Photoplethysmograph and Bioimpedance Monitoring for Early HF Detection
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Solution Overview
Problem
Current methods for managing heart failure (HF) rely on unreliable patient-reported weight measurements, leading to suboptimal disease management and high hospitalization rates, with existing implantable devices being complex and underutilized.
Innovation Solution
A bioimpedance spectrometer system and photoplethysmograph system for non-invasive monitoring of physiologic parameters, including heart rate and fluid compartmentalization, to predict HF decompensation through wearable devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If patient self-reported daily weight is used to monitor HF, then monitoring can be performed, but the measurement is unreliable and patient compliance is very low
Solution Approach 1:
The patent replaces manual weight reporting with automated bioimpedance sensing. Electrical current is passed through the patient's body tissue, and impedance changes are measured automatically by the device, eliminating the need for manual weight measurement and reporting by the patient.
Solution Approach 2:
The device performs self-monitoring of fluid status through automated bioimpedance measurements. The system independently tracks impedance changes over time and generates alerts without requiring active patient participation in the measurement process, thereby improving both reliability and compliance.
2Reliability
If implantable devices are used to monitor physiologic parameters, then early detection of HF decompensation is possible, but the device complexity increases and requires surgical implantation
Solution Approach 1:
The patent replaces complex implantable electronic devices with a non-invasive bioimpedance measurement system. External electrodes and a measurement device are used instead of implanted sensors, eliminating surgical requirements while maintaining the ability to detect HF decompensation through impedance changes.
Solution Approach 2:
The system uses body tissue impedance as an intermediary parameter to indirectly measure fluid status and predict HF decompensation. Instead of directly measuring cardiac function or fluid volume, the device measures electrical impedance changes in the tissue, which correlate with fluid accumulation, providing a simpler non-invasive monitoring approach.
3Ease of operation
If body weight is used as a marker for cardiac decompensation, then monitoring is simple, but the marker is unreliable for detecting HF decompensation
Solution Approach 1:
The patent uses body tissue impedance as an intermediary measurement that correlates with fluid status. Electrical impedance changes in the tissue provide a more sensitive and specific indicator of cardiac decompensation compared to total body weight, while still maintaining simple non-invasive monitoring through external electrodes.
Solution Approach 2:
The system monitors changes in electrical impedance parameters over time rather than static weight measurements. By tracking impedance trends and rate of change, the device can detect early signs of fluid accumulation and HF decompensation with higher precision while keeping the monitoring process simple for the patient.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables early detection of HF decompensation, reducing hospitalizations and mortality by providing reliable, non-invasive, and user-friendly monitoring tools.
Implementation Method 1
A low-impedance or high-impedance current source circuit maintains a specified-range value of the alternating current (AC) current passing through the user's tissue such that the magnitude of a tissue impedance is equal to a differential voltage between two sense electrodes on the tissue divided by a known or measured current provided by the current source circuit
Implementation Method 2
A light-intensity sensor circuit converts the reflected LED light from the tissue into a second signal that is proportional to a reflected light intensity
Data Source
AI summary
In one aspect, a photoplethysmograph system to measure a user's heart rate includes one or more light-emitting diodes (LED) that provide a constantly-on light signal during a measurement period. The one or more light-emitting diodes are in optical contact with an epidermal surface of the user. The one or more light-emitting diodes emit a light signal into the tissue of the user, and wherein the tissue contains a pulsating blood flow. A light-intensity sensor circuit converts the reflected LED light from the tissue into a second signal that is proportional to a reflected light intensity. The second signal includes a voltage or current signal. A computer-processing module calculates the user's beat-to-beat heart rate from the second signal.