Method and apparatus for optimizing the continuous positive airway pressure for treating obstructive sleep apnea

• US 7,901,361 B2
• Filed: 04/18/2006
• Issued: 03/08/2011
• Est. Priority Date: 05/07/1992
• Status: Expired due to Fees

• Current Assignee: New York University
• Original Assignee: New York University
• Inventors: Norman, Robert G., Rapoport, David M.
• Primary Examiner(s): MARMOR II, CHARLES ALAN
• Application Number:
  US11/379,187
• Publication Number:
  US 20070016093A1
• Time in Patent Office: 1,785 Days
• Field of Search: None
• US Class Current: 600/533
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/6803 Head-worn items, e.g. helmets, masks, headphones or goggles
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/026 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 Class Codes: A61M 16/0677 Gas-saving devices therefor
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/04 Heartbeat characteristics, e.g. ECG, blood pressure modulation
• CPC Class Codes: A61M 2230/08 Other bio-electrical signals
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/62 Posture
• CPC Class Codes: A61M 39/228 with a tubular diaphragm constrictable by radial fluid force
• CPC Class Codes: G16H 20/40 relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A breathing apparatus is provided for the treatment of obstructive sleep apnea that optimizes the positive pressure to the airway of a patient. The apparatus is configured to detect flow limitations in the patient airway from an analysis of inspiratory flow waveforms. The airway pressure setting is raised, lowered or maintained depending on whether a flow limitation has been detected and on the previous actions taken by the apparatus. The apparatus may include a blower, a flow sensor, a pressure sensor, a microprocessor, a pressure controller and a nasal fitting. The apparatus is configured to increase the airway pressure when a flow limitation is detected in the airway of the patient and to decrease the airway pressure when a flow limitation is not detected.

Claims

1. A breathing device for optimizing the positive airway pressure to a patient, the device comprising:

a gas source to apply a positive pressure to the airway of a patient, said gas applied via a mask or nose fitting having an inlet adapted for coupling with the gas source;

a sensor configured to sense an inspiratory flow of breathing gas to the patient and to output signals relative to an inspiratory waveform of the patient;

a microprocessor in communication with the sensor sensing inspiratory flow of breathing gas to the patient, to receive signals relating to an inspiratory waveform, analyze the received signals, and generate control signals based at least upon the analysis of the received signals, wherein analyzing the received signals includes correlating data values associated with the received signals to a pure sine wave; and

a controller coupled to the breathing gas source and associated with the microprocessor, wherein the controller is configured to adjust the positive pressure in response to control signals received from the microprocessor.

2. The breathing device of claim 1, wherein the controller is further configured to increase the positive pressure to the airway of a patient when the signals relative to the inspiratory waveform indicate a flow limitation in the patient.

3. The breathing device of claim 2, wherein the controller is further configured to decrease the positive pressure to the airway of a patient when the signals relative to the inspiratory waveform do not indicate a flow limitation in the patient.

4. The breathing device of claim 1, wherein the microprocessor correlates the data values with a pure sine wave to calculate a sinusoidal index.

5. The breathing device of claim 1, wherein the microprocessor compares a regression fit of the data values with a regression fit of a pure sine wave to calculate a flatness index.

6. The breathing device of claim 1, wherein the microprocessor compares a ratio of a peak derivative of an early portion of the inspiratory waveform to a peak flow value of the inspiratory waveform to calculate a respiratory effort index.

7. The breathing device of claim 1, wherein the microprocessor analyzes a peak value of the inspiratory waveform, an average of a plurality of peak flow values for previous flow limited breaths, and an average of a plurality of peak flow values for previous non-flow limited breaths, and compares the average of the plurality of peak flow values for previous flow limited breaths with the average of the plurality of peak flow values for previous non-flow limited breaths as part of a relative flow index calculation.

8. The breathing device of claim 3, wherein the microprocessor determines a plurality of peak inspiratory flow values for flow limited breaths, determines a plurality of peak inspiratory flow values for non-flow limited breaths, correlates the signals relative to an inspiratory waveform with a pure sine wave to create a sinusoidal index, compares a regression fit of the signals relative to an inspiratory waveform with a regression fit of a pure sine wave to create a flatness index, compares a peak value of the signals relative to an inspiratory waveform with a peak value of a derivative of the signals relative to an inspiratory waveform to create an effort index, and analyzes a peak value of the signals relative to an inspiratory waveform, an average of the plurality of peak flow values for flow limited breaths, and an average of the plurality of peak flow values for non-flow limited breaths to create a relative flow magnitude index.

9. The breathing device of claim 8, wherein the microprocessor calculates a weighted index as a mathematical function of the sinusoidal index, the flatness index, the effort index and the relative flow magnitude index, wherein each index includes a weighted coefficient having a range including a value of zero.

10. The breathing device of claim 9, wherein the controller is configured to increase the positive pressure to the airway of a patient when the weighted index indicates a flow limitation in the patient, and wherein the controller is configured to decrease the positive pressure to the airway of a patient when the weighted index does not indicate a flow limitation in the patient.

11. The breathing device of claim 1, further including a non-volatile memory card device associated with the microprocessor, a blower driven by a motor, said mask or nose fitting having a vent, and wherein the controller is a motor speed controller connected to the motor.

12. The breathing device of claim 1, wherein the sensor comprises a flow sensor and/or a pressure sensor.

19. The breathing device of claim 4, wherein the microprocessor determines whether a flow limitation is present based at least on the calculated sinusoidal index.

20. The breathing device of claim 5, wherein the microprocessor determines whether a flow limitation is present based at least on the calculated flatness index.

13. A breathing device for optimizing the positive airway pressure to a patient, the device comprising:

a gas source to apply a positive pressure to the airway of a patient, said gas applied via a mask or nose fitting having an inlet adapted for coupling with the gas source;

a sensor configured to sense an inspiratory flow of breathing gas to the patient and to output signals relative to an inspiratory waveform of the patient;

a microprocessor in communication with the sensor sensing inspiratory flow of breathing gas to the patient, to receive signals relating to an inspiratory waveform, analyze the received signals, and generate control signals based at least upon analysis of the received signals, wherein analyzing the received signals includes analyzing a derivative relating to a rate of change of at least a portion of the inspiratory waveform; and

a controller coupled to the breathing gas source and associated with the microprocessor, wherein the controller is configured to adjust the positive pressure in response to control signals received from the microprocessor.

14. The breathing device of claim 13, wherein the microprocessor compares a ratio of a peak derivative of an early portion of the inspiratory waveform to a peak flow value of the inspiratory waveform to calculate a respiratory effort index.

15. The breathing device of claim 14, wherein the microprocessor determines whether a flow limitation is present based at least on the calculated respiratory effort index.

21. The breathing device of claim 13, wherein the derivative is a time-based derivative.

16. A breathing device for optimizing the positive airway pressure to a patient, the device comprising:

a gas source to apply a positive pressure to the airway of a patient, said gas applied via a mask or nose fitting having an inlet adapted for coupling with the gas source;

a sensor configured to sense an inspiratory flow of breathing gas to the patient and to output signals relative to an inspiratory waveform of the patient;

a microprocessor in communication with the sensor sensing inspiratory flow of breathing gas to the patient, to receive signals relating to an inspiratory waveform, analyze the received signals, and generate control signals based at least upon analysis of the received signals, wherein analyzing the received signals includes analyzing a peak value of the inspiratory waveform, an average of a plurality of peak flow values for previous flow limited breaths, and an average of a plurality of peak flow values for previous non-flow limited breaths; and

a controller coupled to the breathing gas source and associated with the microprocessor, wherein the controller is configured to adjust the positive pressure in response to control signals received from the microprocessor.

17. The breathing device of claim 16, wherein the microprocessor analyzes the peak value of the inspiratory waveform, the average of peak flow values for previous flow limited breaths, and the average of peak flow values for previous non-flow limited breaths to calculate a relative flow index.

18. The breathing device of claim 17, wherein the microprocessor determines whether a flow limitation is present based at least on the calculated relative flow index.