Pulse Wave Analyzer Respiratory Variation Accuracy

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Solution Overview

Problem

Existing apparatuses for analyzing respiratory variation in subjects using artificial respirators often result in low accuracy due to factors like spontaneous respiration, arrhythmia, and body movements, which affect the calculation of circulatory dynamics.

Innovation Solution

A pulse wave analyzer that acquires pulse waves, electrocardiograms, and respiration information, using a setting section to establish a selection criterion based on heart rate and respiration rate to select unit pulse waves and calculate respiratory variation, thereby improving accuracy by eliminating pulse waves with excessive amplitude variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If all pulse waves are used to calculate respiratory variation, then the calculation can be continuously performed, but the accuracy of the respiratory variation is low due to noise from spontaneous respiration, arrhythmia, and body movements

Engineering Contradiction:
Improveaccuracy of respiratory variationVSAvoidcomplexity of pulse wave selection
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-setting selection criteria based on the relationship between pulse wave amplitude and respiration information before calculating respiratory variation. The system determines thresholds for amplitude variation in advance, comparing each pulse wave against these pre-established criteria to filter out noisy signals. This approach prepares the filtering mechanism beforehand, enabling accurate respiratory variation calculation while avoiding the complexity of real-time adaptive threshold adjustment.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If pulse waves with large amplitude variation are included in the calculation, then more data is available for analysis, but the accuracy of circulatory dynamics assessment deteriorates due to noise from spontaneous respiration and arrhythmia

Engineering Contradiction:
Improvereliability of circulatory dynamics assessmentVSAvoidnumber of pulse waves used
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the selection criteria based on the relationship between pulse wave amplitude characteristics and respiration information. The system modifies the threshold parameters for amplitude variation according to the subject's respiratory state, ensuring that only pulse waves within acceptable amplitude ranges (indicative of stable circulatory conditions) are included in the respiratory variation calculation. This parameter adjustment maintains reliability while optimizing the quantity of usable pulse wave data.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3158927B1Pulse wave analyzer
Publication Date: 2021.06.30 NIHON KOHDEN CORP
  • EP3158927B1 patent drawingFigure 1
  • EP3158927B1 patent drawingFigure 2A~2C
  • EP3158927B1 patent drawingFigure 3

AI summary

A pulse wave analyzer includes: a pulse wave acquirer which is configured to acquire a pulse wave of a subject; an electrocardiogram acquirer which is configured to acquire an electrocardiogram of the subject; a respiration information acquirer which is configured to acquire respiration information of the subject; and an analyzing section which includes: a setting section which is configured to set a selection criterion based on the pulse wave or the electrocardiogram, and the respiration information; and a selecting section which is configured to select a pulse wave based on the selection criterion, wherein the analyzing section is configured to calculate a respiratory variation from the pulse wave which is selected by the selection section.