Systems and methods for hypotension

• US 20050283197A1
• Filed: 05/31/2005
• Published: 12/22/2005
• Est. Priority Date: 04/10/2001
• Status: Abandoned Application

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Scheiner, Avram, Daum, Douglas R.
• Application Number:
  US11/141,260
• Publication Number:
  US 20050283197A1
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/3605 Implantable neurostimulators for stimulating central or peripheral nerve system
• CPC Class Codes: A61N 1/3625 External stimulators
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration

Abstract

This document discusses, among other things, systems and methods that detect hypotension based on a measurement of thoracic impedance. It also provides an alert, a logging, or a therapy to treat the hypotension. Examples of anti-hypotension therapies include, among other things, pacing therapy, neural stimulation therapy, drug infusion therapy, or gene therapy.

Claims

1. A machine-assisted method including:

detecting a thoracic impedance signal associated with a portion of a subject'"'"'s thorax; and

providing a therapy at least in part in response to a baseline portion of the detected thoracic impedance below about 0.5 Hz indicating a fluid shift away from the thorax, the therapy assisting to shift fluid back toward the thorax.

2. The method of claim 1, in which the providing the therapy includes providing a non-pacing therapy.

3. The method of claim 1, in which the providing the therapy includes providing a non-pacing therapy and a pacing therapy.

4. The method of claim 2, in which the providing the non-pacing therapy includes stimulating an autonomic nervous system.

5. The method of claim 2, in which the providing the non-pacing therapy includes providing or controlling a gene therapy.

6. The method of claim 2, in which the providing the non-pacing therapy includes delivering a drug.

7. The method of claim 1, further including detecting a motion of the subject and providing the therapy based at least in part on the detected motion of the subject.

8. The method of claim 1, further including detecting a breathing of the subject and providing the therapy based at least in part on the detected breathing.

9. The method of claim 1, in which providing the therapy includes adjusting the therapy based on frequency components of the thoracic impedance associated with fluid shift away from the thorax and associated with the subject'"'"'s breathing.

10. The method of claim 1, in which providing the therapy includes providing a drug to the subject in response to an increase in detected thoracic impedance at a frequency associated with fluid shift away from the thorax.

11. The method of claim 1, in which the detecting the thoracic impedance signal includes detecting a thoracic fluid shift signal having a frequency component that is less than or equal to a cutoff frequency value that is between 0.01 Hz and 0.5 Hz inclusive.

12. The method of claim 1, in which the providing the therapy includes treating both a hypotension associated with a change in a subject'"'"'s posture and a hypotension that is not associated with a change in the subject'"'"'s posture.

13. An implantable medical device, configured to utilize first and second electrodes associated with a portion of a subject'"'"'s thorax, the implantable medical device comprising:

a thoracic signal detection module, for coupling to the first and second electrodes to receive a thoracic impedance signal;

an averager/lowpass filter that obtains a baseline portion of the thoracic impedance signal below about 0.5 Hz that is associated with a fluid shift away from the thorax; and

a therapy module to provide therapy to the subject using the baseline portion of the thoracic impedance signal, the therapy assisting to shift fluid back toward the thorax.

14. The device of claim 13, in which the averager/lowpass filter attenuates a breathing portion of the thoracic impedance signal, and in which the lowpass filter attenuates a cardiac stroke portion of the thoracic impedance signal.

15. The device of claim 13, in which the therapy module includes an autonomic nervous system stimulation circuit.

16. The device of claim 13, in which the therapy module includes a pacing circuit.

17. The device of claim 13, in which the therapy module includes an infusion dispenser.

18. The device of claim 13, in which the therapy module includes a gene therapy controller.

19. The device of claim 13, further including a motion detector circuit, and in which the therapy module provides the therapy based at least in part on the detected motion of the subject.

20. The device of claim 13, further including a respiration filter, coupled to the thoracic signal detection module to detect a breathing of the subject, and in which the therapy module is coupled to the respiration filter, and in which the therapy module provides the therapy based at least in part on the detected breathing.

21. A machine-assisted method including:

detecting a thoracic impedance signal associated with a portion of a subject'"'"'s thorax; and

providing an alert at least in part in response to a baseline portion of the detected thoracic impedance below about 0.5 Hz indicating a fluid shift away from the thorax, the therapy assisting to shift fluid back toward the thorax.

22. The method of claim 21, in which the providing the alert includes communicating from an implantable device to an external device.

23. The method of claim 21, in which the providing the alert includes communicating from an implantable device to a nearby first external device and communicating from the nearby first external device to an allowably distant second external device.

24. The method of claim 21, in which the providing the alert includes providing the alert to be discernable to the subject.

25. The method of claim 21, comprising providing a therapy at least in part in response to a baseline portion of the detected thoracic impedance below about 0.5 Hz indicating a fluid shift away from the thorax, the therapy assisting to shift fluid back toward the thorax.

26. The method of claim 25, in which the providing the therapy includes providing a pacing therapy.

27. The method of claim 25, in which the providing the therapy includes providing a non-pacing therapy.

28. The method of claim 25, in which the providing the therapy includes stimulating an autonomic nervous system.

29. The method of claim 25, in which the providing the therapy includes providing a drug.

30. The method of claim 25, in which the providing the non-pacing therapy includes providing a gene therapy.

31. The method of claim 21, including detecting a motion of the subject and providing the alert based at least in part on the detected motion of the subject.

32. The method of claim 21, including:

logging at least one hypotension episode; and

communicating information about the at least one hypotension episode.

33. An implantable medical device, configured to utilize first and second electrodes associated with a portion of a subject'"'"'s thorax, the implantable medical device comprising:

a thoracic signal detection module, for coupling to the first and second electrodes to receive a thoracic impedance signal;

an averager/lowpass filter that obtains a baseline portion of the thoracic impedance signal below about 0.5 Hz that is associated with a fluid shift away from the thorax; and

an alert module to provide an alert using the baseline portion of the thoracic impedance signal indicating a hypotension episode in which fluid shifts away from the thorax.

34. The device of claim 33, in which the alert module includes a telemetry circuit to communicate the alert from the implantable medical device to an external device.

35. The device of claim 33, in which the alert module includes a vibrator.

36. The device of claim 33, in which the alert module includes an electrical-to-audible signal transducer.

37. The device of claim 33, including a pacing circuit to deliver or adjust pacing therapy in response to the thoracic impedance signal indicating a fluid shift away from the thorax.

38. The device of claim 33, including a non-pacing therapy module to deliver or adjust therapy in response to the thoracic impedance signal indicating a fluid shift away from the thorax.

39. The device of claim 38, in which the non-pacing therapy module includes an autonomic nervous system stimulator.

40. The device of claim 38, in which the non-pacing therapy module includes an infusion dispenser.