Neck-Worn Sensor for Non-Invasive Cardiac Output Monitoring
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Solution Overview
Problem
Current methods for measuring cardiac output (CO) and stroke volume (SV) in congestive heart failure patients are invasive, inaccurate, and impractical for continuous, non-invasive monitoring, especially for ambulatory patients, due to the need for specialized operators and equipment.
Innovation Solution
A necklace-shaped sensor that combines miniaturized impedance-measuring and ECG systems to measure CO, SV, fluid levels, and other cardiac parameters, transmitting data wirelessly for remote analysis, with algorithms compensating for patient motion and activity to improve measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If implanted devices with impedance measurement (OptiVol/CorVue) are used to measure thoracic fluid, then fluid status can be monitored, but the device is invasive and requires surgical implantation
Solution Approach 1:
The patent extracts the impedance measurement function from the implanted pacemaker device and places it in an external wearable sensor. This allows the same physiological parameter (thoracic fluid status via impedance) to be measured without requiring surgical implantation, thus removing the harmful invasive aspect while preserving the measurement capability
Solution Approach 2:
The patent introduces external sensors as an intermediary between the patient's body and the measurement system. These sensors measure impedance through skin-contact electrodes and transmit data wirelessly, serving as a non-invasive mediator that achieves the same measurement goal without direct internal device placement
2Measurement precision
If Doppler/ultrasound is used to measure cardiac output and stroke volume, then accurate hemodynamic parameters can be obtained, but specialized operators and equipment are required making it impractical for continuous home monitoring
Solution Approach 1:
The patent implements self-service by integrating multiple measurement functions (impedance, ECG, accelerometry) into a single wearable device that automatically collects and processes data without requiring specialized operators. The device performs autonomous hemodynamic estimation using algorithms that process sensor data locally, enabling continuous monitoring by patients themselves at home
Solution Approach 2:
The patent merges impedance measurement, ECG recording, and motion sensing into a single integrated wearable system. This combination allows the device to differentiate between respiratory and cardiac impedance variations while compensating for motion artifacts, achieving accurate continuous hemodynamic monitoring without the need for complex separate equipment or specialized operators
3Ease of operation
If simple weight gain measurement is used to detect CHF, then it can be done at home, but it is not sensitive enough to detect early onset of heart failure
Solution Approach 1:
The patent changes the measurement parameter from gross weight change to electrical impedance variation. Impedance changes occur earlier and more sensitively than weight gain, allowing detection of fluid accumulation at the onset of heart failure. The system continuously monitors impedance and can detect trends before they manifest as measurable weight changes
4Adaptability or versatility
If multiple separate devices are used to monitor different cardiac parameters, then comprehensive data can be collected, but device complexity and patient compliance become problematic
Solution Approach 1:
The patent creates a universal wearable platform that performs multiple cardiac monitoring functions through a single device. The system simultaneously measures impedance (for fluid status and stroke volume), records ECG (for heart rate and rhythm), and tracks motion (for activity level and posture). This multi-functional approach eliminates the need for patients to wear or manage multiple separate devices, significantly improving compliance while maintaining comprehensive monitoring capability
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
Provides continuous, non-invasive, and accurate monitoring of CO, SV, and fluid levels, enabling early detection of congestive heart failure and guiding patient management through web-based reports, improving clinical insights and patient compliance.
Implementation Method 1
measures the impedance across a patient's thoracic cavity
Implementation Method 2
measures ECG waveforms generated by cardiac activity
Data Source
AI summary
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.