USING ACOUSTIC ENERGY TO COMPUTE A LUNG EDEMA FLUID STATUS INDICATION

• US 20090036777A1
• Filed: 08/03/2007
• Published: 02/05/2009
• Est. Priority Date: 08/03/2007
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Zhang, Yongxing, Zarembo, Paul E., Zhang, Yunlong
• Granted Patent: US 8,221,323 B2
• Time in Patent Office: Days
• US Class Current: 600/459
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/4472 Wireless probes

Abstract

Systems and methods for monitoring lung edema fluid status, such as monitoring the presence or absence of pulmonary edema, in a subject using information about responsive acoustic energy echoes from a lung are described. The system comprises, among other things, an implantable device including an acoustic transducer configured to emit acoustic energy to a lung and to receive one or more responsive acoustic energy echoes from a lung. In an example, the implantable device includes a cardiac function management device having an acoustic window in a body thereof. In another example, the implantable device includes one or more subcutaneous leads. An implantable or external processor circuit is configured to receive information about the acoustic energy echoes to compute and provide a lung edema fluid status indication; such information may include an increased number or special pattern of acoustic energy echoes received or a decreased time between successively received echoes.

Claims

1. A system comprising:

a fully implantable device including an acoustic transducer configured to emit acoustic energy to a lung and to receive a responsive acoustic energy echo from a lung; and

an implantable or external processor circuit configured to receive information about the acoustic energy echo and to use the information about the acoustic energy echo to compute and provide a lung edema fluid status indication.

2. The system of claim 1, wherein the information about the acoustic energy echo includes a number of acoustic energy echoes per unit of time.

3. The system of claim 1, comprising an external user-interface device communicatively coupled to the implantable device and including a user-detectable indication of lung edema fluid status derived from the information about the acoustic energy echo.

4. The system of claim 1, comprising a transducer pulse control circuit configured to control at least one of an amplitude, a frequency, or a duration of the acoustic energy emitted from the acoustic transducer and thereby provide a level of confidence in the computed lung edema fluid status indication.

5. The system of claim 1, comprising a comparator circuit configured to compare an energy of the acoustic energy echo to a stored specified threshold, algorithm, pattern, or data array;

and

wherein the processor circuit is configured to also use information about the comparison to compute the lung edema fluid status indication.

6. The system of claim 1, comprising a timing circuit configured to trigger a recurrent emitting of the acoustic energy synchronized with a specified phase of one or both of a subject'"'"'s respiratory cycle or cardiac cycle.

7. The system of claim 1, comprising a regimen control circuit configured to initiate or adjust a regimen provided to a subject using information about the acoustic energy echo.

8. The system of claim 1, comprising a pressure sensor configured to provide a blood pressure-indicating signal indicative of blood pressure in a pulmonary artery;

and

wherein the processor circuit includes an input to receive the blood pressure-indicating signal, and the processor circuit is configured to also use information about the blood pressure-indicating signal to compute the lung edema fluid status indication.

9. The system of claim 1, comprising an electrical impedance measurement circuit configured to inject an electrical energy between two or more electrodes and to concurrently measure a response thereto in a thoracic region of a subject between the same or different two or more electrodes to provide a thoracic impedance-indicating signal;

and

wherein the processor circuit includes an input to receive the thoracic impedance-indicating signal, and the processor circuit is configured to also use information about the thoracic impedance-indicating signal to compute the lung edema fluid status indication.

10. The system of claim 1, wherein the implantable device includes a cardiac function management device having a device body, the device body including an acoustic window disposed such that the acoustic energy is emitted or responsive acoustic energy is received therethrough in a direction of a lung when the device body is implanted in a pectoral region.

11. The system of claim 1, wherein the implantable device includes one or more subcutaneous leads, each lead having a lead body extending from a proximal end portion to a distal end portion and having an intermediate portion therebetween;

and

wherein at least one of the intermediate portion or the distal end portion includes the acoustic transducer.

12. The system of claim 1, wherein the acoustic energy includes a frequency within an inclusive range of about 20 KHz to about 10 MHz.

13. A method comprising:

emitting acoustic energy toward a lung using a fully implantable device;

receiving and processing an acoustic energy echo; and

computing and providing a lung edema fluid status indication using information about the acoustic energy echo.

14. The method of claim 13, wherein computing and providing the lung edema fluid status indication includes recognizing at least one of an increase in the number of acoustic energy echoes received or a decrease in time between successively received acoustic energy echoes.

15. The method of claim 13, comprising providing a user-detectable indication of lung edema fluid status, including displaying information about the acoustic energy echo.

16. The method of claim 13, comprising automatically determining the presence or absence of one or more comet-tail-like artifacts using a programmably learned or defined algorithm.

17. The method of claim 13, comprising programmably or automatically changing at least one of an amplitude, a frequency, pulse shape, or a duration of the acoustic energy.

18. The method of claim 13, comprising programmably or automatically selecting which one or more acoustic transducers are used to emit the acoustic energy.

19. The method of claim 13, comprising storing information about instances of the acoustic energy echo over a period of time that exceeds a respiration cycle length.

20. The method of claim 13, comprising measuring an indication of pulmonary artery blood pressure;

and also using the indication of pulmonary artery blood pressure to compute the lung edema fluid status indication.

21. The method of claim 13, comprising measuring an indication of thoracic impedance;

and

also using the indication of thoracic impedance to compute the lung edema fluid status indication.

22. The method of claim 13, comprising measuring an indication of at least one heart sound;

and

also using the indication of heart sound to compute the lung edema fluid status indication.

23. The method of claim 13, comprising measuring at least one of a blood flow indication, a heart size indication, a venous pressure indication, a respiration rate indication, or an associated rate of change thereof;

and

also using at least one of the blood flow indication, the heart size indication, the venous pressure indication, the respiration rate indication, or the associate rate of change thereof to compute the lung edema fluid status indication.

24. The method of claim 13, comprising adjusting an orientation of the acoustic transducer via adjusting a set-screw associated with the transducer.

25. The method of claim 13, comprising adjusting an orientation of the acoustic transducer via activating an implanted motor associated with the transducer.

26. The method of claim 13, wherein emitting acoustic energy includes emitting ultrasonic energy toward the lung using the fully implantable device.

27. The method of claim 13, wherein emitting acoustic energy toward the lung includes steering the acoustic energy from at least one of a left or a right pectoral region of a subject.

28. The method of claim 13, wherein emitting acoustic energy toward the lung includes using at least one reference marker disposed on a lead or fixated to a portion of a subject.