Observational Heart Failure Monitoring System

Abstract

Method and systems provide for reliable, convenient, and cost-effective personalized assessment of hemodynamic status in the ambulatory heart failure patient. The method and apparatus use pulse contour analysis of data obtained through observation of the patient for determination of hemodynamic status, and for determination of day-to-day changes in hemodynamic status. Observational assessment of the patient includes monitoring during activities of daily living including sleeping, sitting and standing. These activities create changes in venous return that are used to evaluate cardiac function or changes in cardiac function. The method and system infer body position by using position and motion information obtained by the system. Changes in cardiac function over time or due to changes in body pose are evaluated for the assessment of hemodynamic status, with a focus on changes resulting from fluid overload.

We claim: 
     
         1 . A method of assessing the volume status of an individual, comprising:
 (a) measuring a first pulse waveform of the individual with a noninvasive wearable sensor during a first observation period, where the first pulse waveform indicates a primary pulse wave and an incisura;   (b) detecting a positional change of the individual during an activity of daily living after the first observation period;   (c) measuring a second pulse waveform with the noninvasive wearable sensor during a second observation period after the positional change has been detected, where the second pulse waveform indicates a primary pulse wave and an incisura;   (d) determining a first duration of ventricular ejection from the first pulse waveform based on detection of the primary pulse wave and the incisura of the first waveform;   (e) determining a second duration of ventricular ejection from the second pulse waveform based on detection of the primary pulse wave and the incisura of the second pulse waveform;   (f) determining a measure of variation between the first and second durations of ventricular ejection; and   (g) assessing volume status of the individual from the measure of variation.   
     
     
         2 . A method of assessing the volume status of an individual, comprising:
 (a) measuring a first pulse waveform of the individual with a noninvasive wearable sensor during a first observation period, where the first pulse waveform indicates a primary pulse wave and an incisura;   (b) measuring a second pulse waveform with the noninvasive wearable sensor during a second observation period, where the second observation period is on a different day than the first observation period, where the second pulse waveform indicates a primary pulse wave and an incisura;   (d) determining a first duration of ventricular ejection from the first pulse waveform based on detection of the primary pulse wave and the incisura of the first waveform;   (e) determining a second duration of ventricular ejection from the second pulse waveform based on detection of the primary pulse wave and the incisura of the second pulse waveform;   (f) determining a measure of variation between the first and second durations of ventricular ejection; and   (g) assessing volume status of the individual from the measure of variation.   
     
     
         3 . An apparatus for assessing the intravascular volume status of an individual, comprising:
 (a) a noninvasive, pulse detection system configured to be worn by an individual and to measure a pulse waveform;   (b) a measurement control system configured to use the noninvasive pulse detection system to measure a first pulse waveform and a second pulse waveform, where the first pulse waveform and the second pulse waveform are from different cardiac cycles and where each of the first and second pulse waveforms indicates a primary pulse wave and an incisura; and   (c) an analysis system configured to determine a first duration of ventricular ejection from the first pulse waveform based on detection of the primary pulse wave and the incisura of the first pulse waveform, and to determine second duration of ventricular ejection from the second pulse waveform based on detection of the primary pulse wave and the incisura of the second pulse waveform, and to determine a measure of variation between the first and second durations of ventricular ejection to assess the intravascular volume status from the measure of variation.   
     
     
         4 . The apparatus of  claim 3 , further comprising:
 (d) a body position sensing system; and   (e) a communication system;   wherein the measurement control system is configured to measure the second pulse waveform after the body position sensing system indicates a change in body position after measurement of the first pulse waveform; and the communication system is configured to communicate an indication of intravascular volume status to a user of the apparatus.   
     
     
         5 . The system of  claim 4 , wherein subsystems (a), (b) and (c) are in a single housing. 
     
     
         6 . The system of  claim 4  wherein the single housing is a watch or a ring. 
     
     
         7 . The system of  claim 5  further comprising a sleep state determination system. 
     
     
         8 . The apparatus of  claim 3  wherein the pulse detection system is configured to avoid interference with activities of daily living. 
     
     
         9 . The apparatus of  claim 4  wherein the pulse detection system is configured to avoid interference with activities of daily living. 
     
     
         10 . The apparatus of  claim 5  wherein the pulse detection system is configured to avoid interference with activities of daily living. 
     
     
         11 . The apparatus of  claim 6  wherein the pulse detection system is configured to avoid interference with activities of daily living. 
     
     
         12 . The apparatus of  claim 7  wherein the pulse detection system is configured to avoid interference with activities of daily living.