APPARATUS FOR AUTOMATICALLY PERIODICALLY MEASURING AND DISPLAYING THE TOTAL AIR EXPIRED BY A SUBJECT DURING EACH OF A SUCCESSION OF GIVEN TIME INTERVALS

• US 3,818,901 A
• Filed: 04/12/1972
• Issued: 06/25/1974
• Est. Priority Date: 04/12/1972
• Status: Expired due to Term

• Current Assignee: Clifford Sanctuary, Donald C. Woods, John A. Bachman
• Original Assignee: Clifford Sanctuary, Donald C. Woods, John A. Bachman
• Inventors: Sanctuary, Clifford, Woods, Donald C., Bachman, John A.
• Primary Examiner(s): Howell, Kyle L.
• Application Number:
  US05/243,369
• Time in Patent Office: 804 Days
• Field of Search: 128/2.07,2.08 73/421.5R,195
• US Class Current: 600/541
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: A61B 5/093 the gases being exhaled into, or inhaled from, an expansible chamber, e.g. bellows or expansible bag
• CPC Class Codes: G01F 15/0755 involving digital counting
• CPC Class Codes: G06F 7/62 Performing operations exclusively by counting total number of pulses ; Multiplication, division or derived operations using combined denominational and incremental processing by counters, i.e. without column shift G06F7/68 takes precedence

Abstract

A respiratory gas analyzer is provided which measures and then instantly displays the volume of expired air from a subject. The instrument includes a positive displacement flow meter which is enclosed in an oven environment and which is used to measure all air expired from the subject, and this volume, computed at body temperature and ambient pressure, saturated with water vapor (BTPS) is digitally displayed at the end of each minute.

Claims

1. Apparatus for automatically periodically measuring and displaying the total air expired by a subject during each of a succession of given time intervals, said apparatus including:

volume measuring apparatus including metering means for receiving the expired air from the subject, said metering means including a member driven by the expired air at a rate proportional to the volume of the expired air for each of the succession of time intervals, and further including transducer means coupled to said member for generating electrical output pulses having a repetition frequency representative of the volume of air expired by the subject during successive time intervals and under standard temperature comditions;

a volume computer coupled to said volume measuring apparatus and including multiplier circuit means for multiplying each pulse of the electrical output pulses therefrom by a predetermined number and further including divider circuit means for subsequently dividing the pulses from the multiplier circuit by a predetermined number for computing the volume of air expired during each of said time intervals corrected to body temperature conditions, and output circuit means coupled to said divider circuit means for producing electrical output pulse signals representative of said corrected volume; and

electrical display means coupled to said output circuit means of said volume computer and responsive to said electrical output pulse signals for providing a reading of the volume of air expired during each of the successive time intervals at body temperature, ambient pressure, and saturated with water vapor.

2. The apparatus defined in claim 1, and which includes oven means for said volume measuring apparatus so as to maintain the expired air passing through said apparatus at an oven temperature slightly above the normal body temperature of the subject to facilitate the computation by said volume computer.

3. The apparatus defined in claim 2, in which said member in said metering means comprises a disc, and in which said metering means includes means rotatably driving said disc at a rate determined by the volume of expired air during each of said time intervals, said disc having slots at the peripheral edge thereof, and in which said transducer means includes a photoelectric scanner for sensing said slots to produce said electric pulses.

4. The apparatus defined in claim 3, in which said disc has a predetermined number of said slots so as to reflect the volumetric difference between a given amount of expired air at the oven temperature and at a lower standard temperature.

5. The apparatus defined in claim 4, in which said slots have an irregular angular spacing around the disc to compensate for a non-uniform rotation rate of the disc.

6. The apparatus defined in claim 1, in which said output circuit means includes frequency divider means for producing said output pulses at different scale levels for said display means.