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

• Current Assignee: Franz Hampl
• Original Assignee: Franz Hampl
• Inventors: Hampl, Franz
• Primary Examiner(s): Howell, Kyle L.
• Application Number:
  US05/367,344
• Time in Patent Office: 574 Days
• Field of Search: 128/2.07,2.08,2R,DIG.17
• US Class Current: 600/533
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity

Abstract

A flow resistance chamber through which a person breathes has a flow resistance which can be rapidly switched between two values of resistance. The pressure differential across the resistance is measured, and the electrical output of the pressure difference measurement is switched between two storage circuits in synchronism with the switching of the flow resistance. This switching is done for a period that is short compared with the breath cycle. The quotient of the two pressure differences registered in the storage circuits is continuously formed and displayed on an indicator or recording.

Claims

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.

2. A direct indicating device for continuously measuring respiratory resistance as defined in claim 1 in which:

flow direction responsive means are interposed in the signal path between said pressure sensing means and said signal switching means for switching off the signal supplied to said signal switching means during periods of breath flow in one direction of breathing.

3. A direct indicating device for measuring respiratory resistance as defined in claim 1, in which:

a path rectifying means is interposed in the signal path between said pressure sensing means and said signal switching means and is arranged to switch the polarity of the output signal of said pressure sensing means or of a signal derived therefrom, so that the polarity of the output of said quotient producing means will remain the same regardless of direction of respiratory air flow through said flow resistance chamber.

4. A direct indicating device for continuously measuring respiratory resistance as defined in claim 1 in which said storage means includes means for rapid setting of the storage level therein during alternate switchIng intervals of said signal switching means to a new value of said electrical output of said pressure sensing means, in the event of change of such value, and includes means for maintaining the storage level therein substantially constant during the other switching intervals of said signal switching means.

5. A direct indicating device for continuously measuring respiratory resistance as defined in claim 2 in which said storage means includes means for rapid setting of the storage level therein during alternate switching intervals of said signal switching means occurring during periods of breath flow in the direction of breathing for which said flow direction responsive means does not switch off the signal supplied to said signal switching means, such setting of said storage level being then effected to a substantially momentary value of said electrical output of said pressure sensing means, and in which during other switching intervals of said signal switching means, said storage means includes means for maintaining the storage level substantially constant.

6. A direct indicating device for continuously measuring respiratory resistance as defined in claim 2 in which said indicating means is a means for visually recording respiratory resistance as a function of time at least during periods of breath flow in one direction of breathing.

7. A direct indicating device for continuously measuring respiratory resistance as defined in claim 2 in which said indicating means is a means for visually displaying with brief persistance the respiratory resistance of a patient, at least during periods of breath flow in one direction of breathing.