink:href="icui-20160930.xsd#icui_Numberofsharesissuedasconsideration" xlink:label="loc_icui_Numberofsharesissuedasconsideration_F887C7C7D0326FA6C311025A616D902B" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_C79F02730EBE34428A36025A3A5BA487" xlink:to="loc_icui_Numberofsharesissuedasconsideration_F887C7C7D0326FA6C311025A616D902B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.icumed.com/role/SubsequentEventsNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/SubsequentEventsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/TreasuryStock" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/TreasuryStockDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.icumed.com/role/TreasuryStockTables" xlink:type="extended" />
</link:linkbase>