Body-worn system for continuous, noninvasive measurement of cardiac output, stroke volume, cardiac power, and blood pressure
First Claim
1. A system for measuring a stroke volume of a patient, comprising:
- an impedance sensor comprising at least two electrodes and an impedance circuit, the at least two electrodes configured to be positioned on the patient in the clavicle/brachial region, and the impedance circuit configured to receive and process signals from the at least two electrodes to measure a transbrachial electro-velocimetry (TBEV) signal from the patient;
an optical sensor configured to be positioned on a hand of the patient and comprising an optical probe and an optical circuit, the optical circuit configured to receive and process signals from the optical probe to measure at least one optical signal from the patient; and
a processing system configured to;
(i) be worn on the patient'"'"'s body;
(ii) operably connect to both the impedance sensor and the optical sensor;
(iii) receive the TBEV signal from the impedance sensor;
iv) receive the at least one optical signal from the optical sensor;
(v) process the TBEV signal to determine a time dependent derivative of the TBEV signal (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, a d(TBEV)dZ/dtmax value;
(vi) determine a first systolic flow time (SFT) value calculated using the first zero value in d(TBEV)dZ/dt and the second zero value in d(TBEV)dZ/dt;
(vii) collectively process d(TBEV)dZ/dtmax and the first SFT value to determine a first stroke volume (SV) value;
(viii) process the optical signal to determine a second SFT value;
(ix) collectively process d(TBEV)dZ/dtmax and the second SFT value to determine a second SV value;
(x) collectively process the first and second SV values to determine a third SV value; and
(xi) display the third SV value on a display device.
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Accused Products
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 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.
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Citations
15 Claims
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1. A system for measuring a stroke volume of a patient, comprising:
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an impedance sensor comprising at least two electrodes and an impedance circuit, the at least two electrodes configured to be positioned on the patient in the clavicle/brachial region, and the impedance circuit configured to receive and process signals from the at least two electrodes to measure a transbrachial electro-velocimetry (TBEV) signal from the patient; an optical sensor configured to be positioned on a hand of the patient and comprising an optical probe and an optical circuit, the optical circuit configured to receive and process signals from the optical probe to measure at least one optical signal from the patient; and a processing system configured to;
(i) be worn on the patient'"'"'s body;
(ii) operably connect to both the impedance sensor and the optical sensor;
(iii) receive the TBEV signal from the impedance sensor;
iv) receive the at least one optical signal from the optical sensor;
(v) process the TBEV signal to determine a time dependent derivative of the TBEV signal (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, a d(TBEV)dZ/dtmax value;
(vi) determine a first systolic flow time (SFT) value calculated using the first zero value in d(TBEV)dZ/dt and the second zero value in d(TBEV)dZ/dt;
(vii) collectively process d(TBEV)dZ/dtmax and the first SFT value to determine a first stroke volume (SV) value;
(viii) process the optical signal to determine a second SFT value;
(ix) collectively process d(TBEV)dZ/dtmax and the second SFT value to determine a second SV value;
(x) collectively process the first and second SV values to determine a third SV value; and
(xi) display the third SV value on a display device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification