Measurement of patient physiological parameters

• US 8,521,293 B2
• Filed: 02/13/2012
• Issued: 08/27/2013
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: CVRx, Inc.
• Original Assignee: CVRx, Inc.
• Inventors: Anderson, Russell Eugene, Yared, Nadim, Stroebel, John Charles, Kieval, Robert S, Check, Steve, Lovett, Eric
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): Morales, Jon Eric C
• Application Number:
  US13/372,412
• Publication Number:
  US 20120149998A1
• Time in Patent Office: 561 Days
• Field of Search: 600/436, 600/345, 600/547, 607/44, 607/62
• US Class Current: 607/44
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/6862 Stents
• CPC Class Codes: A61B 5/6876 Blood vessel
• CPC Class Codes: A61N 1/36062 Spinal stimulation
• CPC Class Codes: A61N 1/36117 for treating hypertension
• CPC Class Codes: A61N 1/36139 with automatic adjustment

Abstract

A method of determining one or more physiological parameter of a patient by providing a plurality of implantable electrodes proximate a blood vessel of the patient, applying a measurement signal through the plurality of electrodes, the measurement signal having a known parameter, obtaining a resultant signal through the plurality of electrodes, the resultant signal having a resultant parameter, calculating vascular impedance based on the measurement signal and the resultant signal, and calculating a physiological parameter based on the vascular impedance. In some embodiments, the physiological parameter is utilized to modify a therapy signal controlling therapy delivered to the patient.

Claims

1. A method of calibrating an implantable system, the system including a first electrode, a second electrode, and a control system coupled to the first and second electrodes, wherein the first and second electrodes are implanted in contact with a wall of a blood vessel of a patient, the method comprising:

applying a measurement signal with the control system to the first electrode, the measurement signal having a known parameter;

obtaining a resultant signal through the second electrode, the resultant signal having a resultant parameter;

calculating impedance of the blood vessel based on the measurement signal and the resultant signal;

contemporaneously obtaining a blood pressure measurement of the patient;

comparing the impedance of the blood vessel to the blood pressure measurement to determine a patient-specific relationship between blood vessel impedance and blood pressure; and

storing the patient-specific relationship in a memory of the control system.

2. The method of claim 1, wherein contemporaneously obtaining the blood pressure measurement is accomplished via a sphygmomanometer.

3. The method of claim 1, wherein contemporaneously obtaining the blood pressure measurement is accomplished via a temporarily implanted pressure transducer.

4. The method of claim 1, further comprising delivering a therapy signal from the control system, the therapy signal based at least in part on the patient-specific relationship stored in the memory of the control system.

5. The method of claim 4, wherein the therapy signal comprises the measurement signal.

6. The method of claim 1, further comprising storing the blood pressure measurement in the memory as a baseline blood pressure measurement.

7. The method of claim 1, further comprising:

contemporaneously obtaining a second blood pressure measurement;

calculating a subsequent impedance of the blood vessel based on a second measurement signal and a second resultant signal;

comparing the subsequent impedance and the second blood pressure measurement to the patient-specific relationship stored in the memory; and

recalibrating the patient-specific relationship if the subsequent impedance of the blood vessel does not correlate to the second blood pressure measurement according to the patient-specific relationship.

8. The method of claim 1, wherein the measurement signal has a frequency between 10 Hz and 50 Hz.

9. The method of claim 1, wherein at least one of the first and second electrodes are implanted in contact with a blood vessel of a patient selected from the group consisting of:

a carotid sinus, an aortic arch, a common carotid artery, a subclavian artery, a brachiocephalic artery, pulmonary artery, pulmonary vein, jugular vein, femoral artery, femoral vein, and a heart.

10. A method, comprising:

causing a system to be manufactured and made available to a user, the system including a first electrode, a second electrode, and a control system coupled to the first electrode and the second electrode;

providing instructions to the user, the instructions comprising;

implanting the system such that each of the first and second electrodes are implanted in contact with a wall of a blood vessel;

applying a measurement signal with the control system to the first electrode, the measurement signal having a known parameter;

obtaining a resultant signal through the second electrode, the resultant signal having a resultant parameter;

causing the control system to calculate an impedance of the blood vessel based on the measurement signal and the resultant signal;

contemporaneously obtaining a blood pressure measurement of the patient;

causing the control system to compare the impedance of the blood vessel to the blood pressure measurement to determine a patient-specific relationship between blood vessel impedance and blood pressure; and

causing the control system to store the patient-specific relationship in a memory of the control system.

11. The method of claim 10, wherein contemporaneously obtaining the blood pressure measurement is accomplished via a sphygmomanometer.

12. The method of claim 10, wherein contemporaneously obtaining the blood pressure measurement is accomplished via a temporarily implanted pressure transducer.

13. The method of claim 10, the instructions further comprising causing the control system to deliver a therapy signal from the control system to at least one of the electrodes, the therapy signal based at least in part on the patient-specific relationship stored in the memory of the control system.

14. The method of claim 13, wherein the therapy signal comprises the measurement signal.

15. The method of claim 10, wherein the measurement signal has a frequency between 10 Hz and 50 Hz.

16. The method of claim 10, wherein the instructions are provided to the user and/or the control system.

17. The method of claim 10, wherein at least one of the first and second electrodes are implanted in contact with a blood vessel of a patient selected from the group consisting of:

a carotid sinus, an aortic arch, a common carotid artery, a subclavian artery, a brachiocephalic artery, pulmonary artery, pulmonary vein, jugular vein, femoral artery, femoral vein, and a heart.

18. A method of determining a physiological parameter of a patient, comprising:

applying a measurement signal through a plurality of electrodes implanted in contact with a wall of a blood vessel of the patient, the measurement signal having a known parameter and a frequency between 10 Hz and 50 Hz;

obtaining a resultant signal through the plurality of electrodes, the resultant signal having a resultant parameter;

calculating impedance of the blood vessel based on the measurement signal and the resultant signal; and

determining a physiological parameter based on the impedance of the blood vessel.

19. The method of 18, wherein the measurement signal has a frequency of about 10 Hz, and wherein the physiological parameter comprises respiration.

20. The method of 18, wherein the measurement signal has a frequency of about 20 Hz, and wherein the physiological parameter comprises heart rate.

21. The method of 18, wherein the measurement signal has a frequency between 20 Hz and 50 Hz, and wherein the physiological parameter comprises blood pressure.