Non-invasive Microcirculation Assessment via Pulse Wave Arrival Time
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Solution Overview
Problem
Current methods for assessing endothelial function in the microvasculature are invasive, require expensive equipment or trained personnel, and are not suitable for determining microcirculation function, particularly in microvasculature such as arterioles and capillaries.
Innovation Solution
A non-invasive method involving the measurement of pulse wave arrival time as a function of applied pressure, which allows for the assessment of microcirculation function parameters by varying external pressure and analyzing the time delay between heart activity and pulse wave arrival in the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods (invasive procedures, venous occlusion plethysmography, nitroglycerine induced vasodilation) are used to assess endothelial function, then measurement precision is improved, but device complexity and ease of operation deteriorate due to requiring expensive equipment and highly trained personnel
Solution Approach 1:
The patent replaces complex mechanical measurement systems (plethysmography equipment, invasive catheters) with a photoplethysmography-based optical system. The PPG sensor detects blood volume changes optically, eliminating the need for expensive mechanical equipment while maintaining measurement capability for endothelial function assessment.
Solution Approach 2:
The patent uses photoplethysmography to create an optical copy or representation of blood flow dynamics. Instead of directly measuring pressure or flow with complex equipment, the PPG sensor captures light absorption changes that replicate blood volume variations, providing a simplified yet accurate measurement of vascular response.
2Measurement precision
If current methods (invasive procedures, drug administration) are used to assess endothelial function, then measurement precision is improved, but ease of operation deteriorates due to requiring highly trained personnel
Solution Approach 1:
The patent enables the measurement system to perform self-calibration and automated analysis. The PPG sensor automatically detects pulse wave characteristics and calculates endothelial function parameters without requiring manual intervention or expert interpretation, making the device easy to operate while maintaining precision.
Solution Approach 2:
The system incorporates automated feedback mechanisms where the PPG signal is continuously monitored and analyzed by embedded algorithms. The device automatically adjusts measurement parameters and provides real-time assessment of endothelial function, eliminating the need for trained personnel to interpret complex data manually.
3Measurement precision
If current methods are used to assess endothelial function in large arteries, then measurement precision is improved, but adaptability deteriorates as they are not suitable for microvasculature assessment
Solution Approach 1:
The patent applies local quality by using photoplethysmography specifically targeted at microvascular beds (fingertips, earlobes) where capillary networks are accessible. The PPG sensor detects blood volume changes at the microvascular level, enabling endothelial function assessment in arterioles and capillaries rather than only in large arteries.
Solution Approach 2:
The patent transitions from assessing endothelial function in large conduit arteries to evaluating microvascular endothelium by measuring PPG signals at peripheral sites. This dimensional shift allows detection of pulse wave characteristics and vascular response in the microcirculation, expanding adaptability to different vascular beds.
4Measurement precision
If invasive procedures are used to assess endothelial function, then measurement precision is improved, but object-affected harmful factors worsen due to patient discomfort and risk
Solution Approach 1:
The patent replaces invasive mechanical procedures (catheter insertion, pressure cuffs) with non-invasive optical measurement. The PPG sensor uses light to detect blood volume changes without penetrating the skin or requiring physical intrusion, eliminating patient discomfort and procedural risks while maintaining measurement precision.
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 method provides a user-friendly, non-invasive assessment of endothelial function in microvasculature, enabling early diagnosis of cardiovascular diseases without the need for expert analysis or expensive equipment, suitable for both healthy subjects and patients with conditions like diabetes or atherosclerosis.
Implementation Method 1
a plurality of photoplethysmography (PPG) sensors comprising a first PPG sensor and a second PPG sensor, each sensor being arranged to carry out measurements indicative of blood flow
Data Source
Figure 1a~2
Figure 3a~3c
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AI summary
The present invention provides a method (100) for assessing at least one parameter related to the microcirculation function of a person, said method comprising the steps of a) determining (101) an arrival time (AT) of a pulse wave, wherein the AT is the time between the onset of an activity of the heart that produces said pulse wave and the arrival of said pulse wave in a part of the body of said person; b) varying (102) an applied pressure (P) on said part of the body over time and determining said AT as a function of applied pressure and time; and c) assessing (103) said at least one parameter related to the microcirculation function based on said determination of AT and said AT as a function of applied pressure and time in steps a) and b). The present invention furhter provides a system (1) for assessing at least one parameter related to the microcirculation function of a person (2).