Body-worn system for measuring continuous non-invasive blood pressure (cNIBP)

• US 9,668,656 B2
• Filed: 12/30/2009
• Issued: 06/06/2017
• Est. Priority Date: 06/12/2007
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: Banet, Matt, Dhillon, Marshal, McCombie, Devin
• Primary Examiner(s): WEARE, MEREDITH H
• Application Number:
  US12/650,392
• Publication Number:
  US 20100160797A1
• Time in Patent Office: 2,715 Days
• Field of Search: 600481, 600485, 600500-507
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02133 by using induced vibration of the blood vessel
• CPC Class Codes: A61B 5/0225 the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 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 5/1118 Determining activity level
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence

Abstract

The present invention provides a technique for continuous measurement of blood pressure based on pulse transit time and which does not require any external calibration. This technique, referred to herein as the ‘Composite Method’, is carried out with a body-worn monitor that measures blood pressure and other vital signs, and wirelessly transmits them to a remote monitor. A network of body-worn sensors, typically placed on the patient'"'"'s right arm and chest, connect to the body-worn monitor and measure time-dependent ECG, PPG, accelerometer, and pressure waveforms. The disposable sensors can include a cuff that features an inflatable bladder coupled to a pressure sensor, three or more electrical sensors (e.g. electrodes), three or more accelerometers, a temperature sensor, and an optical sensor (e.g., a light source and photodiode) attached to the patient'"'"'s thumb.

Claims

1. A system for measuring a vital sign value from a patient, comprising:

(a) a first sensor configured to generate a first time-dependent signal indicative of one or more contractile properties of the patient'"'"'s heart;

(b) a second sensor configured to generate a second time-dependent signal indicative of one or more contractile properties of the patient'"'"'s heart, the second sensor comprising a radiation source configured to irradiate a portion of the patient, and a detector configured to detect radiation emitted from the radiation source after it passes through the portion of the patient, the detector comprising at least two pixel elements, each configured to generate a unique pixel element signal;

(c) a motion sensor configured to generate a motion signal indicative of movement of a region of the patient to which the motion sensor is configured to be attached; and

(d) a processing component configured to be worn on the patient'"'"'s body, the processing component programmed to;

(i) analyze each unique pixel element signal generated by each pixel element and the motion signal by performing a correlation analysis between the motion signal and each unique pixel element signal to determine a motion correlation value for each unique pixel element signal;

(ii) based on the analysis in (i), select at least one unique pixel element signal having the lowest motion correlation value; and

(iii) analyze the selected pixel element signal from (ii) to determine a vital sign value.

2. The system of claim 1, wherein the multi-pixel detector comprises at least a 3×

3 array of pixels.

3. The system of claim 2, wherein each pixel in the array of pixels comprises a photodetector.

4. The system of claim 1, wherein the motion sensor is an accelerometer.

5. The system of claim 4, wherein the accelerometer is configured to generate a digital motion signal corresponding to each of the x, y, and z-axes.

6. The system of claim 1, wherein the first sensor comprises an electrocardiogram (ECG) circuit and at least two electrodes.

7. The system of claim 6, wherein the first time-dependent signal comprises an ECG signal.

8. The system of claim 7, wherein the selected pixel element signal comprises a photoplethysmograph (PPG) signal.

9. The system of claim 8, wherein the processing component is programmed to determine an onset point in a portion comprised by the PPG signal.

10. The system of claim 9, wherein the processing component is programmed to determine a QRS complex comprised by the ECG signal.

11. The system of claim 10, wherein the processing component is programmed to determine a time difference between the QRS complex and the onset point.

12. The system of claim 11, wherein the processing component is programmed to calculate a blood pressure value from the time difference.

13. The system of claim 6, wherein the first sensor is configured to be worn on the patient'"'"'s chest.

14. The system of claim 1, further comprising a transceiver configured to be worn on the patient'"'"'s arm that comprises the processing component.

15. The system of claim 14, wherein the transceiver comprises the motion sensor.

16. The system of claim 1, wherein the second sensor is comprised by a flexible patch configured to be worn on the patient'"'"'s forehead.