CPAP pressure and flow transducer

• US 6,135,106 A
• Filed: 08/22/1997
• Issued: 10/24/2000
• Est. Priority Date: 08/22/1997
• Status: Expired due to Term

• Current Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Inventors: Waldo, Jeffrey M., Dirks, Aaron J.
• Primary Examiner(s): Weiss, John G.
• Assistant Examiner(s): SRIVASTAVA, VIRENDRA KUMAR
• Application Number:
  US08/916,879
• Time in Patent Office: 1,159 Days
• Field of Search: 128/204.23, 128/204.18, 128/204.21, 128/204.22, 128/205.23, 128/207.14, 128/203.12, 128/203.15, 60/520, 60/532, 73/861.74, 73/861.52, 600/538
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/0858 Pressure sampling ports
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter

Abstract

A continuous positive airway pressure (CPAP) apparatus for treatment of sleep apnea stores data indicating patient compliance with the prescribed mode of use. The apparatus includes a tubular probe positioned transversely in the conduit between the blower and nose mask. The probe tip is configured for creating a varying pressure across in the probe in response to varying air flow thereacross indicative of patient respiration. A pressure sensor connected to the probe produces signals representative of the varying air pressure. Compliance data, derived from the pressure sensor signals and representative of the patient'"'"'s use of the apparatus, are stored for subsequent analysis.

Claims

1. In a positive airway pressure apparatus including a gas delivery unit operable to deliver pressurized gas to a patient'"'"'s airway during successive patient breath cycles, a sensor operably connected with said unit and a controller coupled with said sensor, the improvement which comprises:

said sensor operable to measure a patient breath-indicating parameter selected from the group consisting of pressure, air flow direction and combinations thereof in said unit and to generate a sensor output corresponding to said parameter;

said output presenting high and low peaks during a breath; and

said controller receiving said sensor output for analyzing the output to determine use or non-use of the apparatus by the patient as a function of said measured parameter and operable for analyzing said peaks and comparing said peaks to peak data representative of previous breaths of the patient for determining whether current high and low peaks are representative of an actual breath.

2. The apparatus of claim 1, said gas delivery unit including a blower unit, a nose mask configured for covering the nose of the patient, and a conduit interconnecting said blower unit with said nose mask, said blower unit delivering pressurized gas through said conduit, to said nose mask and thereby to the patient.

3. The apparatus of claim 2, further including a signal processor coupled with said sensor operable for receiving and analyzing said patient breath-indicating parameter for determining said air flow direction in said conduit, such being indicative of the patient'"'"'s respiration and thereby the patient'"'"'s use of said apparatus.

4. The apparatus of claim 3, said signal processor including a microcontroller operable for analyzing said signals to determine air flow magnitudes in said conduit and whether said magnitudes exceed predetermined limits in correspondence with said air flow direction, such being indicative of the patient'"'"'s respiration and thereby the patient'"'"'s use of said apparatus.

5. The apparatus of claim 4, said output presenting high and low peaks during a breath, said microcontroller operable for analyzing said peaks and comparing said peaks to peak data representative of previous breaths of the patient for determining whether current high and low peaks are representative of an actual breath.

6. The apparatus of claim 5, said peak data including the average of a previous plurality of detected breaths, said microcontroller operable for determining whether the peak-to-peak difference of a current breath exceeds a predetermined threshold of the average peak-to-peak difference of a plurality of previous breaths.

7. The apparatus of claim 6, said plurality of detected breaths including eight previously detected breaths, said threshold including 40%.

8. The apparatus of claim 1, said controller including a memory unit operable for storing said output and for subsequent retrieval thereof.

9. The apparatus of claim 8, said opposed probe end operatively coupled with said sensor and operable for sensing said varying pressure and for producing pressure signals representative thereof.

10. The apparatus of claim 12, said peak data including the average of a previous plurality of detected breaths, said controller operable for determining whether the peak-to-peak difference of a current breath exceeds a pre-determined threshold of the average peak-to-peak difference of a plurality of previous breaths.

11. The apparatus of claim 10, said plurality of detected breaths including eight previous detected breaths, said threshold including 40%.

12. The apparatus of claim 1, said output including the times during which said apparatus was used.

13. The apparatus of claim 1, said output including waveforms having peaks representative of a patient breath-indicating parameter and thereby representative of patient respiration.

14. The apparatus of claim 13, said controller including a computer program operable for directing said controller and analyzing said waveform.

15. The apparatus of claim 1, said output producing an analog air pressure signal corresponding to said patient breath-indicating parameter.

16. In a positive airway pressure apparatus including a gas delivery unit operable to deliver pressurized gas to a patient'"'"'s airway during successive patient breath cycles, a sensor operably connected with said unit and a controller coupled with said sensor, the improvement which comprises:

said sensor operable to measure a patient breath-indicating parameter selected from the group consisting of pressure, air flow direction and combinations thereof in said unit and to generate a sensor output corresponding to said parameter;

said controller receiving said sensor output for analyzing the output to determine use or non-use of the apparatus by the patient as a function of said measured parameter;

said output including waveforms having peaks representative of a patient breath-indicating parameter and thereby representative of patient respiration;

said controller including a computer program operable for directing said controller and analyzing said waveform; and

said program including high and low peak detect for said waveforms and operable for analyzing peak-to-peak differences to determine if said peaks are representative of actual patient breaths.

17. The apparatus of claim 16, said program including hysteresis and time delays operable for eliminating false peak-to-peak values.

18. The apparatus of claim 16, said program comparing said peak-to-peak differences to the average peak-to-peak difference of a plurality of previous patient breaths.

19. The apparatus of claim 18, said plurality including the average of at least eight previously detected breaths.

20. The apparatus of claim 19, wherein an actual patient breath is determined when said peak-to-peak difference is greater than 40% of said average.

21. In a positive airway pressure apparatus including a gas delivery unit operable to deliver pressurized gas to a patient'"'"'s airway during successive patient breath cycles, a sensor operably connected with said unit, and a controller coupled with said sensor, the improvement which comprises:

said sensor operable to measure a patient breath-indicating parameter selected from the group consisting of pressure, air flow direction and combinations thereof in said unit and to generate a sensor output corresponding to said parameter;

said controller receiving said sensor output for analyzing the output to determine use or non-use of the apparatus by the patient as a function of said measured parameter;

said gas delivery unit including a blower unit and a conduit connected with said blower unit and adapted for coupling with a patient, said blower unit delivering pressurized gas through said conduit to the patient; and

said sensor including a tubular probe having a probe tip positioned in said conduit and oriented within the confines of said conduit in order to intersect gas flow through the conduit, said probe having an opposed probe end, said probe tip configured for producing varying pressure in said probe that vary according to said air flow direction in said conduit.

22. The apparatus of claim 21, said probe tip further including an open end and an upstanding vane on one side thereof for producing a differential pressure across the probe tip in response to air flow thereacross and thereby for producing said varying pressure in response to varying air flow across said probe tip.

23. The apparatus of claim 21, said tubular probe configured to permit air flow between said probe tip and said opposed probe end.