Cardiac Performance Determination Using Plethysmograph and ECG Signals
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Solution Overview
Problem
Existing methods for determining cardiac output are limited by the number of cardiac hemodynamic variables employed, leading to inaccurate estimates due to the exclusion of key determinants such as preload, afterload, and contractility.
Innovation Solution
The use of multiple cardiac function determinants associated with preload, afterload, and contractility, as represented by empirical relationships, to accurately calculate cardiac stroke volume and output, employing plethysmographic signals, ECG signals, and other physiological measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple cardiac function determinants are employed to accurately calculate cardiac stroke volume and output, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the complex task of cardiac output measurement into multiple independent cardiac function determinants (preload, afterload, contractility). Each determinant is measured or calculated separately using specific physiological parameters, and then combined through an empirical relationship to produce the final cardiac output value. This segmentation allows for improved accuracy by capturing multiple aspects of cardiac function while organizing the complexity into manageable, distinct components.
Solution Approach 2:
The patent employs a multi-functional approach where a single integrated system performs multiple functions: measuring various physiological parameters (blood pressure, flow velocity, volume), calculating different cardiac function determinants, and synthesizing them into comprehensive cardiac performance metrics. This universal system replaces multiple separate measurement devices and methods, achieving high measurement precision while consolidating device complexity into one coordinated platform.
2Reliability
If multiple cardiac function determinants are employed to accurately calculate cardiac stroke volume and output, then reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The patent implements self-service through automated calculation algorithms that automatically process the multiple cardiac function determinants and compute cardiac output without requiring manual intervention. The system autonomously integrates measurements of preload, afterload, and contractility using the empirical relationship, eliminating the need for operators to manually combine multiple complex measurements. This maintains high reliability through comprehensive data collection while improving ease of operation through automated synthesis.
Solution Approach 2:
The system incorporates feedback mechanisms where the measured physiological parameters continuously inform the calculation of cardiac function determinants. The empirical relationship acts as a feedback model that automatically adjusts the cardiac output calculation based on real-time measurements of preload, afterload, and contractility. This feedback loop ensures reliable determination of cardiac performance while the automated nature of the feedback process maintains operational simplicity.
Data Source
AI summary
Methods, associated algorithms, and systems for determining cardiac and/or cardiovascular performance from three measurements on a subject are presented, where two of the measurements are provided by plethysmographs and one measurement is provided by an electrocardiogram. The two plethysmographs are placed different distances from the subject's heart. Certain embodiments use the three measurements to calculate intermediate variables of a left ventricular ejection time and a pre-ejection period.