Blood Pressure Cuff Pressurization Control via Linear Pressure Transition

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Solution Overview

Problem

Existing blood pressure measuring apparatuses face challenges in accurately predicting the timing to stop or suppress cuff pressurization due to non-linear changes in internal pressure, leading to potential improper measurement or excessive pressurization, especially in subjects with high systolic blood pressure.

Innovation Solution

The apparatus controls the pressurizing/depressurizing section to maintain constant pressure inside the flow path, transitioning the cuff pressure from a transient to a steady state, allowing for precise prediction and control of the pressurization timing, thereby improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pressurizing operation is stopped or suppressed based on real-time pressure monitoring, then the risk of excessive pressurization is reduced, but the measurement accuracy deteriorates due to non-linear pressure changes making timing prediction difficult

Engineering Contradiction:

Improvepressurization control safetyVSAvoidblood pressure measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary pressurization to establish a linear pressure-change state before the actual measurement phase. This preliminary action creates favorable conditions (linear pressure progression) for subsequent accurate timing prediction and measurement, resolving the contradiction between safe pressurization control and measurement precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The pressurization process is divided into distinct periods: a preliminary pressurization period to establish linear pressure change, followed by a measurement period where timing can be accurately predicted. This periodic structure allows the system to maintain both safety through controlled pressurization phases and accuracy through predictable measurement timing.

Inventive Principle:

Principle #19Periodic action

2Reliability

If the pressurizing operation is stopped earlier to ensure safety, then excessive pressurization is prevented, but blood pressure of subjects with high systolic pressure cannot be measured properly

Engineering Contradiction:

Improvepressurization control safetyVSAvoidapplicability to different blood pressure ranges

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

By performing preliminary pressurization to establish a known linear pressure-rate relationship, the system can accurately predict when the target pressure will be reached regardless of the subject's blood pressure level. This enables safe yet adaptable pressurization that can accommodate both low and high systolic pressure subjects.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the actual pressure and compares it with the predicted pressure based on the linear rate. This feedback mechanism allows dynamic adjustment of the pressurization control, ensuring safety while maintaining the ability to measure across different blood pressure ranges by adapting the stop timing to actual conditions.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If the pressurizing operation continues longer to ensure measurement of high blood pressure subjects, then measurement coverage is improved, but excessive pressurization occurs

Engineering Contradiction:

Improveapplicability to different blood pressure rangesVSAvoidexcessive pressurization effect

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The preliminary pressurization phase establishes an accurate linear pressure-change model that enables precise prediction of when the target pressure will be reached. This eliminates the need to over-pressurize to ensure coverage of high blood pressure subjects, as the system can safely stop at the exact moment the measurement pressure is achieved.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces mechanical trial-and-error pressurization with a computational prediction approach. By calculating the expected pressure trajectory based on the linear rate established during preliminary pressurization, the system can determine the exact stop timing mathematically, eliminating excessive pressurization while ensuring coverage of all blood pressure ranges.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3324838B1Blood pressure measuring apparatus

Publication Date: 2023.10.18 NIHON KOHDEN CORP

Figure 1~2

AI summary

A pressurizing/depressurizing section (4) performs at least one of air feeding to a cuff (20) by way of an air way (3) and air discharging by way of the air way (3) to thereby increase or decrease an internal pressure of the cuff (20). A first controlling section (5) causes the pressurizing/depressurizing section (4) to initiate the air feeding while performing the air discharging to thereby cause the internal pressure to transit from a pressure transient state to a pressure steady state or from the pressure steady state to the pressure transient state. A determining section (6) determines whether the internal pressure has transited to the pressure steady state by way of the pressure transient state. A second controlling section (7) causes the pressurizing/depressurizing section (4) to suppress or stop the air discharging while continuing the air feeding, in accordance with determination made by the determining section (6).