Electronic Sphygmomanometer Height Correction via Upper Arm Reference
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Solution Overview
Problem
Conventional sphygmomanometers face inaccuracies in blood pressure measurement when the measurement site is not at the same height as the heart, particularly when using sites like the ear, wrist, or finger, as they require special hardware to adjust for height differences.
Innovation Solution
An electronic sphygmomanometer design that includes a first cuff for the peripheral site and a second cuff for the upper arm, with a pressure detection unit and a measurement control unit to correct blood pressure values by matching the peripheral site's equilibrium pressure with the upper arm's equilibrium pressure, using arterial volume signals to maintain arterial volume constant and adjust cuff pressure accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a peripheral site (ear, wrist, finger) is used as the measurement site, then the sphygmomanometer can be used at sites where height adjustment is not possible, but measurement accuracy deteriorates due to height difference from the heart
Solution Approach 1:
The patent introduces an upper arm cuff as an intermediary measurement device. The upper arm cuff measures blood pressure at a site close to the heart (minimal height difference), and this measurement serves as a reference to correct the blood pressure value obtained from the peripheral site, thereby eliminating the accuracy deterioration caused by height difference
Solution Approach 2:
The patent uses the upper arm blood pressure measurement as a copy/reference of the ideal blood pressure value (close to heart level). This reference value is then used to correct the peripheral site measurement through calculation, allowing accurate blood pressure measurement at peripheral sites without requiring height adjustment
2Measurement precision
If a tube filled with liquid is used to connect the measurement site and heart position, then blood pressure correction becomes possible, but device complexity increases
Solution Approach 1:
The patent extracts the essential function of blood pressure correction from the complex tube-based system. Instead of using a physical tube filled with liquid to transmit and correct pressure, the patent separates the measurement into two independent cuff measurements and uses computational correction based on the upper arm measurement as reference
Solution Approach 2:
The patent replaces the mechanical tube-based pressure transmission system with an electronic/computational system. The correction is achieved through electronic pressure detection and computational algorithms rather than mechanical fluid transmission, significantly reducing device complexity
3Ease of operation
If the measurement site height is not adjusted to match the heart height, then ease of operation improves, but measurement accuracy deteriorates due to differential pressure
Solution Approach 1:
The patent performs a preliminary measurement at the upper arm (close to heart level) before or during the peripheral site measurement. This preliminary measurement establishes a reference value that is used to correct the final blood pressure reading, allowing the peripheral site to remain at any height without compromising accuracy
Solution Approach 2:
The patent implements a feedback mechanism where the upper arm blood pressure measurement provides feedback information about the ideal blood pressure value. This feedback is used to calculate and correct the peripheral site measurement, ensuring accuracy regardless of height difference
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 accurate blood pressure measurement without special hardware, even at non-adjustable sites like the ear, by correcting for height differences using the upper arm's equilibrium pressure, thereby reducing measurement errors caused by site height variations.
Implementation Method 1
a pressure detection unit for detecting a first cuff pressure signal representing a pressure of the first cuff and a second cuff pressure signal representing a pressure of the second cuff
Implementation Method 2
the measurement control unit carries out an arterial volume constant control based on the first arterial volume signal to continuously measure the blood pressure
Data Source
AI summary
In a sphygmomanometer for measuring blood pressure according to a volume compensation method, an upper arm V0 equivalent cuff pressure representing a cuff pressure in a state where an inner pressure and an outer pressure of an artery of an upper arm are in equilibrium is specified based on a cuff pressure signal of the upper arm. For example, the upper arm V0 equivalent cuff pressure is detected as an average blood pressure obtained from the cuff pressure signal of the upper arm. After a control target value and an initial cuff pressure in the volume compensation are detected, a difference between the initial cuff pressure and the upper arm V0 equivalent cuff pressure is calculated as a correction value, and the blood pressure value in the volume compensation method is corrected with the calculated correction value.