<PAGE>

                                                                 EXHIBIT 10.30.3


                                                August 27, 2004




Allied HealthCare Products, Inc.
1720 Sublette Avenue
St. Louis, Missouri 63110

         RE: THIRD AMENDMENT-(REVISED)

Gentlemen:

         ALLIED HEALTHCARE PRODUCTS, INC., a Delaware corporation ("BORROWER")
and LASALLE BANK NATIONAL ASSOCIATION, a national banking association ("LENDER")
have entered into that certain Loan and Security Agreement dated April 24, 2002
(the "SECURITY AGREEMENT"). From time to time thereafter, Borrower and Lender
may have executed various amendments (each an "AMENDMENT" and collectively the
"AMENDMENTS") to the Security Agreement (the Security Agreement and the
Amendments hereinafter are referred to, collectively, as the "AGREEMENT").
Borrower and Lender now desire to further amend the Agreement as provided
herein, subject to the terms and conditions hereinafter set forth.

                  NOW, THEREFORE, in consideration of the foregoing recitals,
the mutual covenants and agreements set forth herein and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto hereby agree as follows:

         1.       The Agreement hereby is amended as follows:

         (a)      The definition in Paragraph 1 of the Agreement entitled
                  "MAXIMUM LOAN LIMIT" shall mean Twelve Million Thirty Thousand
                  Eight Hundred Sixty and 25/100 Dollars ($12,030,860.25).

         (b) Subsection 2(a) of the Agreement is deleted in its entirety and the
following is substituted in its place:

             (a) REVOLVING LOANS.


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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 2

                  Subject to the terms and conditions of this Agreement and the
                  Other Agreements, during the Original Term and any Renewal
                  Term, Lender shall, absent the occurrence of an Event of
                  Default, make revolving loans and advances (the "REVOLVING
                  LOANS") in an amount up to the sum of the following sublimits
                  (the "REVOLVING LOAN LIMIT"):

                  (i)      Up to eighty percent (80%) of the face amount (less
                           the maximum discounts, credits and allowances which
                           may be taken by or granted to Account Debtors in
                           connection therewith in the ordinary course of
                           Borrower's business) of Borrower's Eligible Accounts;
                           plus

                  (ii)     Up to fifty percent (50%) of the lower of the cost or
                           market value of Borrower's Eligible Inventory or
                           Seven Million and No/100 Dollars ($7,000,000.00),
                           whichever is less; minus

                  (iii)    Such reserves as Lender elects, in its reasonable
                           discretion, exercised in good faith, to establish
                           from time to time, including, without limitation, a
                           reserve with respect to Interest Rate Protection
                           Agreement Obligations;

                  provided, that the Revolving Loan Limit shall in no event
                  exceed Ten Million and No/100 Dollars ($10,000,000.00) (the
                  "MAXIMUM REVOLVING LOAN LIMIT") except as such amount may be
                  decreased by Lender following the occurrence of an Event of
                  Default.

                  The aggregate unpaid principal balance of the Revolving Loans
                  shall not at any time exceed the lesser of the (i) Revolving
                  Loan Limit minus the Letter of Credit Obligations and (ii) the
                  Maximum Revolving Loan Limit minus the Letter of Credit
                  Obligations. If at any time the outstanding


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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 3

                  Revolving Loans exceeds either the Revolving Loan Limit or the
                  Maximum Revolving Loan Limit, in each case minus the Letter of
                  Credit Obligations, or any portion of the Revolving Loans and
                  Letter of Credit Obligations exceeds any applicable sublimit
                  within the Revolving Loan Limit, Borrower shall immediately,
                  and without the necessity of demand by Lender, pay to Lender
                  such amount as may be necessary to eliminate such excess and
                  Lender shall apply such payment to the Revolving Loans to
                  eliminate such excess.


                  Amounts borrowed pursuant to this subsection 2(a) may be
                  repaid by Borrower, and, subject to the terms and conditions
                  of this Agreement and the Other Agreements, reborrowed at any
                  time during the Original Term and any Renewal Term.

                  Borrower hereby authorizes Lender, in its sole discretion, to
                  charge any of Borrower's accounts or advance Revolving Loans
                  to make any payments of principal, interest, fees, costs or
                  expenses required to be made under this Agreement or the Other
                  Agreements.

                  A request for a Revolving Loan shall be made or shall be
                  deemed to be made, each in the following manner: Borrower
                  shall give Lender same day notice, no later than 10:30 A.M.
                  (Chicago time) for such day, of its request for a Revolving
                  Loan as a Prime Rate Loan, and at least three (3) Business
                  Days prior notice of its request for a Revolving Loan as a
                  LIBOR Rate Loan, in which notice Borrower shall specify the
                  amount of the proposed borrowing and the proposed borrowing
                  date; provided, however, that no such request may be made at a
                  time when there exists an Event of Default or an event which,
                  with the passage of time or giving of notice, will become an
                  Event of Default. In the event that Borrower maintains a
                  controlled disbursement account at Lender, each check
                  presented for payment against such controlled disbursement
                  account and any other

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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 4


                  charge or request for payment against such controlled
                  disbursement account shall constitute a request for a
                  Revolving Loan as a Prime Rate Loan. As an accommodation to
                  Borrower, Lender may permit telephone requests for Revolving
                  Loans and electronic transmittal of instructions,
                  authorizations, agreements or reports to Lender by Borrower.
                  Unless Borrower specifically directs Lender in writing not to
                  accept or act upon telephonic or electronic communications
                  from Borrower, Lender shall have no liability to Borrower for
                  any loss or damage suffered by Borrower as a result of
                  Lender's honoring of any requests, execution of any
                  instructions, authorizations or agreements or reliance on any
                  reports communicated to it telephonically or electronically
                  and purporting to have been sent to Lender by Borrower and
                  Lender shall have no duty to verify the origin of any such
                  communication or the authority of the Person sending it,
                  except in the event of Lender's willful misconduct or gross
                  negligence.

                  Borrower hereby irrevocably authorizes Lender to disburse the
                  proceeds of each Revolving Loan requested by Borrower, or
                  deemed to be requested by Borrower, as follows: the proceeds
                  of each Revolving Loan requested under Section 2(a) shall be
                  disbursed by Lender in lawful money of the United States of
                  America in immediately available funds, in the case of the
                  initial borrowing, in accordance with the terms of the written
                  disbursement letter from Borrower, and in the case of each
                  subsequent borrowing, by wire transfer or Automated Clearing
                  House (ACH) transfer to such bank account as may be agreed
                  upon by Borrower and Lender from time to time, or elsewhere if
                  pursuant to a written direction from Borrower.

         (c) Subsection 4(a) of the Agreement is deleted in its entirety and the
following is substituted in its place:

                  4. INTEREST, FEES, AND CHARGES.


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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 5

                  (a)      INTEREST RATE: Subject to the terms and conditions
                           set forth below, the Loans shall bear interest at the
                           per annum rate of interest of the Prime Rate plus the
                           Prime Margin set forth below or at the LIBOR Rate
                           plus the LIBOR Margin set forth below, at Borrower's
                           option, based on the following matrix. Initially, the
                           Loans shall bear interest as reflected in Level II of
                           the matrix from and after August 3, 2004 until the
                           date Borrower submits its fiscal year 2004 audited
                           financial statements, at which time the rate of
                           interest shall be reset within five (5) Business Days
                           of Lenders receipt and shall be tested quarterly by
                           Lender thereafter and, if applicable, reset by Lender
                           within five (5) Business Days of Lender's receipt of
                           Borrower's quarterly financial statements.

<Table>
<Caption>
                                                 ALL LOANS
                                --------------------------------------------
              FUNDED DEBT
   LEVEL      TO EBITDA         LIBOR MARGIN                    PRIME MARGIN
   -----      -----------       ------------                    ------------
<S>           <C>               <C>                             <C>
     I           > 3.0             300 bps                         0.75%
                 -

    II       >2.25 and <3.0        275 bps                         0.50%
             -

    III      >1.5 and <2.25        250 bps                         0.25%
             -

    IV            <1.5             225 bps                         0.00%
</Table>


                           "Funded Debt" shall mean, with respect to any period,
                           all debt of Borrower for borrowed money,



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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 6


                           whether or not evidenced by bonds, debentures, notes
                           or similar instruments.

                           With respect to the Prime Rate Loans, the interest
                           rate shall increase or decrease by an amount equal to
                           each increase or decrease in the Prime Rate effective
                           on the effective date of each such change in the
                           Prime Rate. Interest on Prime Rate Loans shall be
                           payable on the last Business Day of each month in
                           arrears.

                           With respect to LIBOR Rate Loans, the interest rate
                           shall remain fixed for the applicable Interest
                           Period. "Interest Period" shall mean any continuous
                           period of thirty (30), sixty (60), ninety (90) days,
                           or one hundred eighty (180) days, as selected from
                           time to time by Borrower by irrevocable notice (in
                           writing, by telecopy, electronic mail, telex,
                           telegram or cable) given to Bank not less than three
                           (3) Business Days prior to the first day of each
                           respective Interest Period; provided that: (i) each
                           such period occurring after such initial period shall
                           commence on the day on which the immediately
                           preceding period expires; (ii) the final Interest
                           Period shall be such that its expiration occurs on or
                           before the end of the Original Term or any Renewal
                           Term; and (iii) if for any reason Borrower shall fail
                           to timely select a period, then such Loans shall
                           continue as, or revert to, Prime Rate Loans. Interest
                           shall be payable on the last Business Day of each
                           month and on the date of any payment hereon by
                           Borrower. Interest shall be payable on the last
                           Business Day of each month in arrears and on the last
                           Business Day of the applicable Interest Period.

                           Upon the occurrence of an Event of Default, the Loans
                           shall bear interest at the rate of two percent (2.0%)
                           per annum in excess of the interest rate otherwise
                           payable thereon, which interest shall be payable on
                           demand. All interest shall be calculated on the basis
                           of a 360-day year.


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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 7


         (d) Subparagraph (4)(b) of the Agreement is deleted in its entirety and
the following is substituted in its place.

                  (b) OTHER LIBOR PROVISIONS.

                           (i) Subject to the provisions of this Agreement,
                           Borrower shall have the option (A) as of any date, to
                           convert all or any part of the Prime Rate Loans to,
                           or request that new Loans be made as, LIBOR Rate
                           Loans of various Interest Periods; (B) as of the last
                           day of any Interest Period, to continue all or any
                           portion of the relevant LIBOR Rate Loans as LIBOR
                           Rate Loans; (C) as of the last day of any Interest
                           Period, to convert all or any portion of the LIBOR
                           Rate Loans to Prime Rate Loans; and (D) at any time,
                           to request new Loans as Prime Rate Loans; provided,
                           that Loans may not be continued as or converted to
                           LIBOR Rate Loans, if the continuation or conversion
                           thereof would violate the provisions of subsections
                           4(b)(ii) or 4(b)(iii) of this Agreement or if an
                           Event of Default has occurred and is continuing.

                           (ii) Lender's determination of the LIBOR Rate as
                           provided above shall be conclusive, absent manifest
                           error. Furthermore, if Lender determines, in good
                           faith (which determination shall be conclusive,
                           absent manifest error), prior to the commencement of
                           any Interest Period that (A) U.S. Dollar deposits of
                           sufficient amount and maturity for funding the Loans
                           are not available to Lender in the London Interbank
                           Eurodollar market in the ordinary course of business,
                           or (B) by reason of circumstances affecting the
                           London Interbank Eurodollar market, adequate and fair
                           means do not exist for ascertaining the rate of
                           interest to be applied to the Loans requested by
                           Borrower to be LIBOR Rate Loans or the Loans bearing
                           interest at the rates set forth in subsection
                           4(a)(ii) of this Agreement shall not represent the
                           effective pricing to Lender for U.S. Dollar deposits
                           of a comparable amount for the relevant period (such
                           as for example, but not limited to, official reserve

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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 8

                           requirements required by Regulation D to the extent
                           not given effect in determining the rate), Lender
                           shall promptly notify Borrower and (1) all existing
                           LIBOR Rate Loans shall convert to Prime Rate Loans
                           upon the end of the applicable Interest Period, and
                           (2) no additional LIBOR Rate Loans shall be made
                           until such circumstances are cured.

                           (iii) If, after the date hereof, the introduction of,
                           or any change in any applicable law, treaty, rule,
                           regulation or guideline or in the interpretation or
                           administration thereof by any governmental authority
                           or any central bank or other fiscal, monetary or
                           other authority having jurisdiction over Lender or
                           its lending offices (a "Regulatory Change"), shall,
                           in the opinion of counsel to Lender, make it unlawful
                           for Lender to make or maintain LIBOR Rate Loans, then
                           Lender shall promptly notify Borrower and (A) the
                           LIBOR Rate Loans shall immediately convert to Prime
                           Rate Loans on the last Business Day of the then
                           existing Interest Period or on such earlier date as
                           required by law, and (B) no additional LIBOR Rate
                           Loans shall be made until such circumstance is cured.

                           (iv) If, for any reason, a LIBOR Rate Loan is paid
                           prior to the last Business Day of any Interest Period
                           or if a LIBOR Rate Loan does not occur on a date
                           specified by Borrower in its request (other than as a
                           result of a default by Lender), Borrower agrees to
                           indemnify Lender against any loss (including any loss
                           on redeployment of the deposits or other funds
                           acquired by Lender to fund or maintain such LIBOR
                           Rate Loan), cost or expense incurred by Lender as a
                           result of such prepayment.

                           (v) If any Regulatory Change (whether or not having
                           the force of law) shall (A) impose, modify or deem
                           applicable any assessment, reserve, special deposit
                           or similar requirement against assets held by, or
                           deposits in or for the account of or loans by, or any
                           other acquisition of funds or disbursements by,
                           Lender with respect to Borrower; (B) subject


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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 9

                           Lender or the LIBOR Rate Loans to any Tax or change
                           the basis of taxation of payments to Lender of
                           principal or interest due from Borrower to Lender
                           hereunder (other than a change in the taxation of the
                           overall net income of Lender); or (C) impose on
                           Lender any other condition regarding the LIBOR Rate
                           Loans or Lender's funding thereof, and Lender shall
                           determine (which determination shall be conclusive,
                           absent any manifest error) that the result of the
                           foregoing is to increase materially the cost to
                           Lender of making or maintaining the LIBOR Rate Loans
                           or to reduce materially the amount of principal or
                           interest received by Lender hereunder, then Borrower
                           shall pay to Lender, on demand, such additional
                           amounts as Lender shall, from time to time, determine
                           are sufficient to compensate and indemnify Lender
                           from such increased cost or reduced amount.

                           (vi) Lender shall receive payments of amounts of
                           principal and interest with respect to the LIBOR Rate
                           Loans free and clear of, and without deduction for,
                           any Taxes. If (A) Lender shall be subject to any Tax
                           in respect of any LIBOR Rate Loans or any part
                           thereof, or (B) Borrower shall be required to
                           withhold or deduct any Tax from any such amount, the
                           LIBOR Rate applicable to such LIBOR Rate Loans shall
                           be adjusted by Lender to reflect all additional costs
                           incurred by Lender in connection with the payment by
                           Lender or the withholding by Borrower of such Tax and
                           Borrower shall provide Lender with a statement
                           detailing the amount of any such Tax actually paid by
                           Borrower. Determination by Lender of the amount of
                           such costs shall be conclusive, absent manifest
                           error. If after any such adjustment any part of any
                           Tax paid by Lender is subsequently recovered by
                           Lender, Lender shall reimburse Borrower to the extent
                           of the amount so recovered. A certificate of an
                           officer of Lender setting forth the amount of such
                           recovery and the basis therefor shall be conclusive,
                           absent manifest error.


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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 10

                           (vii) Each request for LIBOR Rate Loans shall be in
                           an amount not less than One Million and No/100
                           Dollars ($1,000,000.00), and in integral multiples of
                           One Hundred Thousand and No/100 Dollars
                           ($100,000.00).

                           (viii) Unless otherwise specified by Borrower, all
                           Loans shall be Prime Rate Loans.

                           (ix) No more than five (5) Interest Periods may be in
                           effect with respect to outstanding LIBOR Rate Loans
                           at any one time.

         (e) Subsection (4)(c)(ii) of the Agreement entitled "Amendment Fee" is
deleted in its entirety and the phrase "Intentionally Omitted" is substituted in
its place.

         (f) Subsection (4)(c)(vi) of the Agreement is deleted in its entirety
and the following is substituted in its place:

                  (VI)     TRANSACTION FEE: Borrower shall pay to Lender a
                           transaction fee of Five Hundred and No/100 Dollars
                           ($500.00), which fee shall be fully earned by Lender
                           and payable to Lender upon execution of the Amendment
                           dated August 3, 2004.

         (g) Subsection 4(c)(vii) of the Agreement is amended to add the
following provision:

                  (VII)    EXTENSION FEE: Borrower shall pay to Lender an
                           extension fee of Ten Thousand and No/100 Dollars
                           ($10,000.00), which fee shall be fully earned by
                           Lender and payable to Lender upon execution of the
                           Amendment dated August 3, 2004.

         (h) The first grammatical sentence of Paragraph (10) of the Agreement
is amended as follows:

                  (10)     ORIGINAL TERM: The date of the Original Term set
                           forth in paragraph 10 of the Agreement is deleted and
                           the date of April 24, 2007 is substituted in its
                           place.


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ALLIED HEALTHCARE PRODUCTS, INC.
August 27, 2004
Page 11

         (i) Paragraph 14(d) of the Agreement is deleted in its entirety and the
following is substituted in its place:

                  (d)      CAPITAL EXPENDITURE LIMITATIONS.

                           Borrower shall not make any Capital Expenditures if,
                           after giving effect to such Capital Expenditure, the
                           aggregate cost of all such fixed assets purchased or
                           otherwise acquired would exceed (i) $2,000,000.00 for
                           Fiscal Year ending June 30, 2005; and (ii) thereafter
                           $1,000,000.00 during any Fiscal Year.

         2. This Amendment shall not become effective until fully executed by
all parties hereto.

         3. Except as expressly amended hereby and by any other supplemental
documents or instruments executed by either party hereto in order to effectuate
the transactions contemplated hereby, the Agreement hereby is ratified and
confirmed by the parties hereto and remains in full force and effect in
accordance with the terms thereof.

                                      LASALLE BANK NATIONAL ASSOCIATION

                                      By
                                        ---------------------------------------

                                      Title
                                           ------------------------------------

ACKNOWLEDGED AND AGREED TO
this 27TH day of AUGUST, 2004:

ALLIED HEALTHCARE PRODUCTS, INC.

By
  --------------------------------
     EARL R. REFSLAND

Title: PRESIDENT