<PAGE>   1
[HEALTHDYNE LOGO]                                                  EXHIBIT 10.37


January 27, 1994


Mr. Robert M. Johnson
4160 Coralee Lane
Lafayette, California 94549

Re:  Offer of Employment

Dear Bob:

It is my pleasure to confirm our offer to you for the position of Vice
President Business Development on behalf of Healthdyne Technologies, Inc.
("Healthdyne Technologies" or "Company"), which employment is to commence on or
about February 15, 1994.

Your initial base salary will be $4,807.69 (gross before deductions) payable on
a bi-weekly basis, which is equivalent to approximately $125,000 per annum.
Future salary adjustments and assignment of job responsibilities shall be based
upon individual and Company performance.  You also will be eligible to
participate in any applicable Company bonus program with a base bonus amount
equal to twenty-five percent (25%) of the base salary paid to you in accordance
with the terms of such program in effect from time to time.

As an incentive to enter into the employment of Healthdyne Technologies, the
Company also agrees to pay you a bonus in the amount of $15,000 (gross before
deductions).  This payment will be made to you within thirty (30) days
following the commencement of your employment with the Company.

This offer of employment also includes a commitment from the Company to
guarantee to you an additional bonus in the amount of $10,000 (gross before
deductions).  This amount will be paid to you upon the completion of your
relocation from Lafayette, California to the Marietta, Georgia area, and is
conditioned on your status as an active employee on the date of payment.

You will be eligible to participate in the customary benefits offered to other
employees in similar positions the first pay period following thirty (30) days
of employment.  A summary of these benefits is enclosed.  More detailed
enrollment information will be sent to you shortly after you begin employment.
If you accept this offer, you may receive copies of Company policies and
procedures in effect from time to time and agree to abide by same, realizing
that changes can occur at any time and that such policies and procedures are
not to be construed as a contract of employment.  You will also be reimbursed
for your reasonable business expenses in accordance with Company policy.

Vacation will accrue at the rate of 1.25 days per month, which is equivalent to
15 days or three (3) weeks per year.



<PAGE>   2

Mr. Robert M. Johnson
January 27, 1994
Page 2



The Company will also reimburse you for your actual expenses incurred in
maintaining your COBRA coverage from your previous employer for a period of
thirty (30) days from your date of hire.  Depending on whether you have elected
individual or family COBRA coverage, the Company will reimburse you up to a
maximum of $126.04 for single coverage and $409.61 for family coverage per
month.

You will be eligible to participate in Healthdyne Technologies Retirement
Benefit Award under the terms and conditions of this plan, with the exception
that you will become twenty-five percent (25%) vested in the plan following
five (5) years of service with the Company, with additional vesting of five
percent (5%) for each year of completed service in excess of five (5) years.

The Company will make a recommendation to the Company's Stock Option Committee
that you be granted a stock option to purchase 10,000 shares of Healthdyne
Technologies Common Stock.  Such stock option will be subject to the standard
terms and conditions of the Company's applicable stock option plan.

In connection with your relocation from your current residence located at 4160
Coralee Lane, Lafayette, California to the Marietta, Georgia area, the
following relocation benefits will be provided to you as a condition of your
employment:

-    Reimbursement for expenses associated with movement of household goods,
     storage, appliance servicing, transportation, house hunting trips,
     temporary lodging and living expenses, purchase of new residence, and
     interim house expenses will be in accordance with the Healthdyne
     Relocation Policy (copy enclosed) as described on Pages 1 and through 6 of
     the Policy.

-    You will also be eligible for reimbursement of expenses associated with
     the sale of your current residence in Lafayette, California.  Eligible
     expenses are defined on Page 7 Section II.A.2. (Sale of Former Residence)
     of the Healthdyne Relocation Policy.

-    Tax protection will also be offered for relocation expenses resulting in
     non-deductible taxable income as defined on Page 6 in Section 5. (Tax
     Effects) of the Healthdyne Relocation Policy.

Should you voluntarily elect to leave the employee of Healthdyne Technologies
within the first twenty-four (24) months of employment with the Company, you
will be required to repay to the Company the relocation expenses incurred and
paid on your behalf through the date of your termination of employment.  The
specific amount of relocation expenses to be repaid to the Company will decline
over time in accordance with the following schedule:



<PAGE>   3

Mr. Robert M. Johnson
January 27, 1994
Page 3



<TABLE>
<CAPTION>
       Period of Employment with       Percentage of Relocation Expenses
        Healthdyne Technologies        Payable to Healthdyne Technologies
       <S>                                          <C>
              0 - 12 months                         100%
             13 - 18 months                          50%
             19 - 24 months                          25%
       Greater than 24 months                         0%
</TABLE>

A special severance arrangement is included in this offer of employment.  This
special severance arrangement will become effective and the payments and
benefits, described below, will be provided to you only if your employment with
the Company is terminated by the Company due to the elimination of your job,
through no fault of your own, with no offer of a comparable position within the
Company or Healthdyne, Inc.  This special severance arrangement will not apply
if your employment with the Company is terminated for performance-related
reasons, voluntary resignation, death, disability, retirement, discharge for
cause, lack of a comparable position upon return from a leave of absence, and
change of control of Healthdyne, Inc.

Under this special severance arrangement, if such termination of employment
occurs during the initial twelve (12) months of your employment with the
Company, you are eligible to receive your regular base salary, in effect at the
time of your termination, for a period of six (6) months from the date of your
termination of employment.  If such termination of employment occurs during the
subsequent twelve (12) months of your employment with the Company, the
severance  payments would be made to you for a period of three (3) months from
the date of your termination of employment.  Following the twenty-fourth (24th)
month of your employment, your severance eligibility and amount of severance
pay will be consistent with the terms and conditions of the Company's Severance
Pay Policy in effect at that time.  These severance payments will be made to
you in regular installments consistent with our normal payroll cycle.  Your
existing medical and life insurance benefits will continue at the normal
contribution rate for you and your dependents during the period of severance
pay.

Severance payments will cease prior to the applicable six (6) or three (3)
month periods described above if, during the period of severance pay, you
violate or do not comply with any of the terms and conditions specified in the
Healthdyne Confidentiality Agreement and the Addendum to Healthdyne
Confidentiality Agreement, or you do not cooperate with the Company in taking
all means reasonably possible to insure the rights and interest of the Company
are fully protected and preserved.  In order to receive the severance pay and
benefits described above, you will be required to release the Company from any
and all other claims, demands, or causes of action.  This release must be
executed prior to the receipt of the first severance pay installment.

This offer is contingent upon your signing the Company's Confidentiality
Agreement and the Addendum to the Company's Confidentiality Agreement attached
hereto.  Please indicate your acceptance to the terms stated herein by signing
the acceptance below and returning this letter, along with an executed original
of the attached Agreements to me in the enclosed self-addressed envelope. Please
retain a copy of the fully executed Agreements for your records.



<PAGE>   4

Mr. Robert M. Johnson
January 27, 1994
Page 4



I look forward to your joining Healthdyne Technologies and believe the
relationship will be mutually rewarding.  I am confident these arrangements
will be satisfactory to you and I look forward to receiving your acceptance of
our offer of employment.

Sincerely,

/s/ Craig B. Reynolds

Craig B. Reynolds
President and Chief Executive Officer



                                   ACCEPTANCE

I have read and understand the foregoing which constitutes the complete, entire
and exclusive statement of the agreement between the Company and the
undersigned and supersedes all prior or contemporaneous proposals, promises,
understandings, representations, conditions, oral or written, relating to the
subject matter of this agreement.  I accept employment at will with the Company
subject to the terms and conditions contained herein.


/s/ Robert M. Johnson                            January 29, 1994
---------------------                            ----------------
Robert M. Johnson                                Date






<PAGE>   5


 .

[HEALTHDYNE LOGO]

January 28, 1994

                                                              By Federal Express

Mr. Robert M. Johnson
4160 Coralee Lane
Lafayette, California  94549

Re:  Offer of Employment

Dear Bob:

This correspondence will confirm your conversation with  Craig Reynolds and
serve as an addendum to Craig's letter to you of January 27, 1994.

The offer of employment extended to you on behalf of Healthdyne Technologies
("Company") will be for the position of Senior Vice President Business
Development.

Healthdyne, Inc. will make a recommendation to the Healthdyne, Inc. Stock
Option Committee that you be granted a stock option to purchase 10,000 shares
of Healthdyne, Inc. Common Stock.  Such stock option will be subject to the
standard terms and conditions of the applicable Healthdyne stock option plan.
This is in addition to the recommendation to be made to the Healthdyne
Technologies, Inc. Stock Option Committee that you be granted a stock option to
purchase 10,000 shares of Healthdyne Technologies Common Stock.

Reimbursement of expenses associated with temporary lodging, living expenses
and periodic trips home will be extended for a period of three (3) months.
Should your wife reside with you during this period, her lodging and living
expenses will be reimbursed under the same guidelines as your lodging and
living expenses.

You are eligible for a merit-based salary increase effective on the one-year
anniversary date of your employment with the Company.  This offer of employment
includes a commitment that the amount of salary increase on that date will be
twelve percent (12%) of your base salary.

The reference of "performance related reasons" will be removed from the special
severance arrangement, therefore, the special severance arrangement will not
apply if your employment with the company is terminated for reasons of
voluntary resignation, death, disability, retirement, discharge for cause, lack
of a comparable job upon return from a leave of absence, or change of control
of Healthdyne, Inc.

The amount of severance pay under this special severance arrangement has been
revised as follows:  If such termination of employment occurs during the
initial twelve (12) months of your

---------------------------

              1850 Parkway Place, Marietta, Georgia  30067-8274 -
                      (404) 423-4500 - FAX: (404) 423-8849



<PAGE>   6

Mr. Robert M. Johnson
January 28, 1994
Page Two




employment with the Company, you are eligible to receive your regular base
salary, in effect at the time of your termination, for a period of six (6)
months from the date of your termination of employment.  If such termination of
employment occurs during the thirteenth (13th) through eighteenth (18th) month
of your employment, the severance payments would be made to you for a period of
four (4) months.  If such termination of employment occurs after the eighteenth
(18th) month of your employment with the Company, the severance payments would
be made to you for a period of three (3) months from the date of your
termination of employment.

Bob, I am pleased to offer these additional considerations to you as part of
your offer of employment.  Please indicate your acceptance of these additional
terms stated herein by signing the acceptance below and returning this letter
to me in the enclosed self-addressed envelope.  Please retain a copy of the
fully executed letter for your records.

I look forward to working with you.  Please do not hesitate to contact me at
(404) 423-8192 if I can answer any questions you may have.

Sincerely,


/s/ Thornton A. Kuntz, Jr.

Thornton A. Kuntz, Jr.
Vice President Administration

c.  C. Reynolds


                                   ACCEPTANCE

I have read and understand the foregoing which constitutes the complete, entire
and exclusive statement of the agreement between the Company and the
undersigned and supersedes all prior or contemporaneous proposals, promises,
understandings, representations, conditions, oral or written, relating to the
subject manner of this agreement.  I accept employment at will with the Company
subject to the terms and conditions contained herein.





/s/ Robert M. Johnson                     January 29, 1994
-----------------------------------       ----------------------------
Robert M. Johnson                         Date