Fault diagnosis in CPAP and NIPPV devices

• US 6,591,834 B1
• Filed: 06/05/2001
• Issued: 07/15/2003
• Est. Priority Date: 11/05/1998
• Status: Expired due to Term

• Current Assignee: ResMed Pty Ltd. (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Kenyon, Barton J., Colla, Gregory A.
• Primary Examiner(s): Lo, Weilun
• Assistant Examiner(s): MITCHELL, TEENA KAY
• Application Number:
  US09/719,680
• Time in Patent Office: 770 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.22, 128/204.23, 128/204.26, 128/205.23, 128/205.11, 128/204.29, 128/204.25
• US Class Current: 128/204.21
• 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 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0051 with alarm devices
• 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 16/0666 Nasal cannulas or tubing devices for improving normal breathing through the nose A61F5/08; nose filters A62B23/06; outside holding devices A61M25/02
• CPC Class Codes: A61M 16/08 Bellows; Connecting tubes having means for taking samples G01N1/22; Water traps; Patient circuits
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 16/16 Devices to humidify the respiration air A61M16/1045 takes precedence
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/003 with a flowmeter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/12 with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/70 with testing or calibration facilities
• CPC Class Codes: A61M 2205/707 : Testing of filters for clogging
• CPC Class Codes: A61M 2230/40 : Respiratory characteristics

Abstract

A ventilation device for non-invasive positive pressure ventilation (NIPPV) or continuous positive airway pressure (CPAP) treatment of a patient has a gas flow generator, a gas delivery circuit optionally including a humidifier, a controller and sensors monitoring values of operational parameters of the device. The device further includes one or more relationships stored in data storage of the controller relating combinations of parameter values as being indicative of fault conditions of the device operation, the sensors and/or the fault detection process.

Claims

1. A method of detecting a fault in an apparatus for supplying breathable gas to a patient at a positive pressure, the apparatus including a gas flow generator comprising a servo controlled motor and impeller, a motor speed transducer configured to monitor motor speed, a pressure transducer configured to monitor pressure developed by the gas flow generator, and a timer, the method comprising:

monitoring the motor speed;

monitoring the pressure;

following a predetermined duration, comparing the pressure to a first threshold and the motor speed to a second threshold to derive a first compared value and a second compared value, respectively; and

determining a pressure transducer fault in accordance with the first compared value and the second compared value.

2. The method of claim 1, further comprising determining that the pressure transducer is stuck low if the first compared value indicates that the pressure is below the first threshold and if the second compared value indicates that the motor speed is above the second threshold.

3. The method of claim 2, wherein the first threshold is approximately 2 cm H₂O.

4. The method of claim 2, wherein the second threshold is approximately 12,000 RPM.

5. The method of claim 1, wherein the predetermined duration is approximately 0.3s.

6. The method of claim 1, further comprising determining that the pressure transducer is stuck high if the first compared value indicates that the pressure is above the first threshold and if the second compared value indicates that the motor speed is below the second threshold.

7. The method of claim 6, wherein the first threshold is approximately 15 cm H₂O.

8. The method of claim 6, wherein the second threshold is approximately 4,500 RPM.

9. A method of operating an apparatus for supplying breathable gas to a patient at a positive pressure, the apparatus including a gas flow generator comprising a servo controlled motor and impeller, a motor speed transducer, a pressure transducer configured to monitor pressure developed by the gas flow generator, and a display, the method comprising:

determining a pressure transducer fault;

disabling the servo controlled motor and impeller; and

providing a warning notice on the display.

10. The method of claim 9, further comprising determining whether the pressure transducer is stuck high or stuck low.

11. An apparatus for supplying breathable gas to a patient at a positive pressure, including a gas flow generator comprising:

a servo controlled motor and impeller;

a motor speed transducer configured to monitor motor speed;

a pressure transducer configured to monitor pressure developed by the gas flow generator;

a timer; and

a controller configured to;

monitor the motor speed transducer, the pressure transducer, and the timer;

compare, following a predetermined duration, the pressure to a first threshold and the motor speed to a second threshold to derive a first compared value and a second compared value, respectively; and

determine a pressure transducer fault in accordance with the first compared value and the second compared value.

12. The apparatus of claim 11, wherein the controller is further configured to determine that the pressure transducer is stuck low if the first compared value indicates that the pressure is below the first threshold and if the second compared value indicates that the motor speed is above the second threshold.

13. The apparatus of claim 12, wherein the first threshold is approximately 2 cm H₂O.

14. The apparatus of claim 12, wherein the second threshold is approximately 12,000 RPM.

15. The apparatus of claim 11, wherein the predetermined duration is approximately 0.3s.

16. The apparatus of claim 11, wherein the controller is further configured to determine that the pressure transducer is stuck high if the first compared value indicates that the pressure is above the first threshold and if the second compared value indicates that the motor speed is below the second threshold.

17. The apparatus of claim 16, wherein the first threshold is approximately 15 cm H₂O.

18. The apparatus of claim 16, wherein the second threshold is approximately 4,500 RPM.

19. An apparatus for supplying breathable gas to a patient at a positive pressure, including a gas flow generator comprising:

a servo controlled motor and impeller;

a motor speed transducer;

a pressure transducer configured to monitor pressure developed by the gas flow generator;

a display; and

a controller configured to;

determine a pressure transducer fault;

disable the servo controlled motor and impeller; and

provide a warning notice on the display.

20. The apparatus of claim 19, wherein the controller is further configured to determine whether the pressure transducer is stuck high or stuck low.