Cuffless Blood Pressure Estimation from Dorsal Vibration Signals
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Solution Overview
Problem
Existing methods for measuring blood pressure, such as using a cuff around the arm, constrain the user and are not suitable for continuous or easy measurement, especially for individuals with high blood pressure or heart disease.
Innovation Solution
A non-constraining method that utilizes biological signals captured from the dorsal body surface to estimate blood pressure by analyzing vibrations associated with blood flow rate changes, employing fluctuation analysis and correlation data to determine blood pressure without physical constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cuff is used to measure blood pressure around the arm, then measurement precision is improved, but ease of operation deteriorates due to body constraint requirements
Solution Approach 1:
The patent replaces the mechanical cuff-based blood pressure measurement system with a vibration-based sensing system. Vibration sensors detect vibrations from the dorsal body surface that correspond to blood flow changes, eliminating the need for mechanical cuff inflation and deflation. This substitution maintains measurement capability while removing the constraining mechanical element.
Solution Approach 2:
The patent introduces vibration signals from the dorsal body surface as an intermediary to measure blood pressure. Instead of directly measuring pressure with a cuff, the system detects vibrations caused by blood flow changes and processes these signals to estimate blood pressure. This intermediary approach enables non-contact, constraint-free measurement.
2Measurement precision
If a cuff is used to measure blood pressure, then measurement precision is improved, but loss of time increases due to repeated constraint and stabilization
Solution Approach 1:
The patent enables continuous blood pressure monitoring by continuously detecting vibrations from the dorsal body surface. Unlike intermittent cuff-based measurements that require repeated application and removal, the vibration-based system maintains continuous operation without interruption, eliminating time loss between measurements.
Solution Approach 2:
By replacing the mechanical cuff system with a continuous vibration sensing system, the patent eliminates the need to repeatedly constrain and stabilize the body for measurement. The vibration sensors continuously capture blood flow-related vibrations without requiring periodic reapplication of the measurement device.
3Ease of operation
If vibration signals from dorsal body surface are used to estimate blood pressure, then ease of operation is improved by removing body constraint, but measurement precision may deteriorate
Solution Approach 1:
The patent employs feedback mechanisms in the signal processing chain to enhance measurement precision. The vibration signals are continuously processed through filtering, feature extraction, and correlation analysis with reference waveforms. This feedback-based processing compensates for signal variations and improves the accuracy of blood pressure estimation from the vibration data.
Solution Approach 2:
The patent transforms the vibration signal parameters through various processing steps including frequency filtering, amplitude normalization, and temporal correlation analysis. By changing the parameters of the vibration signals and comparing them against reference patterns, the system extracts precise blood pressure information from the raw vibration data.
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
Enables continuous and easy estimation of blood pressure, allowing for non-invasive, continuous monitoring by analyzing vibrations from the dorsal body surface, reducing the need for repeated arm constraining measurements.
Implementation Method 1
captures vibration generated on the dorsal body surface of the upper body of a person and estimates the state of the person by analyzing the vibration. The vibration generated on the dorsal body surface of the upper body of a person is vibration propagated from a human body inner part such as the heart and the aorta
Implementation Method 2
a blood flow rate change accompanying a change in venous return and a change in myocardial contractile force causes a change in blood pressure. Vibration (in this specification, the term simply mentioned as 'vibration' includes sound (acoustic wave)) propagated to the dorsal body surface contains more information on the left ventricle
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(c)
AI summary
Blood pressure is estimated in a non-constraining manner continuously and in real time. The present invention is configured to analyze a biological signal collected from a person's dorsal part, capture vibration in the human body (in vivo vibration) ascribable to a blood flow rate change in a period from the ventricular filling period to the isovolumetric systole, and further capture the state of fluctuation of an index indicating the state of the in vivo vibration (index regarding fluctuation (fluctuation index)). This fluctuation index correlates with information on a person's condition, in particular, a person's blood pressure as described above. Therefore, according to the present invention, it is possible to easily estimate blood pressure, in particular, estimate whether the blood pressure is in a range indicating a normal-range blood pressure (diastolic blood pressure of less than 90 mmHg, systolic blood pressure of less than 140 mmHg) or in a range indicating a high blood pressure, only by having the person sit or lie supine on a vehicle seat, a chair for home, office, or other uses, sleeping equipment such as a bed, or the like provided with a biological signal measurement device that can measure a biological signal in a non-constraining manner, so as to make the biological signal measurement device contiguous with the person's dorsal part.