RESPIRATION METER HAVING SEVERAL MODES OF OPERATION

• US 3,559,638 A
• Filed: 09/19/1967
• Issued: 02/02/1971
• Est. Priority Date: 09/19/1967
• Status: Expired due to Term

• Current Assignee: James A. Potter
• Original Assignee: James A. Potter
• Inventors: Potter, James A.
• Application Number:
  US04/668,917
• Time in Patent Office: 1,232 Days
• US Class Current: 600/540
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices

Abstract

A respiration meter has the following modes of operation: instantaneous air flowrate; minute volume; cumulative volume; tidal volume; and breathing frequency. A selector switch directs an electrical signal indicative of instantaneous air flow along any of the plurality of electrical paths providing such modes of operation. A patient'"'"''"'"'s is exhaled through a chamber in which it creates a pressure attributable to a restricted orifice, which pressure actuates an elastic diaphragm and an arm of a transducer producing such electrical signal.

Claims

1. In a respiration measuring device for measuring a plurality of characteristics of the respiration of a clinical patient wearing a face mask connected by a breathing tube to the measuring device, the gas stream flowing through said breathing tube being the gas stream to be measured, the combination of:

transducer means comprising a restricted orifice through which flows at least a portion of a gas stream and said flow through said restricted orifice imparts a pressure different from ambient pressure, said transducer means being responsive to the pressure difference between ambient pressure and said gas pressure attributable to said orifice, said transducer means providing an electrical signal indicative of the instantaneous flow rate of said gas stream flowing through said breathing tube;

a plurality of alternative circuit means for translating said electrical signal to provide an amplified measurement of a respiration characteristic, one of said measurements being instantaneous flow rate and other of said measurements being of respiration characteristics other than instantaneous flowrate and including breath volume one of said circuit means comprising capacitors adapted to integrate flow rate measurements into volume measurements;

at least one selector switch controlling the selection of the alternative circuit means translating the electrical signal of the transducer means to provide measurements of each of the plurality of respiratory characteristics; and

indicating means providing a display of the measurement of the selected characteristic of the patient s respiration, said characteristic being the instantaneous flow rate when said selector switch is adjusted to an instantaneous flow rate mode of operation and said characteristic being a volume measurement when said selector switch iS adjusted to a volume mode of operation.

2. The measuring device of claim 1 in which the indicating means comprises a milliammeter, and the breathing tube is flexible and adapted to decrease the transmission of shock, vibration, and mechanical movement from the facemask to the transducer means.

3. The measuring device of claim 1 in which said circuit means includes means for averaging the signal from said transducer, whereby said indicating means measures the flow rate averaged over a significant portion of a minute.

4. The measuring device of claim 1 having:

a reset switch means actuable to adjust the indicating means to zero when desired and at the beginning of each measurement;

at least one integrating capacitor for translating said electrical signal of said transducer into a cumulative volume signal; and

one of said circuit means selectable by said selector switch including means for measuring the cumulative volume of the patient'"'"''"'"'s breath.

5. The measuring device of claim 1 having:

a pulse end detector for detecting an end point in said gas flow;

a conductance pulse generator actuated by the pulses from the pulse end detector;

a conductance pulse assignor means for switching the conductance pulses for discharging any integrating capacitor for translating the instantaneous flow rate signal of the transducer into a signal indicative of the cumulative volume per breath and being discharged automatically at the end of each breath as detected by said end point of said gas flow, whereby the maximum reading of the indicating means during each breath is a measure of the partient'"'"''"'"'s tidal volume.

6. A measuring device in accordance with claim 5 wherein there is:

a timed pulse generator means within the selector switch operative while the selector switch is adjusted to frequency mode of operation for directing said conductance pulses to said timed pulse generator;

switching means directing the output of the timed pulse generator through circuit means in which such output signals are averaged, modified by resistors, and amplified to provide a signal actuating the indicating means to provide a reading indicative of the number of breaths per minute.

7. The measuring device of claim 6 said selector switch includes switching means adapted to permit testing of the measuring device.

8. The measuring device of claim 1 wherein said transducer means includes a shiftable electrical component and a fixed electrical component, said shiftable and fixed electrical components cooperating to control an electrical signal indicative of the position of the shiftable electrical component;

a first chamber, said restricted orifice modifying the flow of at least substantially all of the gas stream in said breathing tube to impart a nonambient pressure in said first chamber;

a zone-type second chamber maintained at substantially ambient pressure;

an elastic diaphragm separating the two chambers, the central portion of said diaphragm being shifted by the changes in pressure in the first chamber attributable to the gas flow through the restricted orifice, said shiftable electrical component being moved by the central portion of the diaphragm to control said signal.

9. The measuring device of claim 1 wherein said alternative circuit means are additionally selectable by said selector switch to measure a low range of averaged volume per unit time, to measure a high range of average volume per unit time, to measure a low range of cumulative volume, to measure a high range of cumulative volume, to measure a low range of volume per breath, to measure a high range of volume per breath, to measure a low range of breaths per unit time, and to measure a high range of breaths per minute;

said alternative circuit means including means for converting the electrical signal from the transducer means for actuating the indicating means in each of the plurality of modes of operation; and

a pair of scales in the indicating means, the higher scale being the square root of 10 multiple oF the lower scale.