BODY-WORN SYSTEM FOR CONTINUOUS, NONINVASIVE MEASUREMENT OF CARDIAC OUTPUT, STROKE VOLUME, CARDIAC POWER, AND BLOOD PRESSURE

• US 20140249440A1
• Filed: 12/27/2011
• Published: 09/04/2014
• Est. Priority Date: 12/28/2010
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Donald Bernstein, Matt Banet
• Inventors: BANET, Matt, HENRY, Isaac, BERNSTEIN, Donald
• Granted Patent: US 10,856,752 B2
• Time in Patent Office: Days
• US Class Current: 600/526
• CPC Class Codes: A61B 2562/04 Arrangements of multiple sensors of the same type
• CPC Class Codes: A61B 5/0008 Temperature signals
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• 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 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6833 : Adhesive patches
• CPC Class Codes: A61B 5/7239 : using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/725 : using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61B 5/746 : Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: G16H 40/67 : for remote operation

Abstract

The invention provides a system for measuring stroke volume (SV), cardiac output (CO), and cardiac power (CP) from a patient that features: 1) impedance sensor connected to at least two body-worn electrodes and including an impedance circuit that processes analog signals from the electrodes to measure an impedance signal (e.g. a TBEV waveform); 2) an ECG sensor connected to at least two chest-worn electrodes and including an ECG circuit that processes analog signals from the electrodes to measure and ECG signal; 3) an optical sensor connected to a body-worn optical probe and including an optical circuit that processes signals from the probe to measure at least one optical signal (e.g. a PPG waveform) from the patient; 4) a processing system, typically worn on the patient'"'"'s wrist and connected through a wired interface to the optical sensor, and through either a wired or wireless interface to the TBEV and ECG sensors.

Claims

1. A method for determining stroke volume from a patient using a body-worn monitor, comprising:

(a) measuring an impedance signal with an impedance sensor operably connected to the body-worn monitor, the impedance sensor connected to at least two electrodes attached to the patient'"'"'s body and comprising an impedance circuit;

(b) measuring an optical signal with an optical sensor operably connected to the body-worn monitor, the optical sensor connected to an optical probe worn on the patient'"'"'s body and comprising an optical circuit;

(c) processing the impedance signal to determine a value of (dZ/dt)_max;

(d) processing the optical signal to determine a value of SFT; and

(e) collectively processing (dZ/dt)_max and SFT to determine the stroke volume.

5. The method of claim 1, wherein the impedance signal is measured by at least two electrodes attached proximal to the patient'"'"'s brachial artery.

6. The method of claim 5, wherein the impedance signal is measured by four electrodes attached proximal to the patient'"'"'s brachial artery.

7. The method of claim 1, wherein the optical signal is measured with an optical probe worn on one of the patient'"'"'s fingers.

8. The method of claim 1, wherein the optical signal is measured with an optical probe worn on the patient'"'"'s thumb.

9. The method of claim 1, wherein the impedance signal is derivatized and analyzed to determine (dZ/dt)_max.

10. The method of claim 9, further comprising take a square root transform of (dZ/dt)_max/Z₀ and processing this value and SFT to determine the stroke volume.

11. The method of claim 1, wherein the optical signal is a PPG.

12. The method of claim 11, further comprising processing the PPG to determine a dichrotic notch, and analyzing a time-dependent value associated with the dichrotic notch to determine SFT.

13. The method of claim 1, further comprising processing (dZ/dt)_max and SFT to determine the stroke volume using the following equation or a mathematical derivative thereof:

14. The method of claim 1, further comprising processing (dZ/dt)_max and SFT to determine the stroke volume using the following equation or a mathematical derivative thereof:

15. The method of claim 1, wherein the impedance sensor is operably connected to the body-worn monitor through a wired interface.

16. The method of claim 15, wherein the impedance sensor is further configured to transmit a digital representation of the impedance signal through a cable to the body-worn monitor.

17. The method of claim 1, wherein the impedance sensor is operably connected to the body-worn monitor through a wireless interface.

18. The method of claim 17, wherein the impedance sensor is further configured to transmit a digital representation of the impedance signal through the wireless interface to the body-worn monitor.

19. The method of claim 1, further comprising processing the optical signal to determine a PR, and estimating SFT from the PR.

20. The method of claim 19, further comprising processing PR with the following equation, or a mathematical derivative thereof, to estimate SFT:

SFT=−

0.0017*PR+0.413.

2. A method for determining cardiac output from a patient using a body-worn monitor, comprising:

(a) measuring an impedance signal with an impedance sensor operably connected to the body-worn monitor, the impedance sensor connected to at least two electrodes attached to the patient'"'"'s body and comprising an impedance circuit;

(b) measuring an optical signal with an optical sensor operably connected to the body-worn monitor, the optical sensor connected to an optical probe worn on the patient'"'"'s body and comprising an optical circuit;

(c) measuring an ECG signal with an ECG sensor operably connected to the body-worn monitor, the ECG sensor connected to at least two electrodes attached to the patient'"'"'s body and comprising an ECG circuit;

(d) processing the impedance signal to determine a value of (dZ/dt)_max;

(e) processing the optical signal to determine a value of SFT;

(f) processing the ECG signal to determine a value of HR; and

(g) collectively processing (dZ/dt)_max, HR, and SFT to determine the cardiac output.

3. A method for determining stroke volume from a patient using a body-worn monitor, comprising:

(a) measuring a time-dependent impedance signal with an impedance sensor worn on the patient'"'"'s chest and operably connected to the body-worn monitor through a wireless interface, the impedance sensor connected to at least two electrodes attached proximal to the patient'"'"'s brachium and comprising an impedance circuit;

(b) measuring a time-dependent optical signal with an optical sensor operably connected to the body-worn monitor through a wired interface, the optical sensor connected to an optical probe worn on one of the patient'"'"'s fingers and comprising an optical circuit;

(c) processing the time-dependent impedance signal to determine a value of (dZ/dt)_max;

(d) processing the time-dependent optical signal to determine a value of SFT; and

(e) collectively processing (dZ/dt)_max and SFT to determine the stroke volume.

4. A method for determining stroke volume from a patient using a body-worn monitor, comprising:

(a) measuring an impedance signal with an impedance sensor operably connected to the body-worn monitor, the impedance sensor connected to at least two electrodes attached proximal to the patient'"'"'s brachium and comprising an impedance circuit;

(b) measuring an ECG signal with an ECG sensor operably connected to the body-worn monitor, the ECG sensor connected to at least two electrodes attached to the patient'"'"'s body and comprising an ECG circuit;

(c) processing the impedance signal to determine a value of (dZ/dt)_max;

(d) processing the ECG signal to determine a value of HR;

(e) processing the HR to estimate a value of SFT; and

(f) collectively processing (dZ/dt)_max and the estimated value of SFT to determine the stroke volume.