Segmental Cuff Plethysmography for Arterial Compliance Measurement
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Solution Overview
Problem
Current methods for measuring endothelial dysfunction and reactive hyperemia are limited in their ability to provide accurate, non-invasive assessments over the entire transmural pressure range, and lack a comprehensive approach to monitor treatment efficacy in cardiovascular diseases.
Innovation Solution
A method and apparatus combining segmental volume plethysmography and oscillometry to generate arterial compliance and pressure-area curves, using a mathematical function-calibrated cuff plethysmography system that measures cuff compliance during both inflation and deflation phases, allowing for the calculation of reactive hyperemia and endothelial dysfunction levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressurized cuff is used to measure reactivehyperemia, then blood flow can be occluded and measured, but the measurement cannot cover the entire transmural pressure range accurately
Solution Approach 1:
The system dynamically adjusts cuff pressure through controlled inflation and deflation phases, allowing measurements across the entire transmural pressure range. The cuff pressure transitions from baseline to occlusion level and back, enabling the system to capture blood flow characteristics at multiple pressure points rather than at a single fixed pressure.
Solution Approach 2:
The method changes the pressure parameter systematically by inflating the cuff to different peak pressures and maintaining occlusion for varying durations. This parameter variation allows measurement of reactive hyperemia across different transmural pressure conditions, improving both accuracy and range coverage.
2Productivity
If segmental cuff plethysmography is performed with rapid inflation and deflation, then measurement time is reduced, but the holding phase required for reactivehyperemia induction is insufficient
Solution Approach 1:
The measurement process uses periodic inflation and deflation cycles of the cuff. Each cycle includes a rapid inflation phase, a controlled holding phase at occlusion pressure, and a rapid deflation phase. This periodic action allows sufficient occlusion duration for reactivehyperemia induction while maintaining overall measurement efficiency through repeated cycles.
Solution Approach 2:
The system performs preliminary rapid inflation to reach occlusion pressure quickly, then transitions to a controlled holding phase. This preliminary action minimizes the time to achieve the required occlusion state, allowing the majority of measurement time to be dedicated to the holding phase where reactivehyperemia is induced and measured.
3Measurement precision
If cuff compliance is measured during both inflation and deflation phases, then arterial compliance curves can be generated accurately, but device complexity increases
Solution Approach 1:
The same cuff and transducer system performs multiple functions: measuring cuff compliance during inflation, measuring cuff compliance during deflation, and generating arterial compliance curves. This multi-functionality eliminates the need for separate measurement systems while achieving comprehensive arterial compliance assessment.
Solution Approach 2:
The system continuously measures cuff compliance throughout both inflation and deflation phases rather than taking discrete measurements. This continuous measurement approach generates complete pressure-area curves and arterial compliance curves without requiring separate measurement protocols, reducing overall system complexity while maintaining high accuracy.
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 accurate, non-invasive measurement of arterial compliance and blood flow waveforms over the entire transmural pressure range, effectively detecting endothelial dysfunction and monitoring treatment efficacy in cardiovascular diseases, including early prediction of vascular events and progression of related conditions.
Implementation Method 1
a pressurized cuff to determine pressure-area (P-A) curves
Implementation Method 2
Segmental volume plethysmography is performed by injecting a standard volume of air into a pneumatic cuff or cuffs placed at various levels along an extremity. Volume changes in the limb segment below the cuff are translated into pulsatile pressure that are detected by a transducer
Implementation Method 3
Volume changes in the limb segment below the cuff are translated into pulsatile pressure
Data Source
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AI summary
A method for measuring reactive hyperemia in a subject is disclosed. The method includes performing a first segmental cuff plethysmography to generate a baseline arterial compliance curve and/or a baseline pressure-area (P-A) curve, performing a second segmental cuff plethysmography to generate a hyperemic arterial compliance curve and/or a hyperemic P-A curve, and calculating an area between the baseline and the hyperemic curves. The size of the area can be used as an indication of endothelial dysfunction (ED) and ED-related diseases.