Blood Pressure Estimation via Pulse Wave Signal Correction
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Solution Overview
Problem
Current methods for continuously estimating blood pressure without a cuff are limited in accuracy due to variations in pulse wave signals caused by factors other than blood pressure, such as light intensity and user characteristics, making it difficult to accurately measure systolic and diastolic blood pressure.
Innovation Solution
An apparatus and method that utilize a pulse wave sensor to measure a first pulse wave signal, differentiate or integrate it to obtain a reference signal, correct the signal to obtain a second pulse wave signal, and estimate blood pressure by normalizing the amplitude and adjusting offsets based on predetermined reference points like mean arterial pressure, systolic, and diastolic blood pressure, using a processor to calculate blood pressure features and variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If pulse wave signal is used to estimate blood pressure without a cuff, then continuous monitoring capability is improved, but measurement precision deteriorates due to signal variations from non-blood pressure factors
Solution Approach 1:
The patent introduces a reference signal as an intermediary element to mediate between the raw pulse wave signal and the blood pressure estimation. The reference signal, obtained through differentiation or integration of the pulse wave signal, serves as a mediator that captures blood pressure-related variations while filtering out non-blood pressure factors. This intermediary reference signal enables continuous monitoring while maintaining measurement precision by providing a stable basis for comparison and correction.
Solution Approach 2:
The patent applies parameter changes by transforming the pulse wave signal through differentiation or integration to obtain the reference signal. This mathematical transformation changes the parameters of the signal (from amplitude-domain to derivative/integral-domain), thereby emphasizing blood pressure-related variations while suppressing variations caused by other factors such as light intensity or user characteristics. This parameter transformation resolves the contradiction by enabling precise blood pressure estimation from the transformed reference signal.
2Measurement precision
If amplitude normalization and offset adjustment are applied to correct pulse wave signal, then measurement precision is improved, but device complexity increases due to additional signal processing steps
Solution Approach 1:
The patent applies preliminary action by performing amplitude normalization and offset adjustment as pre-processing steps before blood pressure estimation. The reference signal is first obtained through differentiation or integration, then amplitude normalization is applied to standardize the signal scale, and offset adjustment is performed to correct baseline shifts. These preliminary corrections are executed before the final blood pressure calculation, thereby improving measurement precision while keeping the processing steps organized and manageable.
Solution Approach 2:
The patent implements self-service by using the pulse wave signal itself to generate the reference signal through differentiation or integration, without requiring external calibration devices or additional sensors. The signal processing operations (normalization and offset adjustment) are performed automatically on the acquired signal, enabling the system to self-correct for variations and improve precision without adding external complexity.
Data Source
AI summary
An apparatus for estimating blood pressure, includes a pulse wave sensor configured to measure a first pulse wave signal from a user, and a processor configured to differentiate or integrate the measured first pulse wave signal to obtain a reference signal, correct the measured first pulse wave signal, based on the obtained reference signal, to obtain a second pulse wave signal, and estimate the blood pressure, based on the obtained second pulse wave signal.