Cardiovascular Parameter Estimation Using Pulse Propagation Time
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Solution Overview
Problem
Current methods for estimating cardiovascular parameters such as cardiac output (CO) and stroke volume (SV) are either invasive, inaccurate, or require complex calibration, and existing non-invasive methods lack robustness and reliability due to noise in derivative measurements and reliance on empirical data.
Innovation Solution
The use of arterial pulse pressure propagation time and waveform statistical moments to estimate cardiovascular parameters, including vascular tone and compliance, through a multivariate regression model that incorporates anthropometric data and pressure-dependent compliance, allowing for continuous and minimally invasive monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive flow-measuring devices are used to determine cardiac output, then measurement accuracy is improved, but patient safety and ease of operation deteriorate due to catheterization risks
Solution Approach 1:
The patent replaces invasive mechanical flow-measuring devices with a non-invasive optical detection system. The system uses light absorption characteristics of hemoglobin to measure blood flow and cardiac output through optical signals detected at the skin surface, eliminating the need for catheterization while maintaining measurement capability
Solution Approach 2:
The patent introduces light as an intermediary medium to indirectly measure blood flow parameters. Instead of directly measuring flow with invasive devices, the system uses light absorption changes caused by blood volume variations as an intermediary indicator to derive cardiac output information non-invasively
2Productivity
If derivative measurements are used in non-invasive methods, then continuous monitoring capability is improved, but measurement reliability deteriorates due to noise sensitivity
Solution Approach 1:
The patent employs periodic pulsatile light emission synchronized with the cardiac cycle to track blood flow variations. By using periodic optical pulses rather than continuous measurement, the system achieves continuous monitoring while the periodic nature provides inherent noise filtering through temporal sampling at consistent cardiac phases
Solution Approach 2:
The patent creates an optical copy or model of the blood flow signal through light absorption patterns. Instead of directly measuring mechanical flow derivatives, the system generates an optical signal representation of blood volume changes that can be analyzed without differentiating noisy mechanical signals
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
This approach provides a robust and accurate estimation of CO and related parameters, reducing sensitivity to calibration errors and noise, enabling continuous monitoring with improved accuracy across various clinical conditions.
Implementation Method 1
determining a propagation time of the input signal
Data Source
AI summary
A method and apparatus for determining a cardiovascular parameter including receiving an input signal corresponding to an arterial blood pressure measurement over an interval that covers at least one cardiac cycle, determining a propagation time of the input signal, determining at least one statistical moment of the input signal, and determining an estimate of the cardiovascular parameter using the propagation time and the at least one statistical moment.