Document:

<PAGE>

                                                                   Exhibit 10.16

                         SUPPLEMENT NO. 1 dated as of May ___, 2002, to the
                    PLEDGE AGREEMENT dated as of April 7,1998, among HUDSON
                    RESPIRATORY CARE INC., a California corporation (the
                    "Borrower"), RIVER HOLDINGS CORP., a Delaware corporation
                    ("Holding") and each subsidiary of the Borrower listed on
                    Schedule I hereto (each such subsidiary individually a
                    "Subsidiary Pledgor" and collectively, the "Subsidiary
                    Pledgors"; the Borrower, Holding and Subsidiary Pledgors are
                    referred to collectively herein as the "Pledgors") and
                    BANKERS TRUST COMPANY, a New York banking corporation
                    ("BTCo.% as collateral agent (in such capacity, the
                    "Collateral Agent") for the Secured Parties (as defined in
                    the Credit Agreement referred to below)

     A. Reference is made to (a) the Credit Agreement dated as of April 7, 1998
(as amended, supplemented or otherwise modified from time to time, the "Credit
Agreement"), among the Borrower, Holding, the lenders from time to time party
thereto (the "Lenders"), BTCo., as administrative agent for the Lenders,
Collateral Agent, swingline lender and as issuing bank (in such capacity, the
"Issuing Bank") and (b) the Holding Guarantee Agreement dated as of April 7,
1998 (as amended, supplemented or otherwise modified from time to time, the
"Holding Guarantee Agreement"), between Holding and the Collateral Agent.

     B. Capitalized terms used herein and not otherwise defined herein shall
have the meanings assigned to such terms in the Credit Agreement.

     C. The Pledgors have entered into the Pledge Agreement in order to induce
the Lenders to make Loans and the Issuing Bank to issue Letters of Credit.
Pursuant to Section 5.11 of the Credit Agreement, each Domestic Subsidiary of
the Borrower that was not in existence or not a Subsidiary on the date of the
Credit Agreement is required to enter into the Pledge Agreement as a Subsidiary
Pledgor upon becoming a Subsidiary if such Subsidiary owns or possesses property
of a type that would be considered Collateral under the Pledge Agreement.
Section 24 of the Pledge Agreement provides that such Subsidiaries may become
Subsidiary Pledgors under the Pledge Agreement by execution and delivery of an
instrument in the form of this Supplement. The undersigned Subsidiary (the "New
Pledgor") is executing this Supplement in accordance with the requirements of
the Credit Agreement to become a Subsidiary Pledgor under the Pledge Agreement
in order to induce the Lenders to make additional Loans and the Issuing Bank to
issue additional Letters of Credit and as consideration for Loans previously
made and Letters of Credit previously issued.

     Accordingly, the Collateral Agent and the New Pledgor agree as follows:

     SECTION 1. In accordance with Section 24 of the Pledge Agreement, the New
Pledgor by its signature below becomes a Pledgor under the Pledge Agreement with
the same force and effect as if originally named therein as a Pledgor and the
New Pledgor hereby agrees (a) to all the terms and provisions of the Pledge
Agreement applicable to it as a Pledgor thereunder and (b) represents and
warrants that the representations and warranties made by it as a Pledgor
thereunder are true and correct on and as of the date hereof. In furtherance of
the foregoing, the New Pledgor, as security for the payment and performance in
full of the Obligations (as defined

<PAGE>

                                                                   Exhibit 10.16
                                                                               2

in the Pledge Agreement), does hereby create and grant to the Collateral Agent,
its successors and assigns, for the benefit of the Secured Parties, their
successors and assigns, a security interest in and lien on all of the New
Pledgor's right, title and interest in and to the Collateral (as defined in the
Pledge Agreement, except the Collateral as it relates to the New Pledgor shall
not include the New Pledgor's interest in the one share of Industrias Hudson
held by the New Pledgor) of the New Pledgor. Each reference to a "Subsidiary
Pledgor" or a "Pledgor" in the Pledge Agreement shall be deemed to include the
New Pledgor. The Pledge Agreement is hereby incorporated herein by reference.

     SECTION 2. This Supplement may be executed in counterparts, each of which
shall constitute an original, but all of which when taken together shall
constitute a single contract. This Supplement shall become effective when the
Collateral Agent shall have received counterparts of this Supplement that, when
taken together, bear the signatures of the New Pledgor and the Collateral Agent.
Delivery of an executed signature page to this Supplement by facsimile
transmission shall be as effective as delivery of a manually signed counterpart
of this Supplement.

     SECTION 3. The New Pledgor hereby represents and warrants that set forth on
Schedule I attached hereto is a true and correct schedule of all its Pledged
Securities.

     SECTION 4. Except as expressly supplemented hereby, the Pledge Agreement
shall remain in full force and effect.

     Section 5. THIS SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD FOR PRINCIPLES
OF CONFLICTS OF LAWS.

     SECTION 6. In case any one or more of the provisions contained in this
Supplement should be held invalid, illegal or unenforceable in any respect,
neither party hereto shall be required to comply with such provision for so long
as such provision is held to be invalid, illegal or unenforceable, but the
validity, legality and enforceability of the remaining provisions contained
herein and in the Pledge Agreement shall not in any way be affected or impaired.
The parties hereto shall endeavor in good-faith negotiations to replace the
invalid, illegal or unenforceable provisions with valid provisions the economic
effect of which comes as close as possible to that of the invalid, illegal or
unenforceable provisions.

     SECTION 7. All communication and notices hereunder shall be in writing and
given as provided in Section 15 of the Pledge Agreement. All communications and
notices hereunder to the New Pledgor shall be given to it in care of the
Borrower.

     SECTION 8. The New Pledgor agrees to reimburse the Collateral Agent for its
reasonable out-of-pocket expenses in connection with this Supplement, including
the reasonable fees, other charges and disbursements of counsel for the
Collateral Agent.

<PAGE>

                                                                   Exhibit 10.16
                                                                               3

     IN WITNESS WHEREOF, the New Pledgor and the Collateral Agent have duly
executed this Supplement to the Pledge Agreement as of the day and year first
above written.

                                    IH HOLDING LLC,

                                    By:  HUDSON RESPIRATORY CARE INC., its
                                         Managing Member

                                    By:  _______________________________________
                                         Name:
                                         Title:
                                         Address:

<PAGE>

                                                                   Exhibit 10.16

                                    DEUTSCHE BANK TRUST COMPANY
                                    AMERICAS (f/k/a Bankers Trust
                                    Company), as Collateral Agent,

                                      by

                                          ________________________________
                                          Name:
                                          Title:

<PAGE>

                                                                   Exhibit 10.16
                                                                   Schedule I to
                                                                  Supplement No.
                                                         to the Pledge Agreement

                      Pledged Securities of the New Pledgor
                      -------------------------------------

                                  CAPITAL STOCK

               Number of      Registered       Number and         Percentage of
    Issuer     Certificate      Owner        Class of Shares          Shares
    ------     -----------      -----        ---------------          ------

                                 DEBT SECURITIES

     Issuer           Principal Amount          Date of Note      Maturity Date
     ------           ----------------          ------------      -------------<PAGE>

                                                                   Exhibit 10.17

                    MASTER ASSIGNMENT AND EXCHANGE AGREEMENT

           This Master Assignment and Exchange Agreement (this "Agreement") is
dated as of May 14, 2002 and entered into by and among River Holding Corp., a
Delaware corporation ("Holdings"), Hudson Respiratory Care Inc., a California
corporation ("Borrower"), the financial institutions listed on the signature
pages hereof ("Lenders"), Deutsche Bank Trust Company Americas (formerly named
Bankers Trust Company), as administrative agent for the Lenders (in such
capacity, the "Administrative Agent") and FS Equity Partners IV, L.P., a
Delaware limited partnership ("FSEP IV"), and relates to that certain Credit
Agreement dated as of April 7, 1998 (as amended, supplemented, restated or
otherwise modified to the date hereof (the "Original Credit Agreement") and to
be amended and restated on the date hereof by an Amended and Restated Credit
Agreement dated as of May 14, 2002 (the "Credit Agreement"), among the Borrower,
Holdings, the Lenders and Administrative Agent, Collateral Agent, Swingline
Lender and Issuing Bank. Terms defined in the Credit Agreement are used herein
with the same meanings.

           WHEREAS, each Lender (in such capacity, an "Assignor") desires to
assign such portion of the Term Loans held by such Assignor as is set forth on
Schedule I hereto (the "Purchased Term Loans") to FSEP IV and FSEP IV (in such
capacity, the "Assignee") desires to purchase such Purchased Term Loans from
Assignors; and

           WHEREAS, immediately upon the effectiveness of the assignment of the
Purchased Term Loans to Assignee, Assignee desires to exchange such Purchased
Term Loans for a like principal amount of Borrower's senior unsecured promissory
notes in the form attached hereto as Exhibit A ("Senior Notes") and, upon such
exchange, such Purchased Term Loans shall be cancelled and terminated and shall
no longer constitute Indebtedness outstanding under the Credit Agreement.

           NOW, THEREFORE, in consideration of the premises and the agreements,
provisions and covenants herein contained, the parties hereto agree as follows:

           SECTION 1. Assignment of Purchased Term Loans by Assignors and
Purchase of Purchased Term Loans by FSEP IV.

     A. Each Assignor hereby sells and assigns, without recourse, representation
     or warranty (except as expressly set forth herein) to the Assignee, and the
     Assignee hereby purchases and assumes, without recourse, from such
     Assignor, effective as of the Effective Date set forth below, the Purchased
     Term Loans together with all of such Assignor's rights and obligations
     under the Credit Agreement and other Credit Documents with respect to such
     Purchased Term Loans. Each Assignor represents and warrants that (i) it is
     the legal and beneficial owner of the Term Loans being assigned by it
     hereby free and clear of any adverse claim and (ii) it is legally
     authorized to enter into this Agreement and to carry out the transaction
     contemplated hereby. Assignee represents and warrants that it is legally
     authorized to enter into this Agreement and to carry out the transactions
     contemplated hereby. From and after the Effective Date, except as
     specifically provided in clause 1(B) below, each Assignor shall, to the
     extent of

<PAGE>

                                                                   Exhibit 10.17

     the interests assigned by this Agreement, relinquish its rights and be
     released from its obligations under the Credit Agreement.

     B. In consideration of the assignments described above in Section 1A,
     Assignee hereby agrees to pay to the Administrative Agent for the benefit
     of the Assignors in accordance with their assigned interests set forth on
     Schedule I hereto in immediately available funds, on the Effective Date,
     the total face amount of the Purchased Term Loans. Accrued interest on the
     Purchased Term Loans is being paid to each Assignor on the Effective Date
     pursuant to Section 4.02(h) of the Credit Agreement. Borrower acknowledges
     that Borrower remains liable to each Lender with respect to any amounts
     owing under Section 2.16 of the Credit Agreement to the extent that the
     transactions provided for herein result in the payment of any Eurodollar
     Loan prior to the last day of the Interest Period related thereto.

     C. Notwithstanding anything to the contrary set forth in the Credit
     Agreement, including without limitation any requirement of Section 9.04 as
     to the minimum amount of such assignment, assignments to be comprised of
     the same percentage of Revolving Credit Commitment and Term Loans,
     execution of an Assignment and Acceptance Agreement, recordation of such
     assignment in the Register, notice to Lenders or the payment of any
     processing and recordation fee to Administrative Agent, all of which are
     hereby waived by each of the parties hereto, the parties hereto agree that
     upon the prior or concurrent satisfaction of the conditions set forth in
     Section 2 hereof, the assignment and assumptions provided for herein shall
     become effective in accordance with the terms of this Agreement for all
     purposes of this Agreement and of the Credit Agreement.

           SECTION 2.  Conditions to Effectiveness of Assignment and Purchase of
Purchased Term Loans.

           This Agreement shall become effective upon the prior or concurrent
satisfaction of the following conditions (the date upon which such conditions
are first satisfied is referred to as the "Effective Date"):

     A.    The execution and delivery of this Agreement by each of the parties
     hereto;

     B.    The prior or concurrent satisfaction of the conditions to
     effectiveness of the Credit Agreement as set forth in Section 4.02 thereof;

     C.    The receipt by the Administrative Agent on or before 12:00 noon New
     York City time on the Effective Date, for the account of the Assignors,
     from FSEP IV of an amount equal to the aggregate principal amount of all
     Purchased Term Loans in immediately available funds; and

     D.    The exchange of the Purchased Term Loans for a like principal amount
     of Senior Notes and cancellation for all purposes under the Credit
     Agreement and other Credit Documents of such Purchased Term Loans pursuant
     to Section 3 hereof.

                                       2

<PAGE>

                                                                   Exhibit 10.17

          SECTION 3. Exchange and Cancellation.

          Concurrently with the effectiveness of this Agreement, Assignee and
Borrower agree that Assignee will exchange the Purchased Term Loans for
$12,000,000 in principal amount of Senior Notes issued by Borrower, and Borrower
agrees to issue $12,000,000 in aggregate principal amount of Senior Notes, dated
the Effective Date and accruing interest at the rate per annum provided for in
such Senior Notes. Upon the issuance of such Senior Notes, the Purchased Term
Loans shall be cancelled and the Indebtedness represented by such Purchased Term
Loans shall be deemed paid and no longer outstanding under the Credit Agreement
for any purpose whatsoever. Each of the parties hereto agrees that
notwithstanding anything to the contrary in the Credit Agreement, that such
cancellation and payment of the Indebtedness represented by the Purchased Term
Loans shall be applied under the Original Credit Agreement as follows: first, to
the payment of the $2,000,000 principal installment on the Term Loans due on
March 31, 2002; second, of the remaining $10,000,000 in Purchased Term Loans,
$5,000,000 in the aggregate shall be applied to prepay one-half of each of the
$2,500,000 principal installments due on the Term Loans under the Original
Credit Agreement on June 30, 2002, September 30, 2002, December 31, 2002 and
March 31, 2003; and third, the remaining $5,000,000 shall be applied to prepay
$5,000,000 of the $10,000,000 principal installment due on the Term Loans under
the Original Credit Agreement on June 30, 2003. Assignee will have no rights
under any of the Credit Documents with respect to the Senior Notes.

          SECTION 4. Miscellaneous.

     A.   This Agreement shall be governed by and construed in accordance with
     the laws of the State of New York.

     B.   Each party to this Agreement hereby agrees from time to time, upon the
     request of the other parties hereto, to take such additional actions and to
     execute and deliver such additional documents and instruments as such other
     party may reasonably request to effect the transactions contemplated by,
     and to carry out the intent of this Agreement.

     C.   Neither this Agreement nor any term hereof may be changed, waived,
     discharged or terminated, except by an instrument in writing signed by the
     party against whom enforcement of such change, waiver, discharge or
     termination is sought.

     D.   All communications and notices hereunder shall be in writing and given
     as provided in Section 9.01 of the Credit Agreement. All communications and
     notices hereunder to FSEP IV shall be given to it at the address for
     notices set forth below:

          FS Equity Partners IV, L.P.
          C/o Freeman Spogli & Co. LLC
          11100 Santa Monica Boulevard
          Los Angeles, California 90025
          Attn: Jon D. Ralph
          Telecopy:  (310) 444-1870

     E.   In case any provision in or obligation under this Agreement shall be
     invalid, illegal or unenforceable in any jurisdiction, the validity,
     legality and enforceability of the

                                       3

<PAGE>

                                                                   Exhibit 10.17

     remaining provisions or obligations, or of such provision or obligation in
     any other jurisdiction, shall not in any way be affected or impaired
     thereby.

     F.   This Agreement shall be binding upon, and shall inure to the benefit
     of, the parties hereto and their respective successors and assigns.

     G.   This Agreement may be executed in counterparts (and by different
     parties hereto on different counterparts), each of which shall constitute
     an original but all of which when taken together shall constitute a single
     contract. Delivery of an executed signature page to this Agreement by
     telecopy transmission shall be as effective as delivery of a manually
     signed counterpart of this Agreement.

                  [remainder of page intentionally left blank]

                                       4

<PAGE>

                                                                   Exhibit 10.17

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be executed as of the date first above written by their respective duly
authorized officers.

                                        RIVER HOLDING CORP.

                                        By:___________________________
                                        Title:

                                        HUDSON RESPIRATORY CARE INC.

                                        By:___________________________
                                        Title:

                                        FS EQUITY PARTNERS IV, L.P., as Assignee

                                        By:  FS Capital Partners, LLC
                                        Its:  General Partner

                                        By:___________________________
                                        Title:

                                       S-1

<PAGE>

                                                                   Exhibit 10.17

                                        DEUTSCHE BANK TRUST COMPANY
                                        AMERICAS, as Administrative Agent and
                                        Assignor

                                        By:___________________________
                                        Title:

                                       S-2

<PAGE>

                                                                   Exhibit 10.17

                                        ASSIGNORS:

                                        DEUTSCHE BANK TRUST COMPANY
                                        AMERICAS

                                        By:   __________________________________
                                        Name:
                                        Title:

                                        BANK AUSTRIA CREDITANSTALT
                                        CORPORATE FINANCE, INC.

                                        By:   __________________________________
                                        Name:
                                        Title:

                                        By:   __________________________________
                                        Name:
                                        Title:

                                       S-3

<PAGE>

                                                                   Exhibit 10.17

                                        BANK OF AMERICA, N.A.

                                        By:   __________________________________
                                        Name:
                                        Title:

                                       S-4

<PAGE>

                                                                   Exhibit 10.17

                                        BANK OF TOKYO-MITSUBISHI
                                        TRUST COMPANY

                                        By:   __________________________________
                                        Name:
                                        Title:

                                       S-5

<PAGE>
                                                                   Exhibit 10.17

                                          PB CAPITAL CORPORATION

                                          By:   ______________________________
                                          Name:
                                          Title:

                                          By:   ______________________________
                                          Name:
                                          Title:

                                       S-6

<PAGE>
                                                                   Exhibit 10.17

                                                 CITICORP USA, INC.

                                                 By:   ________________________
                                                 Name:
                                                 Title:

                                       S-7

<PAGE>
                                                                   Exhibit 10.17

                                                 IMPERIAL BANK

                                                 By:  _________________________
                                                 Name:
                                                 Title:

                                       S-8

<PAGE>
                                                                   Exhibit 10.17

                                               ROYAL BANK OF CANADA

                                               By:  ____________________________
                                               Name:
                                               Title:

                                       S-9

<PAGE>

                                                                   Exhibit 10.17

                                       SOCIETE GENERALE

                                       By:    _________________________
                                       Name:
                                       Title:

                                      S-10

<PAGE>

                                                                   Exhibit 10.17

                                         WELLS FARGO BANK, N.A.

                                         By:    _______________________
                                         Name:
                                         Title:

                                      S-11

<PAGE>

                                                                   Exhibit 10.17

                                   SCHEDULE I

<TABLE>
<CAPTION>
                                                   Principal Amount                 Percentage
                                                       of Term                   of Aggregate Term
Assignor                                            Loans Assigned                 Loans Assigned
--------                                            --------------                 --------------
<S>                                                <C>                             <C>
Deutsche Bank Trust Company
Americas (f/k/a Bankers Trust
Company)                                           $   887,755.11                       4.04%
Bank of America, N.A.                                2,400,000.00                      10.91
Bank Austria Creditanstalt Corporate
Finance, Inc.                                        1,200,000.00                       5.45
Bank of Tokyo-Mitsubishi Trust
Company                                              1,200,000.00                       5.45
Citicorp USA, Inc.                                   1,500,000.00                       6.82
Imperial Bank                                          612,244.89                       2.78
PB Capital Corporation                                 900,000.00                       4.09
Royal Bank of Canada                                   900,000.00                       4.09
Societe Generale                                     1,200,000.00                       5.45
Wells Fargo Bank, N.A.                               1,200,000.00                       5.45
                                                   ==============                  =========
TOTAL:                                             $12,000,000.00                      54.55%*
</TABLE>

     *Total may not foot due to rounding.

                                   Schedule-1

<PAGE>

                                                                   Exhibit 10.17

                                    EXHIBIT A

                              [Attach Senior Note]

                                     Annex-1

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