<PAGE>

                                                                   EXHIBIT 10.23

                             SECURED PROMISSORY NOTE

$250,000,000.00                                                     July 1, 2003

         FOR VALUE RECEIVED, the undersigned, American HomePatient, Inc., a
Delaware corporation, American HomePatient, Inc., a Tennessee corporation,
Designated Companies, Inc., AHP Finance, Inc., American HomePatient of New York,
Inc., National Medical Systems, Inc., Sound Medical Equipment, Inc., The
National Medical Rentals, Inc., National I.V., Inc., American HomePatient of
Arkansas, Inc., American HomePatient of Nevada, Inc., Volunteer Medical Oxygen &
Hospital Equipment Co., Allegheny Respiratory Associates, Inc., American
HomePatient of Illinois, Inc., American HomePatient of Texas, L.P., AHP, L.P.,
AHP Home Medical Equipment Partnership of Texas, Colorado Home Medical Equipment
Alliance, LLC, Northeast Pennsylvania Alliance, LLC, Northwest Washington
Alliance, LLC, AHP Home Care Alliance of Tennessee, AHP Alliance of Columbia,
AHP Knoxville Partnership, AHP Home Care Alliance of Gainesville, AHP Home Care
Alliance of Virginia (individually and collectively, "Makers"), jointly and
severally promise to pay to BANK OF MONTREAL (Bank of Montreal or its duly
appointed successor being referred to herein as the "Agent"), as agent for each
of the lender's listed on Schedule 1 hereto, as such schedule is amended from
time to time hereafter by Agent (each individually, a "Payee" and collectively,
the "Payees"; the Payees and any subsequent holders hereof are hereinafter
referred to collectively as the "Holders"), at the office of Agent located at
115 S. LaSalle Street, 12 W, Chicago, Illinois 60603 (attention: Heather Turf)
or at such other place as Agent may designate to Maker in writing from time to
time, the principal sum of TWO HUNDRED FIFTY MILLION AND NO/100THS DOLLARS
($250,000,000.00), together with interest on the outstanding principal balance
hereof from the date hereof at the rate of 6.785 percent (6.785%) per annum
(computed on the basis of a 360-day year). All capitalized terms used but not
defined herein shall have the meaning given to such terms in the Second Amended
Joint Plan of Reorganization for Maker dated January 2, 2003 (as amended from
time to time thereafter, the "Plan of Reorganization").

         Interest only on the outstanding principal balance hereof shall be due
and payable monthly, in arrears, with the first installment being payable on the
first (1st) day of August, 2003, and subsequent installments being payable on
the first (1st) business day of each succeeding month thereafter until August 1,
2009 (the "Maturity Date"), at which time the entire outstanding principal
balance, together with all accrued and unpaid interest, shall be immediately due
and payable in full.

         Prior to the Maturity Date, Maker shall, in addition to the payments
required above, make periodic payments of principal (the "Mandatory
Pre-Payments") to Agent, on behalf of the Holders, as follows: (i) until the
Class 5 and Class 8 Claimants are paid in full, for the fiscal years ending
December 31, 2004 and thereafter, Maker shall make principal payments hereunder
equal to one-third (1/3) of the amount of cash (as determined by Maker's
independent auditors) in excess of $7,000,000 that is available to Maker as of
the end of such year after accounting for all of Maker's

<PAGE>

expenditures and expenses during that calendar year, including without
limitation a reserve for payment of any Contested Claims, and (ii) after the
Class 5 and Class 8 Claimants are paid in full, for the fiscal years ending
prior to maturity, Maker shall make principal payments hereunder equal to 100%
of the amount of cash (as determined by Maker's independent auditors) in excess
of $7,000,000 that is available to Maker as of the end of such year after
accounting for all of Maker's expenditures and expenses during that calendar
year, including without limitation a reserve for payment of any Contested
Claims. All determinations of excess cash flow made by the Maker's independent
auditors shall be final, conclusive, and binding on Maker and Holders absent
manifest error.

         Any Mandatory Pre-Payments shall be paid in full to Agent, on behalf of
the Holders, by no later than March 31 of the year following the fiscal year
with respect to which such payments are required; provided, however, that Maker
shall make an estimated payment related to the Mandatory Pre-Payments on
September 30 of each fiscal year commencing September 30, 2004. The estimated
payment shall be in an amount equal to one-half (1/2) of Maker's good-faith
estimate of the Required Pre-Payments for such fiscal year based on Maker's cash
on hand at June 30 and anticipated cash needs during the remainder of the fiscal
year.

         The indebtedness evidenced hereby may be prepaid in whole or in part,
at any time and from time to time, without premium or penalty. Any such
prepayments shall be credited first to any accrued and unpaid interest and then
to the outstanding principal balance hereof.

         Time is of the essence of this Note.

         In the event this Note is placed in the hands of an attorney for
collection, or if Holder incurs any external costs incident to the collection of
the indebtedness evidenced hereby, Maker and any endorsers hereof agree to pay
to Holder an amount equal to all such costs, including without limitation all
reasonable attorneys' fees and all court costs.

         Presentment for payment, demand, protest and notice of demand, protest
and nonpayment are hereby waived by Maker and all other parties hereto. No
failure to accelerate the indebtedness evidenced hereby by reason of an Event of
Default hereunder, acceptance of a past-due installment or other indulgences
granted from time to time, shall be construed as a novation of this Note or as a
waiver of such right of acceleration or of the right of Holder thereafter to
insist upon strict compliance with the terms of this Note or to prevent the
exercise of such right of acceleration or any other right granted hereunder or
by applicable law. No extension of the time for payment of the indebtedness
evidenced hereby or any installment due hereunder, made by agreement with any
person now or hereafter liable for payment of the indebtedness evidenced hereby,
shall operate to release, discharge, modify, change or affect the original
liability of Maker hereunder or that of any other person now or hereafter liable
for payment of the indebtedness evidenced hereby, either in whole or in part,
unless Holder agrees otherwise in writing. This Note may not be changed orally,
but only by an agreement in writing signed by the party(ies) against whom
enforcement of any waiver, change, modification or discharge is sought.

                                       2
<PAGE>

         The indebtedness and other obligations evidenced by this Note are
further evidenced by (i) the Plan of Reorganization and (ii) all other documents
evidencing the Holders' security interests and liens on property of Maker.

         All agreements herein made are expressly limited so that in no event
whatsoever shall the amount paid or agreed to be paid to Holder for the use of
the money advanced or to be advanced hereunder exceed the maximum rate of
interest allowed to be charged under applicable law (the "Maximum Rate"). If,
from any circumstances whatsoever, the fulfillment of any provision of this Note
or any other agreement or instrument now or hereafter evidencing, securing or in
any way relating to the indebtedness evidenced hereby shall involve the payment
of interest in excess of the Maximum Rate, then, ipso facto, the obligation to
pay interest hereunder shall be reduced to the Maximum Rate; and if from any
circumstance whatsoever, Holder shall ever receive interest, the amount of which
would exceed the amount collectible at the Maximum Rate, such amount as would be
excessive interest shall be applied to the reduction of the principal balance
remaining unpaid hereunder and not to the payment of interest. This provision
shall control every other provision in any and all other agreements and
instruments existing or hereafter arising between Maker and Holder with respect
to the indebtedness evidenced hereby.

         This Note is intended as a contract under and shall be construed and
enforceable in accordance with the laws of the State of Tennessee, except to the
extent that federal law may be applicable to the determination of the Maximum
Rate.

         Failure by Maker to pay to Agent on behalf of Holders any amounts due
hereunder within ten (10) business days of the due date thereof shall constitute
an Event of Default hereunder.

         MAKER HEREBY IRREVOCABLY CONSENTS TO THE JURISDICTION OF THE UNITED
STATES DISTRICT COURT FOR THE MIDDLE DISTRICT OF TENNESSEE AND OF ALL TENNESSEE
STATE COURTS SITTING IN DAVIDSON COUNTY, TENNESSEE, FOR THE PURPOSE OF ANY
LITIGATION TO WHICH HOLDER MAY BE A PARTY AND WHICH CONCERNS THIS NOTE. IT IS
FURTHER AGREED THAT VENUE FOR ANY SUCH ACTION SHALL LIE EXCLUSIVELY WITH COURTS
SITTING IN DAVIDSON COUNTY, TENNESSEE.

         HOLDER AND MAKER HEREBY KNOWINGLY AND VOLUNTARILY WITH THE BENEFIT OF
COUNSEL WAIVE TRIAL BY JURY IN ANY ACTIONS, PROCEEDINGS, CLAIMS OR
COUNTER-CLAIMS, WHETHER IN CONTRACT OR TORT OR OTHERWISE, AT LAW OR IN EQUITY,
ARISING OUT OF OR IN ANY WAY RELATING TO THIS AGREEMENT.

                                       3
<PAGE>

         As used herein, the terms "Maker" and "Holder" shall be deemed to
include their respective successors, legal representatives and assigns, whether
by voluntary action of the parties or by operation of law.

                                          MAKER:

                                          AMERICAN HOMEPATIENT, INC.,
                                          a Delaware corporation

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          AMERICAN HOMEPATIENT, INC.,
                                          a Tennessee corporation

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          DESIGNATED COMPANIES, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          AHP FINANCE, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          AMERICAN HOMEPATIENT OF NEW YORK, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                       4
<PAGE>

                                          NATIONAL MEDICAL SYSTEMS, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          SOUND MEDICAL EQUIPMENT, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          THE NATIONAL MEDICAL RENTALS, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          NATIONAL I.V., INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          AMERICAN HOMEPATIENT OF ARKANSAS,
                                          INC.,

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          AMERICAN HOMEPATIENT OF NEVADA, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          VOLUNTEER MEDICAL OXYGEN &
                                          HOSPITAL EQUIPMENT CO.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                       5
<PAGE>

                                          ALLEGHENY RESPIRATORY ASSOCIATES, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          AMERICAN HOMEPATIENT OF ILLINOIS, INC.

                                          By:    /s/ Robert L. Fringer
                                          Title: Vice President & Secretary

                                          AMERICAN HOMEPATIENT OF TEXAS, L.P.,
                                          a Texas limited partnership

                                          By: AMERICAN HOMEPATIENT, INC.,
                                              its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT OF ILLINOIS,
                                              INC., its limited partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          AHP, L.P.,
                                          a Tennessee limited partnership

                                          By: AMERICAN HOMEPATIENT, INC.,
                                              its general partner

                                       6
<PAGE>

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT OF ILLINOIS,
                                              INC., its  limited partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          AHP HOME MEDICAL EQUIPMENT
                                          PARTNERSHIP OF TEXAS,
                                          a Texas general partnership

                                          By: AHP, L.P.,
                                              a general partner

                                              By:    AMERICAN HOMEPATIENT, INC.,
                                                     its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC., a general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          COLORADO HOME MEDICAL EQUIPMENT
                                          ALLIANCE, LLC,
                                          a Colorado limited liability company

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC., its sole member

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                       7
<PAGE>

                                          NORTHEAST PENNSYLVANIA ALLIANCE, LLC,
                                          a Pennsylvania limited liability
                                          company

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC. its sole member

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          NORTHWEST WASHINGTON ALLIANCE, LLC,
                                          a Washington limited liability company

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC. its sole member

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          AHP HOME CARE ALLIANCE OF TENNESSEE,
                                          a Tennessee general partnership

                                          By: AMERICAN HOMEPATIENT, INC.,
                                              its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC., its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                       8
<PAGE>

                                          AHP ALLIANCE OF COLUMBIA,
                                          a South Carolina general partnership

                                          By: AMERICAN HOMEPATIENT, INC.,
                                              its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC., its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          AHP KNOXVILLE PARTNERSHIP,
                                          a Tennessee general partnership

                                          By: AMERICAN HOMEPATIENT, INC.,
                                              its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC., its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                       9
<PAGE>

                                          AHP HOME CARE ALLIANCE OF GAINESVILLE,
                                          a Florida general partnership

                                          By: AMERICAN HOMEPATIENT, INC.,
                                              its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC., its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          AHP HOME CARE ALLIANCE OF VIRGINIA,
                                          a Virginia general partnership

                                          By: AMERICAN HOMEPATIENT, INC.,
                                              its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                          By: AMERICAN HOMEPATIENT VENTURES,
                                              INC., its general partner

                                              By:    /s/ Robert L. Fringer
                                              Title: Vice President & Secretary

                                       10
<PAGE>

                                   SCHEDULE 1
                                     LENDERS

                                       11