SPIROMETER

• US 3,577,984 A
• Filed: 03/27/1967
• Issued: 05/11/1971
• Est. Priority Date: 03/27/1967
• Status: Expired due to Term

• Current Assignee: Bear Medical Systems Inc. (Becton, Dickinson & Co)
• Original Assignee: Donald Levy, Rusz Tibor
• Inventors: Levy, Donald, RUSZ TIBOR
• Application Number:
  US04/626,240
• Time in Patent Office: 1,506 Days
• US Class Current: 600/538
• CPC Class Codes: A61B 5/087 Measuring breath flow

Abstract

An electronic spirometer is disclosed for measuring a plurality of airflow and air volume parameters of a patient. A resistance measurement bridge having a transducer with a heated platinum wire is used to measure airflow. A detector network detects and stores the peak airflow. A linearizing network and a sequence and storage circuit convert the measured airflow into volume signals during successive intervals of a measurement cycle. A meter circuit is selectively controlled by the peak detector network and the storage circuit as well as the linearizing network and an averaging resistance capacitor arrangement for providing indications of the measured airflow and volumes.

Claims

1. Measuring equipment comprising:

a transducer having an electrical resistance element operating at a prescribed temperature to produce a desired electrical resistance for said element and being responsive to the flow of gas therethrough for altering said temperature to change said resistance of said element, apparatus responsive to the resistances of said element for translating said resistances into output signals representing gas flow, said output signals being nonlinear with respect to said gas flow through said transducer, and means connectable to said apparatus for selectively converting said output signals into signal indications of the magnitude of said gas flow through said transducer and including means altering said signal indications into linear signal indications of the magnitude of gas flow through said transducer.

2. Measuring equipment in accordance with claim 1 wherein said converting means further includes means averaging said linearized signal indications for supplying electrical signals representing minute magnitude of gas flow through said transducer.

3. Equipment for measuring airflow comprising:

a measurement bridge including a transducer having an electrical resistance element, a voltage source applying operating voltages to said bridge and resistance element, said element being heated by the applied voltage to produce a prescribed reference resistance, means controlled by the resistance of said element for regulating the operating voltage applied to said bridge for maintaining a constant applied voltage to said element for heating thereof, said element being responsive to the flow of air through said transducer for altering the prescribed resistance of said element to control said regulating means for changing the applied voltage to said bridge, and apparatus responsive to the voltages applied to said bridge for indicating the magnitude of the airflow through said transducer.

4. Equipment for measuring airflow in accordance with claim 3 wherein said indicating apparatus comprises:

a meter circuit operable for supplying indications of volumes of airflow through said transducer, and a resistance and capacitance arrangement controlled by the voltages applied to said bridge for operating said meter circuit to supply indications of the minute volumes of airflow through said transducer.

5. In combination:

means responsive to airflow within a prescribed time period for producing electrical signals representing the magnitudes of said airflow, control means including means providing a plurality of discrete intervals within said time period and means controlled by said providing means for translating the produced electrical signals into voltages representing the volumes of said airflow within each of said plurality of discrete intervals, and means selectively responsive to each of said voltages for indicating the volume of said airflow within each of said discrete intervals.

6. The combination in accordance with claim 5 wherein said control means further includes:

an electrical network means responsive to the produced electrical signals for storing a voltage corresponding to the peak magnitude of said airflow, and said indicating means being controllable by the stored voltage for indicating said peak magnitude of said airflow.

7. The combination in accordance with claim 5 wherein said control means further includes:

a plurality of storage devices connectable to said translating means for storing individual voltages on each of said devices representing the volume of airflow within one of said discrete intervals, and means operative for controlling the sequential connection of each of said devices to said translating means.

8. The combination in accordance with claim 5 wherein said translating means includes:

an electrical network responsive to the receipt of the produCed airflow electrical signals for supplying output electrical signals having a linear response relationship with respect to said airflow, an amplifier device for integrating the airflow electrical signals to produce the air volume voltages, and said amplifier device is responsive to said output electrical signals for producing said air volume signals.

9. The combination in accordance with claim 5 wherein said producing means comprises a transducer having:

two separable, complementary interfitting and hollow cylindrical bodies, one of said bodies s having and extension element forming a mouthpiece for admitting air to be measured through said one hollow body, the other of said bodies having means defining an exhaust aperture for exhausting air admitted in said hollow other body, a platinum wire resistance, means supporting said wire resistance including a plurality of electrically conductive plates secured to said wire resistance and connectable to said electrical circuit, a pair of hollow cylindrical devices each having an axial bore and being within said other hollow body positioning said supporting means with said wire resistance substantially perpendicular to the path of airflow, said supporting means having means defining an aperture for enabling air admitted into said one hollow body to pass through said other hollow body and said axial bores to said exhaust aperture, a first screen member positioned within said one hollow body about said mouthpiece, and a second screen member positioned within said other hollow body between said exhaust aperture and said supported wire resistance.

10. A spirometer comprising:

a transducer responsive to the receipt of airflow for producing electrical conditions representing the magnitude of said airflow, apparatus responsive to the produced electrical conditions for translating said conditions into output signals corresponding to said airflow magnitudes, a plurality of storage devices connectable to said apparatus for storing said output signals, sequence means sequentially controlling the connection of said devices to said apparatus at prescribed time intervals for storing discrete ones of said output signals on each of said devices, and means selectively connectable to each one of said devices for converting the signal stored on said one device into an indication of the magnitudes of said air volume and said airflow through said transducer during one of said prescribed intervals.

11. A spirometer in accordance with claim 10 wherein:

said transducer comprises an electrical resistance element which is responsive to airflow through said transducer for producing predetermined electrical resistances representing the magnitudes of said airflow, and said apparatus comprises translating means responsive to produced electrical resistances for supplying predetermined output signals corresponding to each of said airflow magnitudes.

12. A spirometer in accordance with claim 11 wherein:

said translating means includes a resistive measurement bridge and said electrical resistance element is connected in said bridge, and a voltage source applying operating voltages to said bridge including said resistive element, said voltage applied to said element effecting a current flow therethrough for heating said element to produce a predetermined electrical resistance, said resistance element thereafter being responsive to said airflow through said transducer for changing the resistance of said element from said predetermined resistance.

13. A spirometer in accordance with claim 12 wherein:

said voltage source includes a voltage regulator responsive to the resistances of said resistance element for applying voltages to said bridge for maintaining a constant applied voltage to said element for said heating thereof.

14. A spirometer in accordance with claim 13 wherein:

said apparatus further includes amplifier means connected to said measurement bridge and being responsive to said applied voltages for supplying said predetermined output signals corresponding to each of said airflow magnitudes.

15. A spirometer in accordance with claim 14 wherein:

said apparatus further comprises a peak detector network responsive to said predetermined output signals from said amplifier means for storing the one of said signals corresponding to the peak airflow through said transducer.

16. A spirometer in accordance with claim 15 wherein:

said peak detector network comprises a series arrangement of a semiconductor device and a capacitor for storing said one output signal from said amplifier means.

17. A spirometer in accordance with claim 14 wherein:

each of said storage devices includes a storage capacitor, and said amplifier means includes and amplifier device connected to said measurement bridge and being responsive to said applied voltages from said voltage regulator for producing prescribed output signals, and an electrical network responsive to said prescribed output signals for supplying said predetermined output signals for storage on each of said capacitors.

18. A spirometer in accordance with claim 17 wherein:

said prescribed output signals from said amplifier device have a nonlinear relationship with respect to airflow through said transducer, and said electrical network includes means for altering said prescribed output signals into network output signals which have a linear relationship with respect to airflow through said transducer.

19. A spirometer in accordance with claim 18 wherein:

said altering electrical network comprises a first diode and a first resistor in series and at least a second diode and a second resistor both connected in parallel with said first resistor and in series with said first diode and said amplifier device.

20. A spirometer in accordance with claim 19 wherein:

said amplifier means further comprises another amplifier device responsive to said network output signals for controlling the storage of said predetermined output signals on each of said storage capacitors corresponding to the volumes of airflow through said transducer.

21. A spirometer in accordance with claim 20 wherein said sequence means includes:

means for producing timing signals each of which corresponds to a prescribed interval during said airflow, a plurality of switching devices connecting said storage capacitors to said other amplifier device for storing said predetermined output signals and being responsive to said timing signals for successively disconnecting each of said capacitors from said other amplifier device.

22. A spirometer in accordance with claim 21 wherein:

said timing signal producing means comprises means for generating a series of pulses each of which corresponds to an individual prescribed interval during said airflow through said transducer, and each of said switching devices comprises a relay having contacts connecting one of said storage capacitors to said other amplifier device and being responsive to a predetermined one of said pulses from said pulse generator for operating its contacts to disconnect said one storage capacitor from said other amplifier device.

23. A spirometer in accordance with claim 22 wherein:

said converting means includes a meter circuit selectively connected to said storage capacitors for converting the signals stored on each of said capacitors into indications of the volumes of airflow through said transducer during each of said prescribed intervals.

24. A spirometer in accordance with claim 23 wherein said meter circuit comprises:

a meter and transistor circuitry selectively connectable to each of said storage capacitors and being responsive to the signals stored on each of said capacitors for operating said meter to indicate said airflows and volumes through said transducer during said prescribed intervals, and further including a selector switch controllable foR connecting each of said capacitors individually to said transistor circuitry.

25. In combination:

means including a linearizing electrical network responsive to the flow of fluid for producing linear electrical signals with respect to said flow, and an electrical network arrangement comprising resistor-capacitor means averaging said linear electrical signals for translation into electrical indications of said minute magnitude of said flow.

26. The combination in accordance with claim 25 wherein field-effect transistor circuitry and meter means cooperate for said translation of the averaged linear electrical signals into electrical meter indications of the minute volume of said flow.

27. In combination:

means responsive to the flow of fluid within a prescribed time period for producing electrical signals representing said flow, and means automatically translating said signals into electrical indications of the volume of said fluid flow with said prescribed time period, said translating means including;

an electrical linearizing network for converting said electrical signals into linear output signals with respect to flow, and integrator means responsive to said output signals for deriving volume signal indications within said time period.

28. The combination in accordance with claim 27 wherein said translating means further includes:

means for storing said volume signal indications, and transistor and meter means responsive to the stored volume signal indications for translating said indications into meter indications of volume.

29. Equipment for measuring fluid flow magnitude per minute comprising:

means responsive to the flow of fluid for producing electrical signals representing said flow, a linearizing electrical network for translating said electrical signals into linear output signals with respect to said flow, an averaging electrical network for averaging said linear output signals into electrical signal indications of the flow magnitude per minute, and means cooperating with said averaging electrical network for translating said last mentioned electrical signals into a display of said flow magnitude per minute.