Measurement of patient physiological parameters
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.
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.