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

• US 10,856,752 B2
• Filed: 12/27/2011
• Issued: 12/08/2020
• Est. Priority Date: 12/28/2010
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: Banet, Matt, Henry, Isaac, Bernstein, Donald
• Primary Examiner(s): Bloch, Michael R
• Application Number:
  US13/338,235
• Publication Number:
  US 20140249440A1
• Time in Patent Office: 3,269 Days
• Field of Search: 600526
• 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 comprising at least two electrodes attached to the patient'"'"'s body and comprising an impedance circuit configured and arranged to measure trans-brachial electrovelocimetry (TBEV) waveform from the patient;

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

(c) processing the TBEV waveform and the optical signal using a processing component of the body-worn monitor, wherein the processing component is configured to receive the TBEV waveform and the optical signal and to perform the following processing steps;

(i) processing the TBEV waveform to determine (d(TBEV)dZ/dt), a first zero value in d(TBEV)dZ/dt indicating onset of a pulse in d(TBEV)dZ/dt representing opening of the patient'"'"'s aortic valve, a second zero value in d(TBEV)dZ/dt after onset of the pulse indicating closing of the patient'"'"'s aortic valve, and a d(TBEV)dZ/dt_max value;

(ii) processing the first zero value in d(TBEV)dZ/dt and the second zero value in d(TBEV)dZ/dt to determine a first systolic flow time (SFT) value;

(iii) collectively processing the (TBEV)dZ/dt_max value and the first SFT value to determine a first stroke volume (SV) value;

(iv) processing the optical signal to determine a second SFT value;

(v) collectively processing the (TBEV)dZ/dt_max value and the second SFT value to determine a second SV value;

(vi) collectively processing the first and second SV values to determine a third SV value; and

(vii) displaying the third SV value on a display device.

2. A method according to claim 1, further comprising measuring an electrocardiogram (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;

and

processing the ECG signal using the processing component of the body-worn monitor, wherein the processing component of the body-worn monitor is further configured to receive the ECG signal and to perform the following processing steps;

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

collectively processing HR and the first SV value to determine a first cardiac output (CO) value from the patient;

collectively processing HR and the second SV value to determine a second CO value from the patient;

collectively processing the first and second CO values to determine a third CO value; and

displaying the third CO value on the display device.

3. A method according to claim 1, wherein the impedance sensor is worn on the patient'"'"'s chest and the at least two electrodes are attached proximal to the patient'"'"'s brachium;

and the optical sensor is worn on one of the patient'"'"'s fingers.

4. The method of claim 1, wherein the impedance sensor comprises four electrodes attached proximal to the patient'"'"'s brachial artery.

5. The method of claim 1, wherein the optical probe is worn on one of the patient'"'"'s fingers.

6. The method of claim 1, wherein the optical probe is worn on the patient'"'"'s thumb.

7. The method of claim 1, wherein collectively processing the (TBEV)dZ/dt_max value and the first SFT value comprises determining a square root transform of (dZ/dt)_max/Z_o to produce a value and processing this value and the first SFT value to determine the first SV value.

8. The method of claim 1, wherein the optical signal is a photoplethysmogram (PPG).

9. The method of claim 8, wherein processing the optical signal to determine the second SFT value comprises processing the PPG to determine a dichrotic notch, and analyzing a time-dependent value associated with the dichrotic notch to determine the second SFT value.

10. The method of claim 1, wherein collectively processing the (TBEV)dZ/dt_max value and the first SFT value to determine the first SV value comprises using an equation:

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

12. The method of claim 11, wherein the impedance sensor is further configured to transmit a digital representation of the impedance signal through a cable to the body-worn monitor.

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

14. The method of claim 13, 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.

15. The method of claim 1, wherein processing the optical signal to determine the second SFT value comprises determining a pulse rate (PR) from the optical signal, and estimating the second SFT value from the PR.

16. The method of claim 15, wherein estimating the second SFT value comprises processing PR with an equation:

SFT=−

0.0017*PR+0.413, or a mathematical derivative of the equation.