Blood Pressure Measurement Envelope Correction for Respiratory Variation
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Solution Overview
Problem
Existing blood pressure measurement methods, such as the oscillometric and K sound methods, are prone to errors due to slight variations in blood pressure caused by respiratory fluctuations, leading to decreased measurement accuracy without increasing the accuracy of cuff pressure measurement, which would otherwise raise costs and measurement time.
Innovation Solution
A blood pressure measurement apparatus and method that includes a cuff with a pressurizing pressure adjustment unit, pressure detection, pulse wave, and blood flow sound detection units, generating pulse wave and blood flow sound envelopes to determine periodic blood pressure variations, and correcting the pulse wave envelope to maintain measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the accuracy of measuring the pressure in the cuff is raised, then the measurement precision of blood pressure is improved, but the cost of the apparatus increases and the measurement time increases
Solution Approach 1:
The pulse wave envelope is corrected in advance based on the blood pressure variation determination result before final blood pressure calculation. This preliminary correction prevents measurement errors caused by respiratory variations, eliminating the need for repeated measurements and reducing overall measurement time while maintaining accuracy
Solution Approach 2:
The invention introduces an intermediary correction mechanism using blood flow sound envelope analysis to detect and compensate for respiratory-induced blood pressure variations. This intermediary step allows accurate blood pressure measurement without requiring higher precision pressure sensors, thus avoiding increased cost and measurement time
2Measurement precision
If the accuracy of measuring the pressure in the cuff is raised, then the measurement precision of blood pressure is improved, but the cost of the apparatus increases
Solution Approach 1:
The invention uses blood flow sound envelope analysis as an intermediary to detect respiratory variations and correct pulse wave envelope accordingly. This approach achieves accurate blood pressure measurement using existing pressure sensor precision, avoiding the need for expensive high-precision sensors while maintaining measurement accuracy
Solution Approach 2:
The invention replaces the need for high-precision mechanical pressure measurement with a signal processing approach. By analyzing pulse wave and blood flow sound envelopes and applying corrections based on detected blood pressure variations, the system achieves accurate measurement without relying on expensive high-precision pressure sensors
3Ease of operation
If the envelope is not corrected for blood pressure variations, then the measurement process is simpler, but the blood pressure measurement accuracy decreases
Solution Approach 1:
The system performs preliminary detection of blood pressure variations using blood flow sound envelope analysis before final blood pressure calculation. This preliminary detection enables targeted correction only when variations are detected, maintaining process simplicity while ensuring accuracy when needed
Solution Approach 2:
The invention implements a feedback mechanism where the blood pressure variation determination unit continuously monitors for respiratory variations during measurement. When variations are detected, the system automatically applies envelope correction; when not detected, the measurement proceeds without correction. This feedback-based approach maintains simplicity while ensuring accuracy
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 effectively prevents decreases in blood pressure measurement accuracy due to respiratory variations by correcting the pulse wave envelope, ensuring accurate blood pressure determination without increasing cuff pressure measurement accuracy, thus maintaining precision without elevated costs or prolonged measurement times.
Implementation Method 1
a pressure detection unit configured to detect pressure in the cuff during a period of changing the pressurizing pressure
Implementation Method 2
a pulse wave detection unit configured to detect pulse waves in a cuff pressure signal that is a signal output from the pressure detection unit, the pulse waves being pressure components superimposed on the pressurizing pressure in synchronization with the body's pulse
Implementation Method 3
a blood flow sound detection unit configured to detect blood flow sounds that occur during a period of changing the pressurizing pressure
Data Source
AI summary
A CPU detects pulse waves in a pressure signal of a cuff detected during a period of reducing pressure applied by the cuff to a measurement site and acquires blood flow sound signals corresponding to blood flow sounds occurring in the pressure reduction period. Then, data for a pulse wave envelope that associates the amplitude values of the detected pulse waves with the pressurizing pressures at the pulse wave generation times, and data for a blood flow sound envelope that associates the amplitude values of the blood flow sound signals with the pressurizing pressures at the blood flow sound generation times are generated, and the data for the pulse wave envelope and the data for the blood flow sound envelope are used to determine whether or not there is periodic variation in the blood pressure during the pressure reduction period.