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Expiration valve control arrangement for a ventilating apparatus

  • US 5,065,746 A
  • Filed: 06/30/1989
  • Issued: 11/19/1991
  • Est. Priority Date: 07/07/1988
  • Status: Expired due to Fees
First Claim
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1. An expiration valve control arrangement for a ventilating apparatus having an expiration branch line, said expiration branch line producing dynamic flow resistance as the exhaled breathing gas flows therethrough, said dynamic flow resistance producing dynamic positive end expiratory pressure in the expiration branch line, the arrangement comprising:

  • an expiration valve having an expiration valve housing and membrane valve means for partitioning said housing into a control chamber and a valve chamber;

    an inlet for admitting exhaled breathing gas into said valve chamber;

    said membrane valve means being movable so as to close said inlet during inspiration and open said inlet during expiration so as to cause said inlet to communicate with said valve chamber;

    means for compensating for said dynamic positive end expiratory pressure comprising;

    control valve for generating a control pressure for maintaining a desired end expiratory pressure during expiration in said control chamber of said expiration valve, said control valve including a control valve housing and a plate membrane for partitioning said control valve housing into first and second chambers;

    control gas supply means for supplying a control gas under pressure;

    feed means for conducting said control gas into said control valve;

    said control valve including valve seat means disposed in said first chamber and communicating with said feed means;

    said plate membrane being mounted in said control valve housing for coacting with said valve seat means for opening and closing said valve seat means to said first chamber;

    said feed means including throttle means disposed between said supply means and said valve seat means for throttling the flow of said control gasa conduit connecting said throttle means to said control chamber of said expiration valve for transmitting said control gas to said control chamber;

    underpressure means for generating an underpressure in said valve chamber of said expiration valve corresponding to said dynamic positive end expiratory pressure; and

    ,said control valve further including force applying means for applying a first force to said plate membrane during said inspiration for closing said valve seat means to said first chamber thereby causing the control gas flowing from said throttle means to produce an overpressure in said control chamber causing said membrane valve means of said expiration valve to close and for applying a second force to said control membrane during said expiration for opening said valve seat means to said first chamber, and said force applying means coating with said throttle means to adjust said desired end expiratory pressure in said control chamber causing said membrane valve means to open and permit exhalation, said second force being less than said first force and being adjustable to set said desired end expiratory pressure in said control chamber to compensate for said dynamic positive end expiratory pressure in the expiration branch line.

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