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DIRECT INDICATING DEVICES FOR MEASURING RESPIRATORY RESISTANCE

  • US 3,857,385 A
  • Filed: 06/05/1973
  • Issued: 12/31/1974
  • Est. Priority Date: 04/03/1970
  • Status: Expired due to Term
First Claim
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1. A direct indicating device for continuously measuring the internal resistance of a person'"'"''"'"'s respiratory system comprising:

  • a flow resistance chamber having a connection adapted for the person'"'"''"'"'s mouth or nose and a connection to the atmosphere and having an interposed variable resistance means, switchable between two finite values of resistance, through which air breathed by said person through said mouth or nose connection must pass;

    flow resistance switching means operatively connected with said variable resistance means for switching said resistance means between said two values of resistance;

    pressure sensing means connected to said chamber and responsive to the pressure difference across said flow resistance means and including means for providing an electrical output representative of said pressure difference;

    two electrical storage means for storing differential pressure output signals of said pressure sensing means respectively related to said two resistance values, each of said storage means having an input and an output connection and includes means capable of following a signal provided to said input connection and of storing the last value of the signal so provided when said input connection is disconnected from said pressure sensing means;

    signal switching means synchronized with said flow resistance switching means arranged for alternately connecting each of said storage means to said electrical output of said pressure sensing means;

    timing means including means for causing repetitive back-andforth operation, in synchronism, of said flow resistance switching means and for said signal switching means at intervals short compared with a person'"'"''"'"'s normal breathing cycle;

    quotient producing means responsive to the respective signals present in said two storage means, and indicating means responsive to said quotient producing means for continuously indicating respiratory resistance of said person during at least one direction of breathing, said indicating means being capable of and arranged for responding to variations of the output of said quotient producing means within any unidirectional breath flow period of the person'"'"''"'"'s breathing cycle.

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