Search

US-12622642-B2 - Patch-based physiological sensor

US12622642B2US 12622642 B2US12622642 B2US 12622642B2US-12622642-B2

Abstract

A body-worn patch sensor for simultaneously measuring a blood pressure (BP), pulse oximetry (SpO2), and other vital signs and hemodynamic parameters from a patient featuring a sensing portion having a flexible housing that is worn entirely on the patient's chest and encloses a battery, wireless transmitter, and all the sensor's sensing and electronic components. It measures electrocardiogram (ECG), impedance plethysmogram (IPG), photoplethysmogram (PPG), and phonocardiogram (PCG) waveforms, and collectively processes these to determine the vital signs and hemodynamic parameters. The sensor that measures PPG waveforms also includes a heating element to increase perfusion of tissue on the chest.

Inventors

  • Marshal Dhillon
  • Mark DHILLON
  • Erik TANG
  • Lauren Nicole Miller HAYWARD
  • Matthew Banet
  • James MCCANNA

Assignees

  • BAXTER INTERNATIONAL INC.
  • BAXTER HEALTHCARE SA

Dates

Publication Date
20260512
Application Date
20200508

Claims (19)

  1. 1 . A sensor for measuring a photoplethysmogram (PPG) waveform, a phonocardiogram (PCG) waveform, an impedance plethysmogram (IPG) waveform, and an electrocardiogram (ECG) waveform from a patient's chest, the sensor comprising: a housing configured to be located on the patient's chest; a reflective optical sensor for measuring the PPG waveform; a digital microphone for measuring the PCG waveform; a buzzer disposed in the housing, adjacent to the digital microphone, configured to generate an acoustic sound at a known amplitude and frequency; a processor disposed within the housing; and a set of electrodes that attach the optical sensor and the digital microphone to the patient's chest, with the set of electrodes connected to an ECG sensor configured to measure the ECG waveform, wherein the set of electrodes is further attached to an IPG sensor, the IPG sensor configured to measure the IPG waveform, wherein the IPG sensor is configured to inject current into the patient's chest, and further configured to measure the current to determine the IPG waveform, wherein the digital microphone is configured to compare the acoustic sound generated by the buzzer with the PCG waveform to determine a quality of patient-sensor adhesion between the sensor and a surface of the patient's chest, and wherein the processor uses time-domain analysis and frequency-domain analysis of the IPG waveform and uses time-domain analysis and frequency-domain analysis of the PCG waveform to collectively determine one of a coughing event, a wheezing event, and an apnea event by identifying amplitude modulation in the IPG waveform.
  2. 2 . The sensor of claim 1 , wherein the IPG sensor is configured to inject current at multiple frequencies into the patient's chest, and further configured to measure the current at multiple frequencies to determine the IPG waveform at multiple frequencies.
  3. 3 . The sensor of claim 1 , wherein the IPG sensor is configured to inject current at a single frequency into the patient's chest, and further configured to measure the current at the single frequency to determine the IPG waveform at the single frequency.
  4. 4 . The sensor of claim 1 , wherein the reflective optical sensor further includes a heating element.
  5. 5 . The sensor of claim 4 , wherein the heating element comprises a resistive heater.
  6. 6 . The sensor of claim 5 , wherein the resistive heater is a flexible film.
  7. 7 . The sensor of claim 1 , wherein the housing is of solid, unitary construction.
  8. 8 . The sensor of claim 1 , wherein the set of electrodes is a single electrode patch.
  9. 9 . A sensor for measuring a photoplethysmogram (PPG) waveform, a phonocardiogram (PCG) waveform, an impedance plethysmogram (IPG) waveform, and an electrocardiogram (ECG) waveform from a patient's chest, the sensor comprising: a housing configured to be located on the patient's chest; a reflective optical sensor for measuring the PPG waveform; a digital microphone for measuring the PCG waveform; a buzzer disposed in the housing, adjacent to the digital microphone, configured to generate an acoustic sound at a known amplitude and frequency; a processor disposed within the housing; and a set of electrodes that attach the optical sensor and the digital microphone to the patient's chest, with the set of electrodes connected to an ECG sensor configured to measure the ECG waveform, wherein the set of electrodes is further attached to an IPG sensor, the IPG sensor configured to measure the IPG waveform, wherein the digital microphone is configured to compare the acoustic sound generated by the buzzer with the PCG waveform to determine a quality of patient-sensor adhesion between the sensor and a surface of the patient's chest, and wherein the processor uses time-domain analysis and frequency-domain analysis of the IPG waveform and uses time-domain analysis and frequency-domain analysis of the PCG waveform to collectively determine one of a coughing event, a wheezing event, and an apnea event by identifying amplitude modulation in the IPG waveform.
  10. 10 . The sensor of claim 9 , wherein the IPG waveform is one of time-domain bioimpedance waveform and a time-domain bioreactance waveform.
  11. 11 . The sensor of claim 9 , wherein the PCG waveform is a time-domain acoustic waveform.
  12. 12 . The sensor of claim 9 , wherein the IPG sensor is configured to inject current into the patient's chest, and further configured to measure the current to determine the IPG waveform.
  13. 13 . The sensor of claim 12 , wherein the IPG sensor is configured to inject current at multiple frequencies into the patient's chest, and further configured to measure the current at multiple frequencies to determine the IPG waveform at multiple frequencies.
  14. 14 . The sensor of claim 12 , wherein the IPG sensor is configured to inject current at a single frequency into the patient's chest, and further configured to measure the current at the single frequency to determine the IPG waveform at the single frequency.
  15. 15 . The sensor of claim 9 , wherein the reflective optical sensor further includes a heating element.
  16. 16 . The sensor of claim 15 , wherein the heating element comprises a resistive heater.
  17. 17 . The sensor of claim 16 , wherein the resistive heater is a flexible film.
  18. 18 . The sensor of claim 9 , wherein the housing is of solid, unitary construction.
  19. 19 . The sensor of claim 9 , wherein the set of electrodes is a single electrode patch.

Description

PRIORITY CLAIM This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/845,097 entitled PATCH-BASED PHYSIOLOGICAL SENSOR, filed on May 8, 2019, the entire contents of which are incorporated by reference and relied upon. FIELD OF THE INVENTION The invention relates to the use of systems that measure physiological parameters from patients located, e.g., in hospitals, clinics, and the home. BACKGROUND There are a number of physiological parameters that can be assessed by measuring biometric signals from a patient. Some signals, such as electrocardiogram (ECG), impedance plethysmogram (IPG), photoplethysmogram (PPG), and phonocardiogram (PCG) waveforms, are measured with sensors (e.g., electrodes, optics, microphones) that connect or attach directly to the patient's skin. Processing of these waveforms yields parameters such as heart rate (HR), heart rate variability (HRV), respiration rate (RR), pulse oximetry (SpO2), blood pressure (BP), stroke volume (SV), cardiac output (CO), and parameters related to thoracic impedance, such as thoracic fluid content (FLUIDS). Many physiological conditions can be identified from these parameters when they are obtained at a single point in time; others may require continuous assessment over long or short periods of time to identify trends in the parameters. In both instances, it is important to obtain the parameters consistently and with high repeatability and accuracy. Some devices that measure ECG waveforms are worn entirely on the patient's body. These devices often feature simple, patch-type systems that include both analog and digital electronics connected directly to underlying electrodes. Typically, these systems measure HR, HRV, RR, and, in some cases, posture, motion, and falls. Such devices are typically prescribed for relatively short periods of time, such as for a time period ranging from a few days to several weeks. They are typically wireless, and usually include technologies such as Bluetooth® transceivers to transmit information over a short range to a second device, which typically includes a cellular radio to transmit the information to a web-based system. Bioimpedance medical devices measure SV, CO, and FLUIDS by sensing and processing time-dependent ECG and IPG waveforms. Typically, these devices connect to patients through disposable electrodes adhered at various locations on a patient's body. Disposable electrodes that measure ECG and IPG waveforms are typically worn on the patient's chest or legs and include: i) a conductive hydrogel that contacts the patient; ii) a Ag/AgCl-coated eyelet that contacts the hydrogel; iii) a conductive metal post that connects the eyelet to a lead wire or cable extending from the device; and iv) an adhesive backing that adheres the electrode to the patient. Medical devices that measure BP, including systolic (SYS), diastolic (DIA), and mean (MAP) BP, typically use cuff-based techniques called oscillometry or auscultation, or pressure-sensitive catheters than are inserted in a patient's arterial system. Medical devices that measure SpO2 are typically optical sensors that clip onto a patient's finger or earlobes, or attach through an adhesive component to the patient's forehead. SUMMARY OF THE INVENTION The present invention relates to methods and systems to improve the monitoring of patients in hospitals, clinics, and the home. As described herein, patch sensors are provided that non-invasively measure vital signs such as HR, HRV, RR, SpO2, TEMP, and BP, along with complex hemodynamic parameters such as SV, CO, and FLUIDS. The patch sensor adheres to a patient's chest and continuously and non-invasively measures the above-mentioned parameters without cuffs and wires. In this way, it simplifies traditional protocols for taking such measurements, which typically involve multiple machines and can take several minutes to accomplish. The patch sensor wirelessly transmits information to an external gateway (e.g., tablet, smartphone, or non-mobile, plug-in system) which can integrate with existing hospital infrastructure and notification systems, such as a hospital electronic medical records (EMR) system. With such a system, caregivers can be alerted to changes in vital signs, and in response can quickly intervene to help deteriorating patients. The patch sensor can additionally monitor patients from locations outside the hospital. More particularly, the invention features a chest-worn patch sensor that measures the following parameters from a patient: HR, PR, SpO2, RR, BP, TEMP, FLUIDS, SV, CO, and a set of parameters sensitive to blood pressure and systemic vascular resistance called pulse arrival time (PAT) and vascular transit time (VTT). The patch sensor also includes a motion-detecting accelerometer, from which it can determine motion-related parameters such as posture, degree of motion, activity level, respiratory-induced heaving of the chest, and falls. Such parameters could deter