Method for monitoring autonomic tone

• US 6,942,622 B1
• Filed: 07/29/2002
• Issued: 09/13/2005
• Est. Priority Date: 11/10/1999
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Turcott, Robert
• Primary Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US10/208,081
• Time in Patent Office: 1,142 Days
• Field of Search: 600/481, 600/485, 600/500, 600/504, 600508-509, 600/521, 600/526, 600/513, 600/517
• US Class Current: 600/508
• CPC Class Codes: A61B 2562/0204 Acoustic sensors
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• 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 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6817 Ear canal

Abstract

A method for monitoring the progression of the hemodynamic status of a patient by tracking autonomic tone. For example, the method may be applied to patients suffering from heart failure, diabetic neuropathy, cardiac ischemia, sleep apnea and hypertension. An implantable or other ambulatory monitor senses a pulse amplitude signal such as a vascular plethysmography signal. Variations of the signal amplitude on a scale greater than the heartbeat to heartbeat scale are indicative of variations in autonomic tone. A significant reduction in pulse amplitude and pulse amplitude variability are indicative of a heart failure exacerbation or other disease state change. This information may be used to warn the patient or healthcare providers of changes in the patient'"'"'s condition warranting attention.

Claims

1. A method for monitoring the progression of the disease state of a patient comprising the steps of;

(a) sensing a pulse amplitude signal indicative of cardiac contraction of said patient'"'"'s heart;

(b) identifying amplitude changes within said sensed signal over time;

(c) calculating a measure of autonomic tone based on said identified amplitude changes;

(d) repeating steps (a) through (c) to acquire a plurality of autonomic tone measures; and

(e) analyzing said plurality of autonomic tone measures to provide an indication of the progression of the disease state of said patient.

2. The method of claim 1 wherein said disease state comprises one or more of heart failure, diabetic neuropathy, cardiac ischemia, sleep apnea and hypertension.

3. The method of claim 1 wherein said step of sensing a pulse amplitude signal comprises sensing a vascular plethysmography signal.

4. The method of claim 1 and further including the step of storing a prescribed duration of the pulse amplitude signals in a long term memory.

5. The method of claim 1 wherein said step of sensing a pulse amplitude signal comprises sensing a measure of variability of said signal amplitude.

6. The method of claim 5 wherein said step (c) includes calculating a standard deviation of the pulse amplitudes.

7. The method of claim 1 wherein said step (e) includes the steps of calculating an average and a standard deviation of said plurality of autonomic tone measures.

8. The method of claim 7 and further including the step of determining a number n of a autonomic tone measures that differ by more than a prescribed amount from said average.

9. The method of claim 8 wherein said prescribed amount is a number greater than 1.5 time the calculated standard deviation.

10. The method of claim 1 and further including the step of using said output from step (e) to trigger a warning of the patient'"'"'s changing condition.

11. The method of claim 10 wherein said step of triggering a warning includes inducing a physically perceptible stimulation of the patient.

12. The method of claim 1 and further including the step of periodically automatically telemetering some or all of the data collected and calculated in steps (a) through (e) to a receiver external to said patient.

13. A method for monitoring the progression of the disease state of a patient comprising the steps of:

(a) sensing a pulse amplitude signal indicative of cardiac contractions of said patient'"'"'s heart;

(b) calculating a measure of autonomic tone based on amplitude variations of said sensed pulse amplitude signal;

(c) repeating steps (a) and (b) to acquire a plurality of autonomic tone measures;

(d) analyzing said plurality of autonomic tone measures to provide an indication of the progression of the disease state of said patient.

14. The method of claim 13 wherein said measure of autonomic tone is based on a number of said sensed pulse amplitude signals occurring in each of a plurality of predetermined counting intervals.

15. The method of claim 13 wherein said pulse amplitude signal is a measure of arteria pulse.

16. The method of claim 15 wherein said measure of said arterial pulse is a vascular plethysmography signal.

17. The method of claim 13 wherein said step of sensing a pulse amplitude signal is performed using ultrasound.