Body-worn system for continuous, noninvasive measurement of cardiac output, stroke volume, cardiac power, and blood pressure

• US 9,364,158 B2
• Filed: 12/28/2011
• Issued: 06/14/2016
• Est. Priority Date: 12/28/2010
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: Henry, Isaac, Banet, Matt, Bernstein, Donald
• Primary Examiner(s): Koharski, Christopher D
• Assistant Examiner(s): KIMBALL, JEREMIAH T
• Application Number:
  US13/338,247
• Publication Number:
  US 20140249441A1
• Time in Patent Office: 1,630 Days
• Field of Search: 600/526
• US Class Current: 1/1
• 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) an 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. The processing system analyzes the ECG, TBEV and optical signals to determine SV, and further analyzes SV and HR determined from an ECG sensor to determine CO.

Claims

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

measuring an electrocardiogram (ECG waveform from a first portion on the patient'"'"'s body with an ECG module comprising;

i) at least two electrodes; and

ii) an ECG circuit configured to process signals from the at least two ECG electrodes to generate the ECG waveform;

measuring a trans-brachial electro-velocimetry (TBEV) waveform from a second portion on the patient'"'"'s body with an impedance module comprising;

i) at least two impedance electrodes; and

ii) an impedance circuit configured to process signals from the at least two impedance electrodes to generate the TBEV waveform;

measuring a photoplethysmograph (PPG) waveform from a third portion on the patient'"'"'s body with an optical module comprising;

i) an optical probe; and

ii) an optical circuit configured to process signals from the optical probe to generate the PPG waveform;

processing the TBEV waveform to determine a (dZ/dt)max value;

determining a systolic flow time (SFT value by processing at least one of;

i) the PPG waveform;

ii) the TBEV waveform; and

iii) the ECG waveform; and

determining a stroke volume value by processing the SFT value and the (dZ/dt)max value.

3. The method of claim 1, wherein the at least two ECG electrodes are proximal to the patient'"'"'s chest.

4. The method of claim 1, wherein the at least two impedance electrodes are proximal to the patient'"'"'s brachium.

5. The method of claim 1, wherein the optical probe is proximal to the patient'"'"'s hand.

6. The method of claim 1, wherein the body-worn device further comprises an accelerometer module configured to measure a time-dependent motion waveform from a patient.

7. The method of claim 6, wherein the body-worn device further comprises a processor module configured to compare the time-dependent motion waveform or at least one value derived from the time-dependent motion waveform to determine a motion value.

8. The method of claim 7, wherein the processor module is further configured to compare the motion value to a pre-determined threshold value.

9. The method of claim 8, wherein the processor module is further configured to reject a stroke volume value if the motion value exceeds the pre-determined threshold value.

10. The method of claim 9, wherein the processor module is further configured to process the TBEV waveform only if the motion value is less than the pre-determined threshold value.

11. The method of claim 1, wherein the (dZ/dt)max value is a derivative value of the TBEV waveform.

12. The method of claim 11, wherein the quotient of a (dZ/dt)max value and a corresponding value for Z₀ are further processed by taking its square root and further processing this value and the SFT value to determine the stroke volume value.

13. The method of claim 1, wherein the PPG waveform is further processed to determine the dichrotic notch, and analyzing a time-dependent value associated with the dichotic notch to determine the SFT value.

14. The method of claim 1, wherein the ECG waveform is further processed to determine a heart rate (HR) value.

15. The method of claim 14, wherein the HR is processed to estimate a value of SFT.

16. The method of claim 1, wherein the impedance module is connected to the body-worn device through wired interface.

17. The method of claim 16, wherein the impedance module is further configured to transmit a digital representation of the TBEV waveform through a cable on the body-worn device.

18. The method of claim 1, wherein the ECG module is connected to the body-worn device through a wired interface.

19. The method of claim 18, wherein the ECG module is further configured to transmit a digital representation of the ECG waveform through a cable on the body-worn device.

20. The method of claim 1, wherein the optical module is further configured to connect to the body-worn device through a wired interface.

2. A method for determining stroke volume from a patient using a body-worn device, the method comprising:

measuring an ECG waveform from a patient'"'"'s chest with an ECG module comprising;

i) at least two electrodes; and

ii) an ECG circuit, the ECG circuit configured to process the ECG signal from the ECG electrodes;

measuring a TBEV waveform from a patient'"'"'s brachium with an impedance module comprising;

i) at least two impedance electrodes; and

ii) an impedance circuit, the impedance circuit configured to process the at least one impedance signal from the at least two impedance electrodes to generate the TBEV waveform;

measuring an optical signal from a patient'"'"'s hand with an optical module comprising;

i) an optical probe; and

ii) an optical circuit configured to process the optical signal from the optical probe to generator the PPG waveform;

processing the TBEV waveform to determine a (dZ/dt)max value;

determining a SFT value by processing at least one of;

i) the PPG waveform;

ii) the TBEV waveform; and

iii) the ECG waveform; and

determining a stroke volume value by processing the SFT value and the (dZ/dt)max value.