Multi-Point Pulse Wave Processing for Cuff-Free Blood Pressure
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Solution Overview
Problem
Existing methods for estimating blood pressure using pulse wave propagation are inaccurate when the distance between measurement points is short, leading to degraded accuracy.
Innovation Solution
An information processing apparatus that derives pulse wave propagation speed by performing signal processing on pulse wave signals sensed at three or more different positions on a body surface, using sensors like laser Doppler flowmetry or photoplethysmography, and calculates blood pressure based on this speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pulse wave signals are measured at only two regions, then the measurement method is simple, but the accuracy of blood pressure estimation significantly degrades when the distance between regions is short
Solution Approach 1:
The patent divides the pulse wave measurement into multiple discrete regions (three or more) along the arterial path, allowing the system to segment the propagation path into multiple intervals. This segmentation enables more reliable velocity calculations by avoiding short-distance measurements while maintaining a manageable measurement framework.
Solution Approach 2:
The patent transitions from measuring at two points to measuring at three or more points, adding an additional dimension to the measurement space. This dimensional expansion allows the system to select optimal measurement pairs and calculate multiple velocity values that can be averaged or compared to improve accuracy.
2Length of stationary object
If the distance between measurement regions is short, then the measurement setup is compact, but the period required for pulse wave propagation is shortened leading to degraded accuracy
Solution Approach 1:
The patent applies partial action by selectively using only certain pairs of measurement regions for velocity calculation. Among three or more regions, the system identifies and uses pairs with adequate distance separation, discarding or de-weighting pairs with insufficient distance, thus achieving accurate measurements without requiring all possible region combinations.
Solution Approach 2:
The patent changes the parameter of measurement region selection from fixed two-point measurement to variable multi-point measurement. The system dynamically selects which regions to use based on signal quality and distance criteria, allowing optimal adaptation to different physiological conditions and anatomical variations.
3Measurement precision
If multiple sensors are used to improve signal quality, then the accuracy of pulse wave detection improves, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-selecting the optimal subset of sensors and measurement pairs before performing velocity calculations. The system evaluates signal quality and distance criteria in advance, identifying which sensors and region pairs will provide the most reliable data, thereby reducing the effective number of sensors needed for the final calculation.
Solution Approach 2:
The patent extracts and uses only the most valuable subset of sensor data for velocity calculation. From multiple available sensors, the system identifies and extracts the specific pairs of regions that provide adequate distance separation and high signal quality, discarding redundant or low-quality measurements to maintain 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
The apparatus achieves high accuracy in estimating pulse wave propagation speed and blood pressure by stabilizing peak position estimation and signal quality, even with varying sensor quality, providing a reliable and cuff-free blood pressure measurement.
Implementation Method 1
using sensors like laser Doppler flowmetry or photoplethysmography
Implementation Method 2
using sensors like laser Doppler flowmetry or photoplethysmography
Data Source
AI summary
To derive a pulse wave propagation speed with higher accuracy. An information processing apparatus includes a calculation unit configured to derive a pulse wave propagation speed of a subject by performing signal processing together on pulse wave signals sensed at three or more different positions on a body surface of the subject.