SCHEDULE 14A INFORMATION
 
                  Proxy Statement Pursuant to Section14(a) of
            the Securities Exchange Act of 1934 (Amendment No.    )
 
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    /X/  Definitive Additional Materials
    / /  Soliciting Material Pursuant to Section240.14a-11(c) or
         Section240.14a-12
 
                                HEALTHDYNE TECHNOLOGIES, INC.
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                (Name of Registrant as Specified In Its Charter)
 
                                       INVACARE CORPORATION
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    (Name of Person(s) Filing Proxy Statement, if other than the Registrant)
 
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                             [INVACARE LETTERHEAD]
 
                                                                   June 27, 1997
 
     DON'T BE FOOLED--HEALTHDYNE'S BOARD STILL REFUSES TO SELL THE COMPANY
 
               IT'S TIME TO ELECT A BOARD TO ACT ON YOUR BEHALF.
                        VOTE YOUR GOLD PROXY CARD TODAY!
 
    DEAR FELLOW HEALTHDYNE SHAREHOLDER:
 
    After months of fruitless attempts to get Healthdyne's Board to negotiate a
sale of the company, it is now time for the shareholders -- the real owners of
Healthdyne -- to express their views.
 
    Your task is simple: if you want to elect a board of directors committed to
conducting an auction to sell Healthdyne at the best available price, vote the
enclosed GOLD proxy card to replace the current Healthdyne Board with Invacare's
qualified, independent nominees.
 
    We also seek your vote in favor of Invacare's four corporate governance
proposals. These proposals would further facilitate a sale of Healthdyne if the
shareholders were in favor of such a transaction.
 
                  DECIDE FOR YOURSELF IF THE HEALTHDYNE BOARD
                     HAS BEEN ACTING IN YOUR BEST INTERESTS
 
    Invacare made its original tender offer for Healthdyne on January 27 for a
price of $13 cash per share -- which represented a handsome premium of more than
45% over Healthdyne's $8.88 closing price on December 31, 1996, the day before
Invacare made its initial acquisition proposal to Healthdyne.
 
    SINCE THEN, EVEN THOUGH HEALTHDYNE REFUSED TO CONDUCT ANY DISCUSSIONS OR
NEGOTIATIONS WITH US, WE HAVE INCREASED OUR OFFER TWICE AND NOW OUR $15 PER
SHARE "BEST AND FINAL" OFFER REPRESENTS A PREMIUM OF APPROXIMATELY 70%.
 
    During this time, we have repeatedly invited Healthdyne to enter into
discussions or negotiations with us.

    Unfortunately, our efforts to spur the Healthdyne Board to negotiate with us
on your behalf have been unsuccessful. Instead, the Healthdyne Board has been
busy entrenching itself as deeply as possible:
 
   -   THE HEALTHDYNE BOARD TRIED TO USURP THE RIGHTS OF SHAREHOLDERS OF ALL
       GEORGIA PUBLIC CORPORATIONS THROUGH A "MIDNIGHT RAID" IN THE GEORGIA
       STATE LEGISLATURE. The proposed legislation -- which fortunately did not
       pass -- would have automatically forced the boards of directors of all
       Georgia public corporations to be staggered. If this effort had
       succeeded, it would have eliminated your ability to replace a majority of
       Healthdyne's directors for as much as two years.
 
   -   THE BOARD HAS INSTALLED AND REFUSES TO REMOVE A "DEAD-HAND" PROVISION IN
       ITS "POISON PILL" DEFENSE. The "dead-hand" provision would not allow a
       new Board elected by you to nullify the pill to permit a sale to go
       forward. As described in the enclosed proxy statement, we believe the
       "dead-hand" is illegal and have challenged it in court. Additionally, we
       are asking you to vote FOR a proposal which would require the current
       Board to remove the "dead-hand", although Healthdyne has challenged this
       proposal in court.
 
   -   After more than six months of blatant stonewalling, including delaying
       the Annual Meeting as long as possible, the Board now says, on the eve of
       this proxy contest, that it will "explore alternatives" to our offer and
       "talk to third parties" -- BUT THEY STUBBORNLY MAINTAIN THAT HEALTHDYNE
       IS NOT FOR SALE.
 
   -   Furthermore, they have said they will only be willing to talk with
       Invacare if we drop our tender offer and proxy fight, leaving the
       shareholders with no choice at the Annual Meeting. We of course can not
       accept these outrageous conditions.
 
                  DON'T BE FOOLED! VOTE YOUR GOLD PROXY TODAY.
 
    In light of their stonewalling and disingenuous statements, ask yourself if
you can trust the current Board to sell the company promptly.
 
   -   If the current Board is reelected and fails to sell the company, what
       will happen to the price of your stock? REMEMBER THAT HEALTHDYNE'S STOCK,
       WHICH HAD BEEN TRADING SLIGHTLY ABOVE OUR OFFER PRICE, PLUMMETED TO THE
       $11 RANGE WHEN HEALTHDYNE ALMOST SUCCEEDED IN BLOCKING OUR OFFER IN THE
       GEORGIA LEGISLATURE.
 
   -   As we stated when we raised our offer, if our nominees are not elected,
       we will evaluate our options at that time, including withdrawing our
       offer. ASK YOURSELF WHETHER THE HEALTHDYNE BOARD WILL CONTINUE EVEN TO
       "EXPLORE ALTERNATIVES" IF OUR OFFER GOES AWAY.
 
   -   Finally, don't be distracted by Healthdyne's ridiculous statement that if
       Invacare's nominees win the proxy contest, we might not pursue our offer.
       Why would we waste the time and money on this nearly seven-month takeover
       battle only to walk away after our nominees are elected and our offer can
       finally be considered? It can't be, as they claim, merely to gain
       "control" of Healthdyne -- Invacare does not control these independent
       nominees and, in any case, Invacare wants to acquire Healthdyne, not just
       "control" it.

    THE NOMINEES PROPOSED BY INVACARE ARE AN OUTSTANDING GROUP OF BUSINESS
LEADERS, FIVE OF WHOM SERVE ON THE BOARDS OF PUBLIC COMPANIES. They include
Chairmen of the Board, Presidents and CEOs, and a managing partner of a
well-respected law firm.
 
    Their backgrounds and credentials are listed beginning on page 6 of our
proxy statement. You should take the time to contrast our nominees'
accomplishments to the resumes of Healthdyne's nominees in their proxy
statement.
 
    If elected, our nominees are fully committed to acting as independent
directors in your best interests and conducting a prompt auction and sale of
Healthdyne at the best available price and terms. Of course, we hope that
Invacare is the successful bidder, but the nominees fully intend to promptly
solicit and review all bona fide offers.
 
            IT'S FINALLY TIME FOR THE BOARD'S ENTRENCHMENT GAMES TO
             STOP AND FOR THE SHAREHOLDERS TO DECIDE THE COURSE OF
                              HEALTHDYNE'S FUTURE
 
    Healthdyne's annual meeting is scheduled for July 30. Your vote -- no matter
how many or few shares you own -- is critical. Please take some time to study
the enclosed proxy statement carefully and then execute and mail the enclosed
GOLD proxy card. Please do so today. I hope you will also consider attending the
meeting so that I will have an opportunity to meet you personally.
 
    REPLACING THE HEALTHDYNE BOARD AND APPROVING OUR PROPOSALS MAY BE YOUR ONLY
REAL CHANCE TO HAVE THE OPPORTUNITY TO RECEIVE A SIGNIFICANT PREMIUM FOR YOUR
SHARES NOW.
 
    We appreciate your support of our nominees and our corporate governance
proposals. If you have questions or need assistance in voting your shares,
please contact MacKenzie Partners, Inc., which is assisting us with this
transaction, toll-free at (800) 322-2885.
 
                                      Sincerely,

                                      /s/ A. Malachi Mixon, III

                                      A. MALACHI MIXON, III
                                      CHAIRMAN OF THE BOARD &
                                        CHIEF EXECUTIVE OFFICER

 
If you have any questions or need assistance in completing the GOLD proxy card,
                                please contact:
 
                            MACKENZIE PARTNERS, INC.
 
                                156 Fifth Avenue
                            New York, New York 10010
                         (212) 929-5500 (call collect)
                                       or
                         CALL TOLL-FREE (800) 322-2885