BODY-WORN VITAL SIGN MONITOR

• US 20180146862A1
• Filed: 09/27/2017
• Published: 05/31/2018
• Est. Priority Date: 09/15/2009
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: MOON, Jim, VISSER, II, Henk, HUNT, Robert Kenneth, McCOMBIE, Devin, DHILLON, Marshal Singh, BANET, Matthew J.
• Granted Patent: US 10,342,438 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• 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 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• 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 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: H04L 1/0078 Avoidance of errors by organising the transmitted data in a format specifically designed to deal with errors, e.g. location forward error control, e.g. FEC, CRC H04L1/004; adaptive formatting H04L1/0006; mappings H04L27/00
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control

Abstract

The invention provides a body-worn monitor featuring a processing system that receives a digital data stream from an ECG system. A cable houses the ECG system at one terminal end, and plugs into the processing system, which is worn on the patient'"'"'s wrist like a conventional wristwatch. The ECG system features: i) a connecting portion connected to multiple electrodes worn by the patient; ii) a differential amplifier that receives electrical signals from each electrode and process them to generate an analog ECG waveform; iii) an analog-to-digital converter that converts the analog ECG waveform into a digital ECG waveform; and iv) a transceiver that transmits a digital data stream representing the digital ECG waveform (or information calculated from the waveform) through the cable and to the processing system. Different ECG systems, typically featuring three, five, or twelve electrodes, can be interchanged with one another.

Claims

1. A system for measuring a blood pressure value from a patient, comprising:

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

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

(c) a third sensor configured to generate a third time-dependent waveform indicative of pressure applied to a patient'"'"'s arm; and

(d) a processing component configured to be worn on the patient'"'"'s body and comprising a microprocessor and a serial transceiver, the processing component configured to;

(i) communicate with a microprocessor and serial transceiver comprised by the first sensor to receive a digitized version of the first time-dependent waveform;

(ii) communicate with a microprocessor and serial transceiver comprised by the third sensor to receive a digitized version of the third time-dependent waveform;

(iii) calculate a pulse transit time calculated using a time difference between time-dependent features in digitized versions of the first and second time-dependent waveforms;

(iv) calculate a calibration from at least one pulse transit time and a pressure value determined from a digitized version of the third time-dependent waveform; and

(v) calculate the blood pressure value from the pulse transit time and the calibration.

3. The system of claim 1, wherein the first sensor is an ECG sensor.

4. The system of claim 3, wherein the first time-dependent waveform is an ECG waveform.

5. The system of claim 3, wherein the second sensor is an optical sensor.

6. The system of claim 5, wherein the second time-dependent waveform is a PPG waveform.

7. The system of claim 6, wherein the optical sensor is configured to be worn around the patient'"'"'s finger.

8. The system of claim 7, wherein the optical sensor is configured to be worn around the patient'"'"'s thumb.

9. The system of claim 6, wherein the processor component is further configured to calculate a pulse transit time from a time difference separating a QRS complex in the ECG waveform and a foot of a PPG waveform.

10. The system of claim 6, wherein the second sensor comprises a first LED operating in the red spectral range, and a second LED operating in the infrared spectral range.

11. The system of claim 10, wherein the second sensor is configured to generate a first PPG waveform using radiation from the first LED operating in the red spectral range, and a second PPG waveform using radiation from the second LED operating in the infrared spectral range.

12. The system of claim 11, wherein the processing component is further configured to calculate a SpO2 value from the first and second PPG waveforms.

13. The system of claim 1, wherein the third sensor is an inflatable cuff connected to a pneumatic system.

14. The system of claim 13, wherein the processing component is further configured to calculate a calibration from a blood pressure value determined from the third time-dependent waveform.

15. The system of claim 14, wherein the processing component is further configured to calculate a calibration from a group of pulse transit times, wherein each pulse transit time in the group is measured when a different pressure is applied to the patient'"'"'s arm.

16. The system of claim 15, wherein the third time-dependent waveform is indicative of a pressure measured while the cuff is inflating.

17. The system of claim 16, wherein the processing component is further configured to calculate a relationship between pulse transit time and blood pressure to determine the calibration.

18. The system of claim 1, wherein the processing component is configured to connect to the pneumatic system with a cable configured to transmit serial data.

19. The system of claim 18, wherein the cable comprises no more than 5 conductors.

20. The system of claim 19, wherein the cable is terminated with a connector, and the processing component comprises an input port comprising a group of conductors configured to match conductors in the cable, the input port configured so that the connector can be inserted into and detached therefrom.

21. The system of claim 1, wherein the processing component is configured to be worn on the patient'"'"'s wrist.

2. A method for calculating blood pressure from a patient, comprising the following steps:

(a) generating a first digital waveform indicating an ECG signal with a first remote sensor;

(b) generating a second digital waveform indicating a pressure signal with a second remote sensor;

(c) generating an analog waveform indicating an optical signal with a third remote sensor;

(d) synchronizing the first digital waveform, the second digital waveform, and a digitized version of the analog waveform;

(e) determining a pulse transit time from the first digital waveform and a digitized version of the analog waveform following (d);

(f) determining a calibration from the first digital waveform, the second digital waveform, and a digitized version of the analog waveform following (d); and

(g) determining a blood pressure value from the calibration and a pulse transit time.