SECURITIES AND EXCHANGE COMMISSION
                           WASHINGTON, D.C. 20549


                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                                (Amendment No.   )

                                ICU Medical, Inc.
                                (Name of Issuer)
                                   
                                  Common Stock
                         (Title of class of securities)

                                    44930G107
                                 (CUSIP number)


Check the following box if a fee is  being paid with this statement [x].


- ----------
*The  remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).



CUSIP No. 44930G107                   13G                    Page 2  of 8  Pages



- --------------------------------------------------------------------------------
   1.  NAME OF REPORTING PERSON(S)
       S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON(S)

          Morgan Stanley Dean Witter & Co.
          IRS  #  39-314-5972
  
- --------------------------------------------------------------------------------
   2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                             (a)  [  ]
                                                             (b)  [  ]


- --------------------------------------------------------------------------------
   3.  SEC USE ONLY




- --------------------------------------------------------------------------------
   4.  CITIZENSHIP OR PLACE OF ORGANIZATION

          The state of organization is Delaware.


- --------------------------------------------------------------------------------
   NUMBER OF      5.   SOLE VOTING POWER
     SHARES            0 
  BENEFICIALLY    --------------------------------------------------------------
    OWNED BY      6.   SHARED VOTING POWER
      EACH             455,700
   REPORTING      --------------------------------------------------------------
     PERSON       7.   SOLE DISPOSITIVE POWER
      WITH             0
                  --------------------------------------------------------------
                  8.   SHARED DISPOSITIVE POWER
                       455,700   
- --------------------------------------------------------------------------------
   9.  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     
          455,700

- --------------------------------------------------------------------------------
  10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*



- --------------------------------------------------------------------------------
  11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

          5.66%

- --------------------------------------------------------------------------------
  12.  TYPE OF REPORTING PERSON*

          IA, CO


- --------------------------------------------------------------------------------
                     *SEE INSTRUCTIONS BEFORE FILLING OUT!


CUSIP No. 44930G107                   13G                    Page 3  of 8  Pages



- --------------------------------------------------------------------------------
   1.  NAME OF REPORTING PERSON(S)
       S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON(S)

          Morgan Stanley & Co. Incorporated
          IRS # 13-265-5996
  
- --------------------------------------------------------------------------------
   2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                             (a)  [  ]
                                                             (b)  [  ]


- --------------------------------------------------------------------------------
   3.  SEC USE ONLY




- --------------------------------------------------------------------------------
   4.  CITIZENSHIP OR PLACE OF ORGANIZATION

          The state of organization is Delaware.


- --------------------------------------------------------------------------------
   NUMBER OF      5.   SOLE VOTING POWER
     SHARES              0 
  BENEFICIALLY    --------------------------------------------------------------
    OWNED BY      6.   SHARED VOTING POWER
      EACH               455,700
   REPORTING      --------------------------------------------------------------
     PERSON       7.   SOLE DISPOSITIVE POWER
      WITH               0
                  --------------------------------------------------------------
                  8.   SHARED DISPOSITIVE POWER
                         455,700
- --------------------------------------------------------------------------------
   9.  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

          455,700

- --------------------------------------------------------------------------------
  10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*



- --------------------------------------------------------------------------------
  11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

          5.66%

- --------------------------------------------------------------------------------
  12.  TYPE OF REPORTING PERSON*

          BD, CO
                         
- --------------------------------------------------------------------------------
                     *SEE INSTRUCTIONS BEFORE FILLING OUT!


                                       
CUSIP No. 44930G107                   13G                   Page 4  of  8  Pages





Item 1.     (a)   Name of Issuer:
                  ICU Medical, Inc.
                  --------------------------------------------------------------
            (b)   Address of Issuer's Principal Executive Offices:
                  951 Calle Amanecer
                  San Clemente, CA 92673                      
                  --------------------------------------------------------------
Item 2.     (a)   Name of Person Filing:
                           (a) Morgan Stanley Dean Witter & Co.
                           (b) Morgan Stanley & Co. Incorporated
                  --------------------------------------------------------------
            (b)   Address of Principal Business Office, or if None, Residence:
                           (a) 1585 Broadway
                               New  York, New  York  10036

                           (b) 1585 Broadway
                               New  York, New  York  10036
                  --------------------------------------------------------------
            (c)   Citizenship:
                           Incorporated  by  reference  to  Item  4  of  the
                           cover page  pertaining  to  each  reporting  person.

                               -------------------------------------------------
            (d)   Title of Class of Securities:
                           Common Stock
                  --------------------------------------------------------------
            (e)   CUSIP Number:
                           44930G107
                               -------------------------------------------------

Item 3.     (a)   Morgan Stanley Dean Witter & Co. is (e) an Investment Adviser 
                  registered under Section 203 of the Investment Advisers Act 
                  of 1940.

            (b)   Morgan Stanley & Co. Incorporated  is (a) a  Broker
                  Dealer registered  under  section  15 of  the Securities
                  Exchange Act of 1934.

 
                                      
CUSIP No. 44930G107                  13-G                   Page 5  of  8  Pages



Item 4.     Ownership.

               Incorporated  by  reference  to  Items  (5) - (9) and (11) of the
               cover page.

Item 5.     Ownership of Five Percent or Less of a Class.

               Inapplicable

Item 6.     Ownership of More Than Five Percent on Behalf of Another Person.

               Accounts managed on a discretionary basis by Morgan Stanley & Co.
               Incorporated,  a wholly owned  subsidiary of Morgan  Stanley Dean
               Witter & Co., are known to have the right to receive or the power
               to direct the receipt of dividends  from,  or the proceeds  from,
               the sale of such  securities.  No such account  holds more than 5
               percent of the class.

Item 7.     Identification and Classification of the Subsidiary which Acquired
            the Security Being Reported on By the Parent Holding Company.


Item 8.     Identification and Classification of Members of the Group.


Item 9.     Notice of Dissolution of Group.


Item 10.    Certification.

               By signing  below I certify that, to the best of my knowledge and
               belief,  the  securities  referred to above were  acquired in the
               ordinary course of business and were not acquired for the purpose
               of and do not have the  effect of  changing  or  influencing  the
               control of the issuer of such securities and were not acquired in
               connection  with or as a participant  in any  transaction  having
               such purpose or effect.


CUSIP No. 44930G107                   13-G                   Page 6  of  8 Pages


                                  Signature.


            After  reasonable  inquiry  and to the best of my  knowledge  and
            belief,  I  certify  that  the  information  set  forth  in  this
            statement is true, complete and correct.


Date:       February 2, 1999


Signature:  /s/ Bruce Bromberg
            -----------------------------------------------------------------
          
Name/Title  Bruce Bromberg / Vice President Morgan Stanley & Co. Incorporated
            -----------------------------------------------------------------
            MORGAN STANLEY DEAN WITTER & CO.

Date:       February 2, 1999


Signature:  /s/ Bruce Bromberg
            -----------------------------------------------------------------
          
Name/Title  Bruce Bromberg / Vice President Morgan Stanley & Co. Incorporated
            -----------------------------------------------------------------
            MORGAN STANLEY & CO. INCORPORATED


                       INDEX TO EXHIBITS                           PAGE
                       -----------------                           ----

EXHIBIT 1       Agreement to Make a Joint Filing                      7

EXHIBIT 2       Secretary's Certificate Authorizing Bruce Bromberg    8
                to Sign on behalf of Morgan Stanley Dean Witter & Co.
                         


* Attention. Intentional misstatements or omissions of fact constitute federal
  criminal violations (see 18 U.S.C. 1001).

(022597DTI)


 CUSIP No. 44930G107                  13-G                   Page 7  of  8 Pages


                            EXHIBIT 1 TO SCHEDULE 13G
               ---------------------------------------------------


                                FEBRUARY 2, 1999
               ---------------------------------------------------


               MORGAN STANLEY DEAN WITTER & CO. and MORGAN STANLEY & CO.

               INCORPORATED hereby agree that, unless  differentiated,  this

               Schedule 13G is filed on behalf of each of the parties.


            MORGAN STANLEY DEAN WITTER & CO.

            BY: /s/ Bruce Bromberg
            --------------------------------------------------------------------
            Bruce Bromberg / Vice President Morgan Stanley & Co. Incorporated

            MORGAN STANLEY & CO. INCORPORATED

            BY: /s/ Bruce Bromberg
            --------------------------------------------------------------------
            Bruce Bromberg / Vice President Morgan Stanley & Co. Incorporated

* Attention. Intentional misstatements or omissions of fact constitute federal
  criminal violations (see 18 U.S.C. 1001).





                                                              Page 8 of 8  Pages
                                  EXHIBIT 2                   ------------------

                 MORGAN STANLEY, DEAN WITTER, DISCOVER & CO.
                                      
                           SECRETARY'S CERTIFICATE
                                      



        I, Charlene R. Herzer, a duly elected and acting Assistant Secretary of
Morgan Stanley, Dean Witter, Discover & Co., a corporation organized and
existing under the laws of the State of Delaware (the "Corporation"), certify
that as approved by a Unanimous Consent of Directors in Lieu of a Meeting dated
as of May 31, 1997, the following persons are each authorized to sign reports
to be filed under Sections 13 and 16 of the Securities Exchange Act of 1934 on
behalf of the Corporation, and such authorizations are in full force and
effect as of this date:

                             Stuart J.M. Breslow
                             Robert G. Koppenol
                             Bruce Bromberg
                             Robin Sherak

        IN WITNESS WHEREOF, I have hereunto set my name and affixed the seal of
the Corporation as of the 3rd day of June, 1997.


                                          /s/ Charlene R. Herzer
                                         ------------------------
                                             Charlene R. Herzer
                                             Assistant Secretaty