Body-worn sensor for characterizing patients with heart failure

• US 10,314,509 B2
• Filed: 12/31/2013
• Issued: 06/11/2019
• Est. Priority Date: 12/31/2012
• Status: Active Grant

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: OtoSense, Inc. (Analog Devices, Inc.)
• Inventors: Banet, Matthew, Pede, Susan Meeks, Dhillon, Marshal Singh, Hunt, Kenneth Robert
• Primary Examiner(s): Behringer, Luther
• Application Number:
  US14/145,229
• Publication Number:
  US 20140187896A1
• Time in Patent Office: 1,988 Days
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/6822 Neck

Abstract

The invention provides a sensor for measuring both impedance and ECG waveforms that is configured to be worn around a patient'"'"'s neck. The sensor features 1) an ECG system that includes an analog ECG circuit, in electrical contact with at least two ECG electrodes, that generates an analog ECG waveform; and 2) an impedance system that includes an analog impedance circuit, in electrical contact with at least two (and typically four) impedance electrodes, that generates an analog impedance waveform. Also included in the neck-worn system are a digital processing system featuring a microprocessor, and an analog-to-digital converter. During a measurement, the digital processing system receives and processes the analog ECG and impedance waveforms to measure physiological information from the patient. Finally, a cable that drapes around the patient'"'"'s neck connects the ECG system, impedance system, and digital processing system.

Claims

1. A sensor worn on a patient'"'"'s torso for measuring fluid in a patient'"'"'s chest and blood pressure, comprising:

a flexible member comprising a first electrode and a second electrode integrated within a flat, flexible cable, the flexible member comprising sufficient length and width so that when draped across a torso of the patient, the first electrode adheres below a collarbone and on the torso on a left-hand side of the patient, and the second electrode adheres below a collarbone and on the torso on a right-hand side of the patient,

an impedance-measuring system, comprised by a first circuit board integrated within the flexible member and in electrical contact with the first electrode and the second electrode and worn on the patient'"'"'s torso, the impedance-measuring system configured to receive the electrical signals from the first and second electrodes and process them to determine a first impedance signal comprising a baseline that varies with fluid in the patient'"'"'s chest, and a second impedance signal comprising heartbeat-induced pulses measured directly from an upper portion of the patient'"'"'s chest; and

,

a data-processing system, comprised by a second circuit board integrated within the flexible member and in electrical contact with the impedance-measuring system and worn on the patient'"'"'s torso, the data-processing system operating a computer algorithm configured to process the first impedance signal to determine fluid in the patient'"'"'s chest, the second impedance signal to determine a transit time, and the transit time to determine blood pressure.

2. The sensor of claim 1, comprising at least four electrodes.

3. The sensor of claim 2, comprising a first current-injecting electrode, a second current-injecting electrode, and wherein the first electrode is a first voltage-measuring electrode, and the second electrode is a second voltage-measuring electrode.

4. The sensor of claim 3, wherein the flexible member comprises a first segment comprising the first current-injecting electrode and the first electrode, the first segment configured to contact a first portion of the patient'"'"'s chest below the patient'"'"'s collarbone, and a second segment comprising the second current-injecting electrode and the second electrode, the second segment configured to contact a second segment of the patient'"'"'s chest below the patient'"'"'s collarbone.

5. The sensor of claim 4, wherein the first segment comprises a first rigid member, and the second segment comprises a second rigid member, and both the first and second rigid members comprise connectors configured to connect to the first electrode, the second electrode, the first current-injecting electrode, and the second current-injecting electrode.

6. The sensor of claim 5, wherein the flexible member comprises a flexible, current-conducting member that connects the first electrode, the second electrode, the first current-injecting electrode, and the second current-injecting electrode to the impedance-measuring system.

7. The sensor of claim 6, wherein the impedance-measuring system is configured to receive electrical signals that are measured by the first and second electrodes and pass through the flexible, current-conducting member.

8. The sensor of claim 7, wherein the impedance-measuring system comprises a differential amplifier.

9. The sensor of claim 8, wherein the differential amplifier is configured to measure a time-dependent voltage indicating the product of electrical impedance in the patient'"'"'s chest and current injected by the first and second current-injecting electrodes.

10. The sensor of claim 9, wherein the differential amplifier is configured to measure a first time-dependent voltage indicating the first impedance signal.

11. The sensor of claim 10, wherein the data-processing system is configured to operate a first computer algorithm configured to process the first impedance signal to estimate the fluid levels in the patient'"'"'s chest.

12. The sensor of claim 10, wherein the data-processing system is further configured to operate a second computer algorithm configured to process the first impedance signal to estimate the patient'"'"'s respiration rate.

13. The sensor of claim 9, wherein the differential amplifier is configured to measure a second time-dependent voltage indicating the second impedance signal.

14. The sensor of claim 13, wherein the data-processing system is further configured to operate a second computer algorithm configured to process the second impedance signal to estimate the patient'"'"'s blood pressure.

15. The sensor of claim 13, wherein the data-processing system is further configured to operate a third computer algorithm configured to process the second impedance signal to estimate the patient'"'"'s cardiac output.

16. The sensor of claim 13, wherein the data-processing system is further configured to operate a fourth computer algorithm configured to process the second impedance signal to estimate the patient'"'"'s stroke volume.