MASK ASSEMBLY, SYSTEM AND METHOD FOR DETERMINING THE OCCURRENCE OF RESPIRATORY EVENTS USING FRONTAL ELECTRODE ARRAY

• US 20070208269A1
• Filed: 04/26/2007
• Published: 09/06/2007
• Est. Priority Date: 05/18/2004
• Status: Abandoned Application

• Current Assignee: Natus Medical Incorporated
• Original Assignee: Natus Medical Incorporated
• Inventors: Kurtz, Ronald, Mumford, John, Wu, Jianping
• Application Number:
  US11/740,717
• Publication Number:
  US 20070208269A1
• Time in Patent Office: Days
• US Class Current: 600/546
• 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 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/103 Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/296 for electromyography [EMG]
• CPC Class Codes: A61B 5/398 Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]
• CPC Class Codes: A61B 5/4806 Sleep evaluation A61B5/4821 takes precedence; devices for inducing sleep A61M21/02
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: A61B 5/4815 Sleep quality
• 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 5/6814 Head
• CPC Class Codes: A61M 16/0051 with alarm devices
• 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 16/0633 with forehead support
• CPC Class Codes: A61M 16/0683 Holding devices therefor
• 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 2016/0036 : in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2205/3553 : remote, e.g. between patient's home and doctor's office
• CPC Class Codes: A61M 2205/3561 : local, e.g. within room or hospital
• CPC Class Codes: A61M 2205/3592 : using telemetric means, e.g. radio or optical transmission
• CPC Class Codes: A61M 2205/52 : with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 2205/8206 : battery-operated
• 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 2230/10 : Electroencephalographic signals
• CPC Class Codes: A61M 2230/18 : Rapid eye-movements [REM]
• CPC Class Codes: A61M 2230/205 : partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/435 : partial O2 pressure (P-O2)
• CPC Class Codes: A61M 2230/62 : Posture
• CPC Class Codes: A61M 2230/63 : Motion, e.g. physical activity

Abstract

Embodiments of the invention relate to methods, systems and mask assemblies for use in determining the occurrence of respiratory events using a frontal electrode array. The methods, systems and mask assemblies involve use of means for flow measurement of breathing gas of a person, blood oxygen saturation measurement means and a frontal electrode array for measuring frontal bioelectric signals, each of which is coupled to a processing unit. The processing unit is configured to determine the occurrence of at least one of an apnea event and a hypopnea event based on the measurement signals. Some embodiments involve calculation of an apnea-hypopnea index (AHI) based on the determined apnea and hypopnea events over a period of time.

Claims

1. A system for determining the occurrence of respiratory events, comprising:

a plurality of electrodes positionable at frontal locations on a person'"'"'s forehead to sense bioelectric signals;

a measurement device for measuring respiratory flow of the person;

a blood oximeter device for measuring a blood oxygen saturation of the person; and

a processing unit coupled to the plurality of electrodes, the flow measurement device and the blood oximeter device, wherein the processing unit is configured to determine a sleep state of the person based on the bioelectric signals, to determine the occurrence of an apnea event based on the sleep state and the respiratory flow and to determine the occurrence of a hypopnea event based on the respiratory flow, the sleep state of the person and the blood oxygen saturation.

2. The system of claim 1, wherein the sleep state is one of awake and asleep.

3. The system of claim 1, wherein the sleep state is one of wake, sleep stage one, sleep stage two, deep sleep, REM sleep and movement time.

4. The system of claim 1, wherein the plurality of electrodes are located on a forehead member for positioning on the forehead.

5. The system of claim 4, wherein the plurality of electrodes comprises a first electrode located on a projecting portion of the forehead member for positioning adjacent a nasion area of the head, a second electrode located on the forehead member for positioning over a first lateral forehead area and a third electrode located on the forehead member for positioning over a second lateral forehead area opposite the first lateral forehead area.

6. The system of claim 5, wherein conductors are formed on the forehead member for electrically coupling the first, second and third electrodes to an output connector.

7. The system of claim 5, further comprising a fourth electrode located on the forehead member intermediate the second and third electrodes for positioning over a central forehead area.

8. The system of claim 5, wherein the second and third electrodes are located on the forehead member for positioning higher on the forehead than Fp1 and Fp2 electrode positions.

9. The system of claim 5, wherein the second and third electrodes are located on the forehead member for positioining laterally beyond respective Fp1 and Fp2 electrode positions.

10. The system of claim 4, wherein the forehead member is flexible to accommodate varying forehead shapes.

11. The system of claim 10, wherein the forehead member comprises a flexible plastic substrate.

12. The system of claim 10, wherein the forehead member comprises a woven material.

13. The system of claim 4, wherein the first, second and third electrodes are removeably attachable to the forehead member.

14. The system of claim 1, wherein the processing unit is configured to determine the sleep state based on a plurality of rules applied in relation to the bioelectric signals.

15. The system of claim 14, further comprising a signal conditioning unit coupled to the processing unit for receiving detected electrical potentials from the plurality of electrodes, conditioning the electrical potentials to generate the biological signals and providing the biological signals to the processing unit.

16. The system of claim 14, wherein the plurality of rules are empirically derived based on correlation of physiological conditions with particular biological signals or signal patterns.

17. The system of claim 1, further comprising one or more sensors coupled to the processor and located away from the head for detecting movement of a body of the patient.

18. The system of claim 32, wherein the one or more sensors comprise one or more accelerometers.

19. The system of claim 32, wherein the one or more sensors comprise one or more electromyographic sensors.

20. The system of claim 4, wherein the blood oximeter device is located on the forehead member.

21. The system of claim 1, wherein the blood oximeter device is located on a finger or ear of the person.

22. The system of claim 1, further comprising an air supply interface for supplying positive airway pressure to an airway of the person, wherein the processing unit is configured to control the supply of positive airway pressure.

24. The system of claim 22, wherein the processing unit is further configured to determine a time duration within a designated period that the person is in a sleep state in which the person is asleep.

25. The system of claim 24, wherein the processing unit is further configured to determine an apnea-hypopnea index (AHI) based on the time duration and the number of occurrences of apnea and hypopnea events during at least part of the time duration.

26. The system of claim 25, wherein the processing unit is further configured to determine a therapeutic efficacy of the supplied positive airway pressure based on the AHI.

27. The system of claim 1, wherein the processing unit is further configured to determine a time duration that the person is in a sleep state in which the person is asleep.

28. The system of claim 27, wherein the processing unit is further configured to determine an apnea-hypopnea index (AHI) based on the time duration and the number of occurrences of apnea and hypopnea events during at least part of the time duration.

29. The system of claim 28, wherein the processing unit is further configured to determine whether the person has a sleep-related disorder based on the AHI.

30. The system of claim 27, wherein the processing unit is further configured to determine the occurrence of a respiratory effort related arousal (RERA) event based on the bioelectric signals and the measured respiratory flow.

31. The system of claim 30, wherein the processing unit is further configured to determine a respiratory distress index (RDI) based on the number of occurrences of apnea, hypopnea and RERA events during at least part of the time duration.

32. The system of claim 24, wherein the processing unit is further configured to monitor the occurrence of respiratory events during a first part of the designated period without supplying positive airway pressure to the airway and to monitor the occurrence of respiratory events during a second part of the designated period while supplying positive airway pressure to the airway.

33. The system of claim 32, wherein the processing unit is further configured to end the first part of the designated period and begin the second part of the designated period in response to determining that one or more criteria are satisfied in relation to the occurrence of respiratory events during the first part of the designated period.

34. The system of claim 1, wherein the processing unit is further configured to determine the occurrence of an arousal event based on the bioelectric signals and further configured to determine the occurrence of the hypopnea event based on the respiratory flow, the sleep state of the person and at least one of the arousal event and the blood oxygen saturation.

35. A method of determining the occurrence of respiratory events, comprising:

positioning a plurality of electrodes at frontal locations on a person'"'"'s forehead;

sensing bioelectric signals using the plurality of electrodes;

measuring respiratory flow of the person;

measuring a blood oxygen saturation of the person;

determining a sleep state of the person based on the bioelectric signals;

determining occurrence of an apnea event based on the sleep state and the respiratory flow; and

determining occurrence of a hypopnea event based on the respiratory flow, the blood oxygen saturation and the sleep state of the person.

23. The system of claim 37, wherein the air supply interface comprises a nasal or naso-oral interface.

36. The method of claim 35, further comprising determining a time duration within a designated period that the person is in a sleep state in which the person is asleep.

37. The method of claim 36, further comprising determining an apnea-hypopnea index (AHI) based on the time duration and the number of occurrences of apnea and hypopnea events during the time duration.

38. The method of claim 37, further comprising determining whether the person has a sleep-related disorder based on the AHI.

39. The method of claim 37, further comprising supplying positive airway pressure to an airway of the person during at least part of the time duration.

40. The method of claim 39, further comprising determining a therapeutic efficacy of the supplied airway pressure based on the AHI.

41. The method of claim 36, further comprising determining occurrence of a respiratory effort related arousal (RERA) event based on the bioelectric signals and the measure respiratory flow.

42. The method of claim 41, further comprising determining a respiratory distress index (RDI) based on the number of occurrences of apnea, hypopnea and RERA events during at least part of the time duration.

43. The method of claim 36, further comprising monitoring the occurrence of respiratory events during a first part of the designated period without supplying positive airway pressure to an airway of the person and monitoring the occurrence of respiratory events during a second part of the designated period while supplying positive airway pressure to the airway.

44. The method of claim 43, further comprising ending the first part of the designated period and beginning the second part of the designated period in response to satisfaction of one or more criteria in relation to at least one of:

the occurrence of respiratory events during the first part of the designated period;

time spent in one or more sleep states;

time spent in a body position; and

expiry of the first part of the designated period.

45. A system for determining the occurrence of respiratory events, comprising:

a plurality of electrodes positionable at frontal locations on a person'"'"'s forehead to sense bioelectric signals;

a measurement device for measuring respiratory flow of the person; and

a processing unit coupled to the plurality of electrodes and the flow measurement device, wherein the processing unit is configured to determine a sleep state of the person based on the bioelectric signals and to determine the occurrence of an arousal based on the bioelectric signals, and wherein the processing unit is further configured to determine the occurrence of an apnea event based on the sleep state and the respiratory flow and to determine the occurrence of a hypopnea event based on the respiratory flow, the sleep state of the person and the occurrence of an arousal.

46. A method of determining the occurrence of respiratory events, comprising:

positioning a plurality of electrodes at frontal locations on a person'"'"'s forehead;

sensing bioelectric signals using the plurality of electrodes;

measuring respiratory flow of the person;

determining a sleep state of the person based on the bioelectric signals;

determining occurrence of an arousal based on the bioelectric signals;

determining occurrence of an apnea event based on the sleep state and the respiratory flow; and

determining occurrence of a hypopnea event based on the respiratory flow, the sleep state and the arousal.