Video Pulse Wave Extraction for Cuffless Blood Pressure Inference
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Solution Overview
Problem
Conventional cuffless blood pressure measurement methods face challenges in accurately detecting pulse waves due to factors like makeup interference and limited skin exposure, making it difficult to infer blood pressure conveniently.
Innovation Solution
A device that captures moving images of a predetermined body part, such as a hand, at a high frame rate to detect pulse wave delay times between separated regions, converts the images to an uncompressed format, and reproduces them at a lower frame rate to extract pulse waves, using square-wave correlation filters to calculate pulse wave velocity and infer blood pressure information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If video of a face is used for pulse wave detection, then blood pressure can be estimated non-invasively, but accuracy deteriorates due to makeup interference and limited skin exposure
Solution Approach 1:
The patent applies local quality by selecting specific regions within the video frame that have optimal characteristics for pulse wave detection. Instead of using the entire face area, the system identifies and focuses on regions with adequate skin exposure and minimal makeup interference, thereby maintaining measurement accuracy while preserving the convenience of non-contact measurement.
2Measurement precision
If high frame rate video is captured to accurately detect pulse wave delay time, then measurement precision improves, but device complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by performing region selection and video processing optimization before the actual pulse wave detection. The system pre-identifies suitable skin regions and prepares processing parameters in advance, which simplifies the subsequent high-frame-rate analysis and reduces the computational burden on the device.
Solution Approach 2:
The patent extracts only the necessary components from the video data for pulse wave detection. By isolating specific skin regions and extracting only relevant temporal information from high-frame-rate video, the system maintains measurement precision while reducing the overall data processing requirements and device complexity.
3Productivity
If video data is processed in compressed format, then processing speed improves, but measurement precision deteriorates due to loss of image quality
Solution Approach 1:
The patent applies partial action by processing only the necessary portions of the video data at full resolution. Instead of decompressing and processing the entire video stream, the system selectively processes only the identified skin regions at high quality, while other areas are handled more efficiently, thereby maintaining both processing speed and measurement precision.
Data Source
AI summary
An object of the present invention is to provide a device for inferring blood pressure information that can infer blood pressure information conveniently. A device for inferring blood pressure information according to an embodiment of the present disclosure includes a moving-image acquisition unit configured to acquire moving images of a predetermined part of a living body captured at a first frame rate to detect a delay time between pulse waves in a first region and a second region separated by a predetermined distance in the predetermined part; a moving-image reproduction unit configured to reproduce the acquired moving images at a second frame rate lower than the first frame rate; a pulse wave extraction unit configured to extract a first pulse wave in the first region and a second pulse wave in the second region, based on the reproduced moving images; a pulse wave velocity calculation unit configured to calculate a pulse wave velocity from the predetermined distance and a time difference between peaks of the first pulse wave and the second pulse wave; a blood pressure information inference unit configured to infer blood pressure information, based on the calculated pulse wave velocity; and an output unit configured to output the inferred blood pressure information.