CPAP Flow Limitation Detection via Airflow Slope Analysis
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Solution Overview
Problem
Existing CPAP machines are unreliable in detecting flow limitation conditions, particularly when airflow waveforms do not exhibit well-defined plateaus, leading to missed detections and potential sleep-disordered breathing events.
Innovation Solution
A method involving the analysis of airflow waveform variance and duty cycle kinetics to detect flow limitations, where the algorithm calculates the average slope and variance within moving windows to identify flattened areas, and adjusts therapy pressure accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prior art flow limitation detection methods are used, then the device can detect flow limitation conditions, but the detection is unreliable and may miss conditions where airflow waveform does not exhibit well-defined plateaus
Solution Approach 1:
The patent changes the detection parameter from looking for well-defined plateaus in the airflow waveform to calculating the average slope over a window of samples. This parameter change allows detection of flow limitation even when traditional plateau patterns are not clearly visible, thereby improving both reliability and measurement precision of flow limitation detection.
Solution Approach 2:
The patent replaces the mechanical/visual inspection method of identifying plateaus in airflow waveforms with a computational algorithm that calculates average slope values. This substitution enables more reliable and precise detection by using mathematical computation rather than relying on characteristic waveform patterns that may not always be present.
2Ease of operation
If therapy pressure is lowered to minimize patient discomfort, then patient comfort is improved, but flow limitation conditions may develop leading to sleep-disordered breathing events
Solution Approach 1:
The patent implements a feedback mechanism where the detection of flow limitation conditions (through average slope calculation) triggers an automatic response to adjust therapy pressure. This feedback loop ensures that pressure is increased before sleep-disordered breathing events occur, maintaining both patient comfort and prevention reliability.
Solution Approach 2:
The patent performs preliminary detection of flow limitation conditions using the average slope method before actual sleep-disordered breathing events occur. By detecting the developing flow limitation early, the system can preemptively adjust pressure to prevent events, rather than reacting after events have already occurred.
Data Source
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AI summary
A feature implemented in a CPAP breathing therapy machine to determine if the patient is suffering from a flow limitation condition and if so, altering the operation of the CPAP machine to attempt to alleviate the condition.