Blood Pressure Ratio Calculation via Fourier Transform

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Solution Overview

Problem

Existing methods for measuring blood pressure waveforms using tonometers struggle to accurately obtain absolute arterial pressure values due to cuff compression, limiting convenient and accurate evaluation of the cardiovascular system.

Innovation Solution

A blood pressure ratio calculation device and method that calculates the maximum-minimum blood pressure ratio from relative waveforms using Fourier transform, allowing derivation of absolute blood pressure waveforms for improved cardiovascular system evaluation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If correction using a cuff-measured blood pressure value is performed to obtain absolute arterial pressure from relative blood pressure waveform, then measurement precision of absolute pressure is improved, but ease of operation deteriorates due to cuff compression preventing tonometer measurement

Engineering Contradiction:

Improveabsolute arterial pressureVSAvoidtonometer measurement availability

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent introduces a photoelectric pulse wave as an intermediary measurement method that can be used during cuff compression when tonometer measurement is unavailable. This intermediary measurement allows continuous blood pressure waveform acquisition without interruption, resolving the contradiction between maintaining measurement precision and ensuring ease of operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical tonometer measurement method with photoelectric detection during cuff compression periods. This substitution allows the system to maintain continuous monitoring capability without requiring mechanical contact that would be blocked by the cuff, thus preserving both measurement precision and operational ease.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If only relative blood pressure waveform is used for cardiovascular evaluation, then ease of operation is maintained, but measurement precision of absolute pressure values deteriorates

Engineering Contradiction:

Improvecontinuous monitoringVSAvoidabsolute blood pressure values

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent performs preliminary correction of the blood pressure waveform by calculating the relationship between photoelectric pulse wave and tonometer waveform during periods when both measurements are available. This preliminary calibration enables subsequent conversion of photoelectric measurements to absolute pressure values, maintaining both operational ease and measurement precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses feedback from the relationship between photoelectric pulse wave characteristics and actual blood pressure values to continuously refine and correct the blood pressure waveform. This feedback mechanism ensures that the ease of continuous photoelectric monitoring does not compromise the precision of absolute pressure measurement.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If tonometer method is used to measure blood pressure waveform, then measurement precision of relative changes is improved, but ease of operation deteriorates during cuff compression

Engineering Contradiction:

Improverelative blood pressure changesVSAvoidmeasurement availability during correction

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent changes the measurement parameter from mechanical tonometer waveform to photoelectric pulse wave during cuff compression. This parameter change allows the system to maintain continuous monitoring capability while preserving the ability to capture blood pressure changes, as the photoelectric method is not affected by mechanical compression.

Inventive Principle:

Principle #35Parameter changes

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 convenient and accurate evaluation of the cardiovascular system by converting relative blood pressure waveforms into absolute values, enhancing the assessment of cardiac function and blood pressure dynamics.

Implementation Method 1

a spectrum generation unit for generating a relative blood pressure waveform spectrum by performing Fourier transform on the relative blood pressure waveform

Methodology Applied

Scientific EffectFourier transform:

Data Source

PatentUS10772513B2Blood pressure ratio calculation device, blood pressure ratio calculation method, blood pressure ratio calculation program, and recording medium recording said program

Publication Date: 2020.09.15 HAMAMATSU PHOTONICS KK

AI summary

A blood pressure ratio calculation device is a device for calculating a maximum-minimum blood pressure ratio corresponding to a ratio between a maximum blood pressure value and a minimum blood pressure value of an inspection target, and includes an input unit for inputting a relative blood pressure waveform corresponding to temporal change in relative blood pressure of the inspection target, a spectrum generation unit for generating a relative blood pressure waveform spectrum by performing Fourier transform on the relative blood pressure waveform, and an analysis unit for calculating the maximum-minimum blood pressure ratio on the basis of the relative blood pressure waveform spectrum.