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                                                                     Exhibit 5.1

                               Winston & Stawn LLP
                              35 West Wacker Drive
                             Chicago, Illinois 60601


                                  April 6, 2004


Medex, Inc.
MedVest Holdings Corporation
Medex Medical, Inc.
Medex Cardio-Pulmonary, Inc.
2231 Rutherford Road
Carlsbad, California 92008

     RE:  REGISTRATION STATEMENT ON FORM S-4 OF MEDEX, INC.
           AND THE GUARANTORS (AS DEFINED BELOW)

Ladies and Gentlemen:

     We have acted as special counsel to Medex, Inc., an Ohio corporation
(the "Company"), MedVest Holdings Corporation, an Ohio corporation
("Parent"), and certain of the Company's subsidiaries (together with Parent,
the "Guarantors") in connection with the preparation of the Registration
Statement on Form S-4 (the "Registration Statement") filed with the
Securities and Exchange Commission (the "Commission") on behalf of the
Company and the Guarantors, relating to the Company's offer to exchange $200
million aggregate principal amount of the Company's 8 7/8% Senior
Subordinated Notes due 2013 (the "New Notes") and the issuance of Guarantees
(as hereinafter defined) thereof by the Guarantors, which are to be offered
in exchange for an equivalent principal amount of the Company's currently
outstanding 8 7/8% Senior Subordinated Notes due 2013 (the "Old Notes"), all
as more fully described in the Registration Statement. The New Notes will be
issued under the Company's Indenture, dated as of May 21, 2003 (the
"Indenture"), between the Company, Guarantors and The Bank of New York, as
trustee (the "Trustee"). Capitalized terms used herein and not otherwise
defined shall have the meanings assigned to such terms in the prospectus (the
"Prospectus") contained in the Registration Statement.

     This opinion letter is delivered in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act of 1933, as amended
(the "Securities Act").

     In connection with this opinion, we have examined and are familiar with
originals or copies, certified or otherwise identified to our satisfaction, of
(i) the Registration Statement, in the form filed with the Commission and as
amended through the date hereof; (ii) the Certificate of Incorporation of the
Company and each of the Guarantors, as currently in effect; (iii) the Code of
Regulations of the Company and each of the Guarantors, as currently in effect;
(iv) the Indenture; (v) the form of the New Notes; and (vi) resolutions of the
Boards of Directors of the Company and each of the Guarantors, relating to,
among other things, the issuance and exchange

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Medex, Inc.
March 19, 2004
Page 2

of the New Notes for the Old Notes, the issuance of the Guarantees and the
filing of the Registration Statement. We also have examined such other documents
as we have deemed necessary or appropriate as a basis for the opinions set forth
below.

     In our examination, we have assumed the legal capacity of all natural
persons, the genuineness of all signatures, the authenticity of all documents
submitted to us as originals, the conformity to original documents of all
documents submitted to us as certified or photostatic copies, and the
authenticity of the originals of such latter documents. As to certain facts
material to this opinion, we have relied without independent verification upon
oral or written statements and representations of officers and other
representatives of the Company and others.

     Based upon and subject to the foregoing, we are of the opinion that:

     1.   When (i) the Registration Statement, as finally amended (including all
necessary post-effective amendments), shall have become effective under the
Securities Act, (ii) the New Notes are duly executed and authenticated in
accordance with the provisions of the Indenture, (iii) the issuance and exchange
of the New Notes for the Old Notes and the issuance of the Guarantees have been
duly authorized by requisite corporate action on the part of the Company and
each Guarantor, respectively, and (iv) the New Notes shall have been issued and
delivered in exchange for the Old Notes pursuant to the terms set forth in the
Prospectus, the New Notes and the Guarantees will be valid and binding
obligations of the Company and the Guarantors, respectively, entitled to the
benefits of the Indenture and enforceable against the Company and the
Guarantors, respectively, in accordance with their terms, except to the extent
that the enforceability thereof may be limited by (x) bankruptcy, insolvency,
fraudulent conveyance, reorganization, moratorium or other similar laws now or
hereafter in effect relating to creditors' rights generally and (y) general
principles of equity (regardless of whether enforceability is considered in a
proceeding at law or in equity).

     The foregoing opinions are limited to the laws of the United States and the
State of New York. We express no opinion as to the application of the securities
or blue sky laws of the various states to the issuance or exchange of the New
Notes.

     We hereby consent to the reference to our firm under the headings "Legal
Matters" in the Prospectus and to the filing of this opinion with the Commission
as an exhibit to the Registration Statement. In giving such consent, we do not
concede that we are experts within the meaning of the Securities Act or the
rules and regulations thereunder or that this consent is required by Section 7
of the Securities Act.

                                   Very truly yours,


                                   WINSTON & STRAWN LLP