Hypopnea Detection Using Respiratory Flow Variance Ratios

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Solution Overview

Problem

Current hypopnea detection apparatuses exhibit clinician variability in scoring due to differences in detection criteria, leading to inconsistent identification of hypopnea events in patients with obstructive sleep apnea (OSA), which can result in inadequate treatment and adverse consequences.

Innovation Solution

A hypopnea detection apparatus utilizing a processor to determine short-term and long-term variances in respiratory flow data, comparing these measures to specific proportions to accurately identify hypopnea events and their severity, while preventing multiple scoring of common events through refractory periods, and classifying events as obstructive or central based on flow limitation measures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If automated apparatus use various detection criteria to identify hypopnea events, then detection capability is improved, but clinician variability and inconsistency in scoring increase

Engineering Contradiction:
Improvehypopnea detection accuracyVSAvoidscoring consistency
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by systematically varying detection thresholds (e.g., 30%, 50%, 70% reductions in respiratory flow) and time window parameters (e.g., 10-second, 30-second windows) to establish a standardized detection framework. This resolves the contradiction by providing multiple calibrated parameter sets that maintain detection sensitivity while ensuring consistent scoring across different clinical scenarios through predefined criteria.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamics by using adaptive detection algorithms that adjust detection parameters based on individual patient baseline respiratory patterns. The system dynamically modifies detection thresholds and time windows according to each patient's specific breathing characteristics, thereby maintaining high detection accuracy while achieving scoring consistency through personalized adaptive criteria rather than fixed universal thresholds.

Inventive Principle:
Principle #15Dynamics

2Productivity

If detection criteria are made more sensitive to identify all hypopnea events, then detection completeness is improved, but false positive detections increase

Engineering Contradiction:
Improvehypopnea event detection completenessVSAvoiddetection accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies segmentation by dividing the detection process into distinct stages: initial event detection using sensitive thresholds, followed by verification stages that apply additional criteria (duration confirmation, flow pattern analysis, arousal detection). This multi-stage segmented approach ensures complete detection of hypopnea events while filtering out false positives through progressive validation at each segment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements feedback mechanisms where detection results are continuously evaluated and used to adjust subsequent detection parameters. The system incorporates feedback loops that verify detected events against multiple criteria (duration, flow reduction percentage, associated arousals, oxygen desaturation) and provide corrective feedback to refine detection accuracy, thereby maintaining high detection completeness while minimizing false positives through iterative validation.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP2260762B1Devices for the detection of hypopnoea
Publication Date: 2020.08.26 RESMED PTY LTD
  • EP2260762B1 patent drawingFigure 1
  • EP2260762B1 patent drawingFigure 2
  • EP2260762B1 patent drawingFigure 3

AI summary

Automated methods provide hypopnea detection for determining a hypopnea event and/or a severity of a hypopnea event. In some embodiments, a calculated short-term variance of a measured respiratory flow signal are compared to first and second proportions of a calculated long-term variance of the measured flow signal. A detection of the hypopnea may be indicated if the first measure falls below and does not exceed a range of the first and second proportions during a first time period. In some embodiments, a hypopnea severity measure is determined by automated measuring of an area bounded by first and second crossings of a short-term measure of ventilation and a proportion of a long-term measure. The detection methodologies may be implemented for data analysis by a specific purpose computer, a detection device that measures a respiratory airflow or a respiratory treatment apparatus that provides a respiratory treatment regime based on the detected hypopneas.