<PAGE>
 
                                                                   EXHIBIT 10.18
                                                                   -------------

                        MARQUETTE MEDICAL SYSTEMS, INC.



                      GLOBAL EMPLOYEE STOCK SHARING PLAN



                                  Rev 5/11/98


                                                                  APRIL 11, 1997
<PAGE>
 
       MARQUETTE MEDICAL SYSTEM, INC.
       GLOBAL SUCCESS SHARING PLAN
       -------------------------------------------------------------------------
       
       
                               TABLE OF CONTENTS

<TABLE>        
       <S>         <C>     
       ARTICLE 1   TITLE
      
       ARTICLE 2   DEFINITIONS AND CONSTRUCTION
   
                   Section 2.1    Definitions
   
                   Section 2.2    Construction
     
       ARTICLE 3   PARTICIPATION
       
                   Section 3.1    Participation

                   Section 3.2    Determination of  Eligibility
       
       ARTICLE 4   CONTRIBUTIONS
                  
                   Section 4.1    Calculation of  Contribution

                   Section 4.2    Payment of Contribution

                   Section 4.3    Stock or Cash Payout

                   Section 4.4    Discretion of Company
                  
                   Section 4.5    Purchase of Shares by Custodian
                  
                   Section 4.6    Limitation on Company Contribution
                       
                   Section 4.7    Withholding of Taxes

       ARTICLE 5   CUSTODIAL ACCOUNT
</TABLE> 

                                       i
<PAGE>
 
<TABLE> 
       <S>         <C>            
                   Section 5.1    Custodial Account
  
       ARTICLE 6   PARTICIPANT ACCOUNTS
                
                   Section 6.1    Individual Account
 
                   Section 6.2    Credits of Individual Account   
                                                                      
                   Section 6.3    Plan Year Allocations               
                                                                      
                   Section 6.4    Correction of Error                 
                                                                      
                   Section 6.5    Other Allocations                   
                                                                      
                   Section 6.6    Participant Statement                

       ARTICLE 7   VESTING
                 
                   Section 7.1    Vesting

       ARTICLE 8   DISTRIBUTIONS
       
                   Section 8.1    Circumstances Entitling Participant to    
                                  Distribution                                  
                                                                                
                   Section 8.2    Method and Manner of Distribution             
                                                                                
                   Section 8.3    Account Participant Election                  
                                                                                
                   Section 8.4    Time of Distribution                          
                                                                                
                   Section 8.5    Designation of Beneficiary in the Event of    
                                  Death         

       ARTICLE 9   PARTICIPANTS' STOCKHOLDER RIGHTS
                  
                   Section 9.1    Voting Rights
</TABLE> 

                                      ii
<PAGE>
 
<TABLE> 
       <S>         <C> 
       ARTICLE 10  PARTICIPATION BY OTHER PARTICIPATING EMPLOYEES
            
                   Section 10.1   Continuance by a Successor

       ARTICLE 11  MISCELLANEOUS

                   Section 11.1   Expenses                                 
                                                                               
                   Section 11.2   Non-transferability and Non-assignability    
                                                                               
                   Section 11.3   Employment Non-contractual                   
                                                                               
                   Section 11.4   Limitation of Rights                         
                                                                               
                   Section 11.5   Merger or Consolidation with Another Plan     

       ARTICLE 12  ALTERATION, WITHDRAWAL AND TERMINATION

                   Section 12.1   Amendment

                   Section 12.2   Termination

                   Section 12.3   Effective Date of Termination

                   Section 12.4   Immunity of Corporation, Subsidiary, or
                                   other Fiduciary

                   Section 12.5   Governing Law
</TABLE> 

                                      iii
<PAGE>
 
                                   ARTICLE 1
                                     TITLE

The title of this Plan shall be the "Marquette Medical Systems, Inc. Global
Employee Stock Sharing Plan".

                                   ARTICLE 2
                         DEFINITIONS AND CONSTRUCTION

SECTION 2.1: DEFINITIONS

As used herein, the following words and phrases shall have the following
respective meanings unless the context clearly indicates otherwise.

(1)  Allocation Date - The date on which the  Company will calculate and
     ---------------                                                    
     allocate to the account of each of the Participants, the Participant's
     share of the Contribution for each Plan Year as determined under Sections
     4.2 and 4.3, which date shall not be more than 60 days after the end of
     each Plan Year.

(2)  Beneficiary/Beneficiaries - The person or persons, who may be so
     -------------------------

(3)  Board or Board of Directors - The Board of Directors of  the Company.
     ---------------------------                                

(4)  Company - Marquette Medical Systems, Inc., a Wisconsin Corporation.
     -------                                                             
     Wherever reference is made in this Plan to the "Company" in the context of
     financial performance, the "Company" shall mean Marquette Medical Systems,
     Inc. and all of its Controlled Subsidiaries that are included on its
     consolidated financial statements.

                                       1
<PAGE>
 
(5)  Contribution - The contribution determined by the Board of Directors
     ------------                                                        
     under Section 4.1 for each Plan Year, on the Determination Date based on
     the performance targets or success sharing targets established for each
     Plan Year. Such performance targets shall consist of one or any combination
     of two or more of revenue; revenue per employee; earnings before income tax
     (profit before taxes); earnings before interest and income tax; net
     earnings (profits after tax); earnings per employee; tangible, controllable
     or total asset turnover; earnings per share; operating income; total
     shareholder return; market share; return on equity; before- or after-tax
     return on net assets; distribution expense; inventory turnover; or economic
     value added; and any such targets may relate to one or any combination of
     two or more of corporate, group, unit, division, or affiliate performance.
     The Board of Directors may at its discretion determine that the
     Contribution for a given year is zero.

(6)  Controlled Subsidiary - A corporation or like entity more than one-half 
     ---------------------                                             
     (1/2) of whose voting power is held by the Company.

(7)  Custodial Account  - All money and property of every kind from time to time
     -----------------                                                  
     held by the Custodian pursuant to the Custodial Account Agreement and the
     Plan, any accumulations of income pursuant thereto and property from time
     to time representing the same.

(8)  Custodian - The Original Custodian [Royal Bank of Canada (Jersey), Ltd.] or
     ---------                                                         
     Successor Custodian of the Custodian Account.

                                       2
<PAGE>
 
(9)  Determination Date - The date on which the Company shall determine and
     ------------------                                                
     announce the Contribution for each Plan Year under Section 4.1, which date
     shall not be more than 60 days after the end of each Plan Year.

(10) Effective Date - The Effective Date of this Plan is May 1, 1997 with the 
     --------------                                                      
     first Plan Year beginning on May 1, 1997 and ending on April 30, 1998 and
     the first payouts being determined under Sections 4.2 and 4.3 on the
     Allocation Date in the calendar year 1998.

(11) Employee - An individual whose relationship with the Company or a 
     --------                                                         
     Controlled Subsidiary is, under the laws of the relevant jurisdiction, that
     of an employee except for:

     (a)  employees who have been hired on a temporary contract to meet a
     a temporary work need with no expectation that they will become permanent
     employees.

     (b)  employees provided by an employment agency to meet temporary staffing
          requirements resulting from temporary peak workloads, sickness or
          medical leave.

(12) Participant - An Employee who as of the end of any Plan Year has been
     -----------                                                     
     continually employed by the Company or a Controlled Subsidiary for more
     than one year. In no event, however, will an Employee who is a member of a
     collective bargaining unit be a Participant unless the collective
     bargaining unit agreement so provides.

(13) Permanent Disability - The mental or physical incapacity of a Participant
     --------------------                                         
     which, in the opinion of a licensed physician approved by the Board of
     Directors or its designee as

                                       3
<PAGE>
 
     evidenced by a certificate issued by such physician, is reasonably certain
     to continue during the remainder of the Participant's lifetime.

(14) Plan - The Plan herein set forth, as amended from time to time.
     ----                                                           

(15) Plan Year - The Plan Year shall each be the fiscal year, running from 
     ---------                                                       
     from May 1 through April 30, with respect to which the Contribution is
     determined by the Company on the Determination Date. The first Year or Plan
     Year will be May 1, 1997 through April 30, 1998.

(16) Profit Sharing Plan - The Marquette Medical Systems, Inc. Profit Sharing
     -------------------
     and 401(k) Plan.

(17) Retires/Retire/Retirement/Retirement Date - means the date on which the
     -----------------------------------------                          
     Participant retires from the employ of the Company or a Controlled
     Subsidiary. The date of retirement will be the date in effect for any given
     jurisdiction as determined by the employee's employer.

(18) Shares - The common shares, 10c par value, of the Company.
     ------                                                    

                                       4
<PAGE>
 
SECTION 2.2: CONSTRUCTION

Whenever used in the Plan, words in the masculine gender shall be deemed to
include masculine, feminine and neuter genders, and, unless the context
otherwise requires, words in the singular shall include the plural and words in
the plural shall include the singular.

                                       5
<PAGE>
 
                                   ARTICLE 3

                                 PARTICIPATION

SECTION 3.1: PARTICIPATION

All Participants, employed by the Company or a Controlled Subsidiary as of the
end of the Plan Year, shall participate under the Plan for such year.

SECTION 3.2: DETERMINATION OF ELIGIBILITY

The Company shall determine the eligibility of each Employee for participation
in the Plan. Such determination shall be conclusive and binding upon all
persons.

                                       6
<PAGE>
 
                                   ARTICLE 4
                                 CONTRIBUTIONS

SECTION 4.1: CALCULATION OF CONTRIBUTION

Subject to Section 4.4, on each Determination Date the Board of Directors of the
Company shall determine the Contribution for the preceding Plan Year based on
the performance measure for that year. Subject to Section 4.4, the Company will,
as soon as possible thereafter, but in no event later than the Allocation Date,
allocate the Contribution for the Plan Year in respect of each Participant by
dividing such Contribution by the number of Participants.

SECTION 4.2: PAYMENT OF CONTRIBUTION

Subject to Section 4.4, the Company shall pay to the Custodian Account and to
the Profit Sharing Plan, as soon as practicable, but in no event later than the
last business day in July immediately following the close of the Plan Year, the
Contribution determined under Section 4.1. The portion of the Contribution
payable to the Custodian will be a fraction, the numerator of which shall be the
number of Participants who are not eligible to participate in the Profit Sharing
Plan and the denominator of which shall be the total number of Participants. The
remainder of the Contribution shall be paid to the Profit Sharing Plan and shall
be held, maintained, and distributed in accordance with the terms of that plan.

                                       7
<PAGE>
 
SECTION 4.3: STOCK OR CASH PAYOUT

Subject to Section 4.4, the Company shall as soon as practicable, but in no
event later than the last business day in July of each year following the end of
the Plan Year, cause the Custodian to pay from the Custodial Account to the
Participants or to the Beneficiary or Beneficiaries of the Participants who have
died, retired, or terminated their employment with the Company or a Controlled
Subsidiary, the amount credited to their respective accounts in cash or Shares,
as the Participant may elect in writing and, in the absence of such election, in
cash.

SECTION 4.4: DISCRETION OF COMPANY

Nothing in Sections 4.1, 4.2 or 4.3 shall be deemed to constitute an implied or
express promise or commitment to make any Contribution hereunder in a Plan Year
in which the performance target is not met, or if Board of Directors decides to
refrain from making any Contribution for that Plan Year.

SECTION 4.5: PURCHASE OF SHARES BY CUSTODIAN

To the extent a Contribution is made in cash, the Shares will be purchased by
the Custodian pursuant to the directions of the Company as soon as practicable
but in no event later than one month following the receipt of the Contribution.

SECTION 4.6: LIMITATION ON COMPANY CONTRIBUTION

Any excess Contribution made by the Company by reason of a good faith mistake of
fact, shall, upon the request of the Company, be returned by the Custodian. The
Company's request and the return of any such Contribution must be made within
one year after such Contribution was

                                       8
<PAGE>
 
mistakenly made. The amount to be returned to the Company pursuant to this
paragraph shall, subject to adjustment for both the movements in the market
value of the Shares and for dividends payable, be the excess of:

(a)  the amount contributed, over

(b)  the amount that would have been contributed had there not been a mistake of
     fact.

SECTION 4.7: WITHHOLDING OF TAXES

The Company may withhold, from any payment which it makes under the Plan, such
sum as the Company may reasonably estimate is necessary to cover any taxes
(whether or not enforceable against the Participant's employer) for which the
Company or a Controlled Subsidiary may be liable, which are, or may be, assessed
with regard to such payment.

                                       9
<PAGE>
 
                                   ARTICLE 5
                               CUSTODIAL ACCOUNT

SECTION 5.1: CUSTODIAL ACCOUNT

The Global Employee Stock Sharing Plan Custodial Account is created by an
agreement between the Company and the Original Custodian and to which this Plan
is a schedule. All Contributions under Section 4.2 , other than those to be made
to the Profit Sharing plan, shall be remitted to the Custodial Account. The
Custodian shall hold all monies and other property received by it and at its
discretion invest and reinvest the same, together with the income therefrom, on
behalf of the Participants not eligible to participate in the Profit Sharing
Plan collectively for the purposes of purchasing Shares or paying expenses of
administration of the Plan and the Custodial Account, to the extent not paid by
the Company, in accordance with the provisions of the Custodial Account
Agreement. The Custodian may with the approval of the Company keep such amount
in cash as may be required for the effective administration and recordkeeping
under the Plan.

                                       10
<PAGE>
 
                                   ARTICLE 6
                             PARTICIPANT ACCOUNTS

SECTION 6.1: INDIVIDUAL ACCOUNT

The Custodian shall establish and maintain, or cause such agent as the Custodian
may select with the approval of the Company, to establish and maintain, a
separate account for each Participant on whose behalf any portion of a
Contribution is paid to the Custodian, which shall be called an "Individual
Account." Such Individual Account shall be solely for accounting purposes and
there shall be no segregation of assets of the Custodial Account among the
separate Individual Accounts, nor will an Account Participant obtain any
equitable or legal interest in any particular Shares or other property until
those Shares or other property vest in accordance with the provisions of this
Plan.

SECTION 6.2: CREDITS TO INDIVIDUAL ACCOUNT

The Custodian shall direct the recordkeeper for the Plan, appointed by the
Custodian with the approval of the Company, to cause the Individual Account of
each Account Participant to be credited with the amount determined pursuant to
Section 4.1 to be allocated to his Individual Account for each Plan Year for
which a Contribution is made and to record all investments in Shares made from
each Individual Account.

SECTION 6.3: PLAN YEAR ALLOCATIONS

Within each Individual Account maintained for an Account Participant there shall
be recorded separately for each Plan Year the total number of Shares allocated
for that Plan Year, which are

                                       11
<PAGE>
 
collectively known as "Plan Year Allocations". For purposes of Sections 7 and 8
each Plan Year Allocations shall be treated as if separate accounts are
maintained for each Plan Year.

SECTION 6.4: CORRECTION OF ERROR

If it shall come to the attention of the Custodian that an error has been made
in any of the allocations prescribed by this Article 6, appropriate adjustment
shall be made to the Individual Accounts of all Account Participants which are
affected by such error, except that no adjustment need be made with respect to
any Account Participant (or Beneficiary) whose Individual Account has been
distributed in full prior to the discovery of such error.

SECTION 6.5: OTHER ALLOCATIONS

Any Shares received by the Custodian as a result of a stock dividend, stock
split, recapitalization or other corporate reorganization of the Company shall
be allocated to the Individual Account and the Plan Year Allocation, as of the
day on which such Shares are received by the Custodian in the same manner as the
Shares to which they are attributable were allocated.

SECTION 6.6: PARTICIPANT STATEMENT

Each Account Participant shall be furnished with a statement as soon as
practicable after the end of each Plan Year, setting forth, as of the end of
such Plan Year, the value of and number of Shares credited to each Account
Participant's Individual Account and Plan Year Allocations.

                                       12
<PAGE>
 
                                   ARTICLE 7
                                    VESTING

SECTION 7.1:   VESTING

(a)       Each Plan Year Allocation shall vest separately in the Account
          Participant absolutely, on the fifth anniversary of the close of the
          Plan Year for which the Contribution is made to the Custodian under
          Section 4.2.

(b)       In the event of the earlier death or termination of employment, of the
          Account Participant, the Account Participant's Individual Account
          shall then absolutely vest in the Participant.

                                       13
<PAGE>
 
                                   ARTICLE 8
                                 DISTRIBUTIONS

SECTION 8.1:   CIRCUMSTANCES ENTITLING ACCOUNT PARTICIPANT TO DISTRIBUTION

An Account Participant (or his Beneficiary) shall be entitled to receive the
distributions of the Plan Year Allocations or the Individual Account, as the
case may be, upon vesting, within the time prescribed under Section 8.4.

SECTION 8.2:   METHOD AND MANNER OF DISTRIBUTION

An Account Participant's Individual Account or the Plan Year Allocations, which
have vested in the Account Participant as provided in Section 7.1, as the case
may be, shall be distributed by the Custodian, in the following manner:

(a)   The Account Participant shall have the right to elect within the time
      provided in Section 8.3 to receive the distribution in cash, or to receive
      Shares.

(b)   If the Account Participant fails to communicate his election as provided
      in Section 8.3, the Custodian will sell the Shares and distribute cash to
      the Account Participant.

(c)   If the total value of the Plan Year Allocations, or the Account
      Participant's Individual Account, as the case may be, is $500 or less, all
      distributions will be made in cash.

The Custodian's obligation to sell and deliver the Shares under the Plan is
subject to the approval of any government authority, required in connection with
the authorization, issuance or sale of such Shares, whether in the United States
of America or in any other country.

                                       14
<PAGE>
 
SECTION 8.3:  ACCOUNT PARTICIPANT ELECTION

Except in the case where the Account Participant's employment with the Company
or Controlled Subsidiary is terminated, the election under Section 8.2 must be
made and communicated to the Custodian within one month prior to the Account
Participant vesting in the Plan Year Allocation. In the event the Account
Participant's employment is terminated, the election must be made and
communicated to the Custodian within 30 days following the date of the
termination of employment.


SECTION 8.4:  TIME OF DISTRIBUTION

The Custodian shall commence distribution of an Account Participant's or former
Account Participant's Plan Year Allocation as soon as practicable after the same
are vested.

SECTION 8.5:  DESIGNATION OF BENEFICIARY IN THE EVENT OF DEATH

Each Account Participant shall have the right to designate a Beneficiary or
Beneficiaries, to receive any distribution to be made under this Article 8, upon
the death of such Account Participant or, in the case of an Account Participant
who dies subsequent to the date in which he becomes entitled to receive a
distribution but prior to the distribution of the entire amount to which he is
entitled under the Plan, any undistributed balance to which such Account
Participant would have been entitled.

In the event of the death of the Account Participant, the Account Participant's
Individual Account shall be held in the Custodial Account for his Beneficiary or
Beneficiaries absolutely and distributed by the Custodian to such Beneficiary or
Beneficiaries in such portion as the Account

                                       15
<PAGE>
 
Participant may by notice in writing to the Custodian or his employer designate
from time to time during his lifetime and in default of such designation in
equal portions. If no Beneficiary or Beneficiaries has been named by a deceased
Account Participant, or the designated Beneficiary or Beneficiaries has
predeceased the Account Participant, or if there is for any other reason a
balance of the deceased Account Participant's Individual Account remaining such
balance shall be held by the Custodian absolutely for:

(a)   the surviving spouse of such deceased Account Participant, if any,
      or

(b)   if there shall be no surviving spouse, for the surviving children of such
      deceased Account Participant, if any, in equal portions, or

(c)   if there shall be no surviving spouse or surviving child, and subject to
      (d) below for the estate of such deceased Account Participant, or

(d)   if no executor or administrator shall have been appointed for the estate
      of such deceased Account Participant within six months following the date
      of the Account Participant's death, in equal portions for the person or
      persons who would be entitled under the intestate succession laws of the
      state or county of the Account Participant's domicile to receive the
      Account Participant's personal estate.

                                       16
<PAGE>
 
                                   ARTICLE 9
                   ACCOUNT PARTICIPANTS' STOCKHOLDER RIGHTS

SECTION 9.1:   VOTING RIGHTS

The Account Participant shall have no right with respect to voting of the Shares
in his Individual Account, except after the Account Participant is vested.



                                   ARTICLE 10
                                   SUCCESSORS

SECTION 10.1:   CONTINUANCE BY A SUCCESSOR

In the event that the Company shall be reorganized by way of merger,
consolidation, transfer of assets or otherwise, so that another corporation
other than the Company shall succeed to all or a portion of such Company's
business, such successor may be substituted for such Company under the Plan by
adopting the Plan.

                                       17
<PAGE>
 
                                  ARTICLE 11
                                 MISCELLANEOUS

SECTION 11.1:   EXPENSES

The Custodian is authorized and directed to pay from the Custodial Account, all
costs and expenses incurred in administering the Plan, including the fees of
counsel, fees of any agents for the Custodian, the fees and expenses of the
Custodian, recordkeeper, and other administrative expenses to the extent such
expenses are not paid by the Company and to charge the Individual Accounts of
the Account Participants.

SECTION 11.2:   NON-TRANSFERABILITY AND NON-ASSIGNABILITY

It is a condition of the Plan, and all rights of each Account Participant (and
Beneficiary) shall be subject thereto, that no right or interest of any Account
Participant (or Beneficiary) in the Plan shall be assignable or transferable in
whole or in part, either directly, by operation of law or otherwise, including,
but not limited to, execution, levy, garnishment, attachment, pledge or
bankruptcy, but excluding devolution by death or mental incompetency, and no
right or interest of any Account Participant (or Beneficiary) in the Plan shall
be liable for, or subject to, any obligation or liability of such Account
Participant (or Beneficiary), including, without prejudice to the generality of
the foregoing, claims for alimony or the support of any spouse.

SECTION 11.3:   EMPLOYMENT NON-CONTRACTUAL

The adoption and maintenance of the Plan shall not be deemed to constitute a
contract between the Company and any Participant to continue the Plan. The Plan
confers no right upon any Employee to continue in the employment with the
Company or the Controlled Subsidiaries.

                                       18
<PAGE>
 
SECTION 11.4:   LIMITATION OF RIGHTS

An Account Participant (or Beneficiary) shall have no right (legal or
equitable), title or claim in or to any specific asset of the Custodial Account,
but shall have the right only to distributions from the Custodial Account on the
terms and conditions herein provided.

SECTION 11.5:   MERGER OR CONSOLIDATION WITH ANOTHER PLAN

If the Plan shall merge or consolidate with, or transfer its assets held by the
Custodian to, any other plan, each Account Participant shall be entitled to
participate in the successor plan immediately after such merger, consolidation,
or transfer upon the terms therein set forth provided that each Participant
shall be vested with benefits that are equal to or greater than the benefit
which he would have been entitled to receive immediately before such merger,
consolidation, or transfer (assuming that the Plan had been terminated) and
participation at such level shall extinguish any rights of the Participant to
receive benefits under this Plan.

                                  ARTICLE 12
                           AMENDMENT AND TERMINATION

SECTION 12.1:   AMENDMENT

The Company may at any time and from time to time amend the Plan by written
instrument duly adopted by the Board of Directors or such committee or delegate
that the Board so empowers, provided, however, that no amendment may be made
which will adversely affect the rights and duties of the Custodian without the
consent of the Custodian or the rights of the Account Participants already
acquired under the Plan.

                                       19
<PAGE>
 
SECTION 12.2:   TERMINATION

The Company may terminate the Plan in its entirety. Such termination shall be
made under a written instrument duly adopted by the Board of Directors. Upon
receipt of a copy of written confirmation of termination or withdrawal as the
case may be, the Custodian shall proceed as follows: In the event of
termination, the Individual Accounts of the Account Participants shall become
fully vested. The Custodian shall determine the portion of the Custodial Account
held by the Custodian which is applicable to each Account Participant or the
Beneficiary and distribute such portion in accordance with Article 8.

SECTION 12.3:   EFFECTIVE DATE OF TERMINATION

The termination of the Plan by the Company shall be effective as of the date
specified in the resolution providing therefore and shall be binding upon all
Participants (and their Beneficiaries), the Custodian and any other parties in
interest.

SECTION 12.4:   IMMUNITY OF CORPORATION, SUBSIDIARY OR OTHER FIDUCIARY

Except as otherwise provided by the law, neither the establishment of the Plan
created hereunder or the Custodial Account nor any modification thereof, nor the
creation of any fund or account or the purchase of distribution of any Shares,
shall be construed as giving to any Participant any legal or equitable right
against the Company, a Controlled Subsidiary or any officer, director, employee
or agent of the Company or a Controlled Subsidiary, or any fiduciary, except as
provided in this Plan.

SECTION 12.5:   GOVERNING LAW

                                       20
<PAGE>
 
The Plan shall be governed by the provisions herein and construed in accordance
with the laws of State of Wisconsin.

                                       21
<PAGE>
 
IN WITNESS WHEREOF, the Company, to evidence adoption of the Plan, has caused
this instrument to be signed and its corporate seal hereto affixed by its
authorized officers, all on this _______ day of __________________, 1997.

MARQUETTE MEDICAL SYSTEMS, INC.

By:    ______________________________________

Name:  ______________________________________

Title: ______________________________________

ATTEST:

By:    ______________________________________

Name:  ______________________________________

Title: ______________________________________

                                       22
<PAGE>
 
                                  ADDENDUM I

  THE TERMS FOR THE OPERATION OF THE PLAN IN RELATION TO THE PARTICIPANTS IN
                                   AUSTRALIA

These terms are made under the Marquette Medical Systems Global Employee
Performance Plan. All the provisions of the Plan apply to the Participants of
the Participating Employer resident in Australia, except to the extent modified
under this Addendum.

The following modifications are made:

1.   SECTION 2.1(8) IS MODIFIED TO READ AS FOLLOWS:

       "(8)

Effective Date - The Effective Date of this Plan will be May 1, 1998 with the
--------------
first Plan Year beginning on May 1, 1998 and ending on April 30, 1999 and the
first payout being determined under Sections 4.2 and 4.3 on the Allocation Date
in the calendar year 1998."

                                       23