Method and apparatus for improving the comfort of CPAP

Patent metadata

Field	Value
Publication number	US-10293127-B2
Application number	US-201414527252-A
Country	US
Kind code	B2
Filing date	Oct 29, 2014
Priority date	Jun 20, 2003
Publication date	May 21, 2019
Grant date	May 21, 2019

Abstract

A low-cost CPAP apparatus in which, upon detection of the transition from inhalation to exhalation, the blower motor is de-energized to allow it to freewheel. When the pressure in the patient mask (or whatever interface is utilized) reaches a minimum pressure level during exhalation, the motor is re-energized and its speed is controlled so to maintain the pressure at a level suitable for exhalation. Upon detection of the transition from exhalation to inhalation, the motor speed is increased to provide higher pressures in the patient mask suitable for inhalation.

First claim

We claim:

1. An apparatus for delivering breathable air to a patient throughout the patient's respiratory cycle, the respiratory cycle including an inhalation phase and an exhalation phase, the apparatus comprising:
a blower having an electric motor configured to rotate an impeller within a volute;
a patient interface;
an air delivery conduit arranged to deliver breathable air from the blower to the patient interface;
at least one sensor adapted to sense a transition between the inhalation phase and the exhalation phase; and
a controller configured to control a speed of the electric motor to cause a pressure of the breathable air delivered to the patient interface to vary between a comfort pressure during at least a portion of the exhalation phase and a therapeutic pressure during at least a portion of the inhalation phase
wherein the controller is configured to:
predict when the inhalation phase will occur based upon a transition sensed by the at least one sensor; and
control an adjustment to the speed of the electric motor based on the prediction of when the inhalation phase will occur, and wherein the adjustment to the speed of the electric motor causes an increase in pressure from the comfort pressure to the therapeutic pressure to maintain synchrony between the blower and the patient's respiratory cycle,

wherein the controller includes a timer to record the time since the start of the exhalation phase, t e , and is configured to determine each of an average exhalation phase duration, t d , and a time required for an increase in pressure from the comfort pressure to the therapeutic pressure, t p , such that the electric motor is accelerated to cause an increase in pressure from the comfort pressure to the therapeutic pressure when t e =t d −t p .

2. An apparatus according to claim 1 wherein the controller is configured to commence increasing the pressure from the comfort pressure to the therapeutic pressure prior to the onset of the inhalation phase.

3. An apparatus according to claim 1 wherein the controller is configured to increase the pressure from the comfort pressure to the therapeutic pressure during at least a portion of the inhalation phase.

4. An apparatus according to claim 1 wherein the prediction of when the inhalation phase will occur is based on a negative peak detector configured to detect the exhalation phase's apex.

5. An apparatus according to claim 4 wherein the negative peak detector is further configured to determine a running average of a flow signal during the patient's respiratory cycle and fit a hysteresis to the running average of flow.

6. An apparatus according to claim 4 wherein the negative peak detector is further configured to filter a flow signal and calculate a flow differential.

7. An apparatus according to claim 1 wherein the controller is further configured to predict when the exhalation phase will occur and to control the adjustment to the speed to cause a decrease in pressure from the therapeutic pressure to the comfort pressure to maintain the synchrony.

8. An apparatus according to claim 7 wherein the controller is configured to commence decreasing the pressure from the therapeutic pressure to the comfort pressure prior to the detection of the onset of the exhalation phase.

9. An apparatus according to claim 7 wherein the controller is configured to decrease the pressure from the therapeutic pressure to the comfort pressure during at least a portion of the exhalation phase.

10. The apparatus according to claim 7 wherein the apparatus is further configured to detect the presence of an apnea and, upon detecting an apnea, the controller is configured to control the speed of the electric motor so as not to cause a decrease in pressure until the apparatus detects the cessation of the apnea.

11. The apparatus according to claim 1 wherein the at least one sensor is a flow sensor.

12. The apparatus according to claim 1 wherein the at least one sensor is an effort sensor.

13. The apparatus according to claim 1 wherein the at least one sensor is a pressure sensor.

14. The apparatus according to claim 1 , wherein the controller is configured to control the speed of the electric motor to cause the pressure of the breathable air delivered to the patient interface to be stable at a transition between negative flow and positive flow.

15. An apparatus for delivering breathable air to a patient throughout the patient's respiratory cycle, the respiratory cycle including an inhalation phase and an exhalation phase, the apparatus comprising:
a blower having an electric motor configured to rotate an impeller within a volute;
a patient interface;
an air delivery conduit arranged to deliver breathable air from the blower to the patient interface;
at least one sensor adapted to sense a transition between the inhalation phase and the exhalation phase;
a controller to control a pressure of the breathable air delivered to the patient interface to vary between a comfort pressure during at least a portion of the exhalation phase and a therapeutic pressure during at least a portion of the inhalation phase; and
a synchrony means to predict when the inhalation phase will occur based upon a transition sensed by the at least one sensor and to cause an adjustment in pressure between the comfort pressure and the therapeutic pressure based on the prediction of when the inhalation phase will occur, to maintain synchrony between the blower and the patient's respiratory cycle,
wherein the synchrony means includes a timer to record the time since the start of the exhalation phase, t e , and is configured to determine each of an average exhalation phase duration, t d , and a time required for an increase in pressure from the comfort pressure to the therapeutic pressure, t p , such that the electric motor is accelerated to cause an increase in pressure from the comfort pressure to the therapeutic pressure when t e =t d −t p .

16. An apparatus according to claim 15 wherein the synchrony means includes a negative peak detector configured to detect the exhalation phase's apex.

17. The apparatus according to claim 15 wherein the apparatus is further configured to detect the presence of an apnea and, upon detecting an apnea, the synchrony means is configured to halt any decrease in pressure until the apparatus detects the cessation of the apnea.

18. The apparatus according to claim 15 wherein the at least one sensor is one of: a flow sensor; an effort sensor; and a pressure sensor.

Assignees

• Resmed Ltd

Inventors

• Farrugia Steven Paul
• Alder Matthew
• Price Andrew Mikael
• Richard Ron

Classifications

• A61M16/022

  Control means therefor · CPC title

• A61M16/026 Primary

  specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis · CPC title

• A61M2016/0021

  with a proportional output signal, e.g. from a thermistor · CPC title

• A61M16/0003

  Accessories therefor, e.g. sensors, vibrators, negative pressure · CPC title

• A61M16/024

  including calculation means, e.g. using a processor · CPC title