Optical Pulse Wave Analysis for Non-Invasive Vital Sign Monitoring
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Solution Overview
Problem
Current methods for detecting conditions like hypertension, atrial fibrillation, and other cardiovascular diseases are often invasive, costly, or inconvenient, and fail to provide regular and accurate monitoring of vital signs such as heart rate, respiratory rate, and blood pressure, leading to delayed detection of these conditions.
Innovation Solution
A mobile device equipped with a light source and optical sensor performs pulse wave analysis to determine heart rate variability, respiratory rate variability, and blood pressure, using indices like root mean square of successive differences, Shannon Entropy, and Poincare Plot Analysis to accurately diagnose medical conditions without the need for additional peripheral devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods (sphygmomanometer, invasive sensors) are used to measure blood pressure and heart rate, then measurement precision is improved, but ease of operation and ease of manufacture deteriorate due to invasiveness, cost, and complexity
Solution Approach 1:
The patent replaces traditional mechanical blood pressure measurement systems (sphygmomanometer with mercury column or inflatable cuff) with an optical measurement system using a light source and photodetector. The system measures pulse wave characteristics through optical absorption changes in blood vessels, eliminating the need for mechanical inflation and manual reading, thereby improving ease of operation while maintaining measurement capability
Solution Approach 2:
The patent introduces pulse wave analysis as an intermediary measurement approach. Instead of directly measuring blood pressure through mechanical means, the system measures pulse wave velocity and characteristics (time delay between initial upstroke and peak) as intermediate parameters, which are then correlated to blood pressure values. This indirect measurement method enables non-invasive, continuous monitoring
2Measurement precision
If traditional methods are used to detect atrial fibrillation and other conditions, then detection accuracy is improved through detailed analysis, but device complexity and cost increase
Solution Approach 1:
The patent creates a universal monitoring system where a single optical sensor setup serves multiple diagnostic functions. The same light source and photodetector arrangement used for blood pressure measurement also captures pulse wave data for detecting atrial fibrillation, calculating heart rate variability, and assessing vascular stiffness. This multi-functionality reduces device complexity and cost compared to dedicated systems for each measurement type
Solution Approach 2:
The patent segments the pulse wave signal into distinct characteristic points (initial upstroke, peak, dicrotic notch) for separate analysis. By identifying and measuring specific temporal and amplitude characteristics at different segments of the pulse wave, the system extracts multiple physiological parameters from a single continuous signal, reducing the need for multiple sensors or complex measurement setups
3Ease of operation
If sporadic and infrequent measurements are taken, then ease of operation is improved, but measurement precision and reliability deteriorate due to insufficient monitoring frequency
Solution Approach 1:
The patent enables continuous measurement action by implementing an automated optical sensing system that continuously monitors pulse wave characteristics without requiring repeated manual operations. The light source continuously illuminates the measurement site, and the photodetector continuously captures optical signal changes, providing uninterrupted data streams for reliable detection of transient conditions like paroxysmal atrial fibrillation
Solution Approach 2:
The patent implements periodic sampling of pulse wave characteristics at regular intervals to capture temporal variations in physiological parameters. By systematically measuring pulse wave velocity, amplitude, and morphology at defined time points and comparing across multiple cycles, the system reliably detects changes in blood pressure trends and rhythm abnormalities while maintaining operational simplicity
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 allows for non-invasive, efficient, and accurate monitoring of vital signs, improving the detection of conditions like atrial fibrillation and hypertension, with high sensitivity and specificity, and can be used continuously or at regular intervals, enhancing early detection and management of cardiovascular diseases.
Implementation Method 1
a means for providing pulse wave data representative of a heart beat of the human subject
Implementation Method 2
Pulse wave analysis can be employed in order to record and process different biological properties of a patient
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
An apparatus for An apparatus for determining a medical condition of a human subject, the apparatus comprising a control unit and a means for providing pulse wave data representative of a heart beat of the human subject. The control unit is configured to perform the steps of receiving the pulse wave data, selecting a portion of the pulse wave data indicative of a plurality of heart periods, determining a first index indicative of a heart rate variability based on the pulse wave data of the portion of the pulse wave data indicative of a plurality of heart periods, determining a second index indicative of a heart rate variability based on the pulse wave data of the portion of the pulse wave data indicative of a plurality of heart periods, the second index being different from the first index, and determining a medical condition of the subject based on the first and second indexes.