Method and apparatus for detecting respiratory disturbances

• US 20040134496A1
• Filed: 04/21/2003
• Published: 07/15/2004
• Est. Priority Date: 01/10/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Sheldon, Todd J., Davie, Scott W., Erickson, Mark K., Cho, Yong K., Markowitz, H. Toby, Mongeon, Luc R., Ning, Steven L.
• Granted Patent: US 7,160,252 B2
• Time in Patent Office: Days
• US Class Current: 128/204.23
• 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 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2230/04 Heartbeat characteristics, e.g. ECG, blood pressure modulation
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/60 Muscle strain, i.e. measured on the user
• CPC Class Codes: A61M 2230/63 Motion, e.g. physical activity
• CPC Class Codes: A61M 2230/65 Impedance, e.g. conductivity, capacity

Abstract

A system and method for monitoring respiration including sensing a signal that varies with respiration, deriving a respiration parameter, applying criteria for detecting a respiration disturbance and determining one or more respiratory disturbance metrics. The system preferably includes an implantable sensor with an associated implantable medical device such that chronic respiration monitoring is possible. The implantable medical device may execute methods for detecting and measuring respiratory disturbances or may store data to be transferred to an external device for detecting and measuring respiratory disturbances. Respiratory disturbance detection may trigger a responsive action such as physiological data storage, a change in therapy delivery, or a clinician warning. Assessment of cardiac function may be made based on metrics of respiratory disturbances or a measure of circulatory delay time following detection of a respiratory disturbance.

Claims

1. A method for detecting a respiratory disturbance, comprising:

sensing a physiological signal containing a frequency or an amplitude component related to at least two respiratory cycles;

deriving at least one respiratory parameter from the physiologic signal; and

detecting a respiratory disturbance event when the at least one respiratory parameter meets or exceeds a predetermined criteria threshold for detecting the respiratory disturbance.

2. A method according to claim 1, further including measuring the magnitude of a characteristic of the respiratory disturbance.

3. A method of claim 2, wherein a measure of the respiratory disturbance is at least a one of:

an apnea duration;

a hypopnea duration;

a hyperpnea duration;

a periodic breathing cycle length.

4. A method according to claim 1, wherein the physiological signal is at least a one of:

a thoracic impedance;

an ECG signal;

an EGM signal;

a blood pressure signal;

an activity level measurement;

an oxygen saturation measurement.

5. A method according to claim 1, wherein the respiratory disturbance comprises Kussmaul breathing.

6. A method according to claim 1, wherein the respiratory disturbance is Cheyne-Stokes respiration.

7. A method according to claim 1, wherein the respiratory disturbance is sleep apnea.

8. A method according to claim 1, further including a step of determining a circulatory delay time comprising:

measuring an oxygen saturation; and

determining the time between the end of the respiratory disturbance and a subsequent minimum or a subsequent maximum oxygen saturation.

9. A method according to claim 8, further including a step of determining an estimate of cardiac output based on the circulatory delay time.

10. A method according to claim 3, further including a step of determining an estimate of cardiac function based on a metric of the respiratory disturbance.

11. A method according to claim 1, further including a step of triggering the storage of physiological data upon the detection of the respiratory disturbance.

12. A method according to claim 1, further including a step of triggering a therapy based at least in part upon detection of the respiratory disturbance.

13. A method according to claim 1, further including a step of generating a warning to alert a clinician or a patient upon detection of the respiratory disturbance.

14. A method according to claim 9, further comprising determining a heart failure status of a patient in the event that the estimate of cardiac function is lower than a predetermined lower threshold.

15. A method according to claim 14, further comprising the step of storing a plurality of data related to the estimated cardiac output over a period of time.

16. A device for detecting a respiratory disturbance, comprising:

means for sensing a physiological signal containing a frequency component or an amplitude component related to a common characteristic of at least two respiratory cycles;

means for deriving at least one respiratory parameter from the physiologic signal; and

means for detecting a respiratory disturbance event when the at least one respiratory parameter meets or exceeds a predetermined criteria threshold for detecting the respiratory disturbance.

17. A computer readable medium for storing a set of computer instructions for performing the following method:

instructions for sensing a physiological signal containing a frequency component or an amplitude component related to a common characteristic of at least two respiratory cycles;

instructions for deriving at least one respiratory parameter from the physiologic signal; and

instructions for detecting a respiratory disturbance event when the at least one respiratory parameter meets or exceeds a predetermined criteria threshold for detecting the respiratory disturbance.

18. A method according to claim 17, further including:

instructions for measuring the magnitude of a characteristic of the respiratory disturbance.

19. A method of claim 18, wherein a measure of the respiratory disturbance is at least a one of:

an apnea duration;

a hypopnea duration;

a hyperpnea duration;

a periodic breathing cycle length.

20. A method according to claim 17, wherein the physiological signal is at least a one of:

a thoracic impedance;

an ECG signal;

an EGM signal;

a blood pressure signal;

an activity level measurement;

an oxygen saturation measurement.

21. A method according to claim 17, wherein the respiratory disturbance comprises Kussmaul breathing.

22. A method according to claim 17, wherein the respiratory disturbance comprises a Cheyne-Stokes respiration event.

23. A method according to claim 17, wherein the respiratory disturbance comprises a sleep apnea event.

24. A method according to claim 17, further including a step of determining a circulatory delay time, comprising:

instructions for measuring an oxygen saturation; and

instructions for determining the time between the end of the respiratory disturbance and a subsequent minimum or a subsequent maximum oxygen saturation.

25. A method according to claim 24, further comprising:

instructions for determining an estimate of cardiac output based on the circulatory delay time.

26. A method according to claim 19, further including a step of instructions determining an estimate of cardiac function based on a metric of the respiratory disturbance.

27. A method according to claim 17, further comprising instructions for triggering the storage of a physiological data item upon the detection of the respiratory disturbance.

28. A method according to claim 17, further comprising instructions for triggering a therapy based at least in part upon detection of the respiratory disturbance.

29. A method according to claim 17, further comprising instructions for generating a warning to alert a clinician or a patient of the detection of the respiratory disturbance.

30. A method according to claim 25, further comprising instructions for determining a heart failure status of a patient in the event that the estimate of cardiac function is lower than a predetermined lower threshold.