Dynamic Airflow Threshold Control for CPAP Pressure Adjustment
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Solution Overview
Problem
Existing CPAP devices either apply constant pressure, leading to discomfort, or adjust pressure after respiratory events occur, which can be inefficient and may trigger obstructive apneas during the transition from expiratory to inspiratory phases.
Innovation Solution
A respiratory assistance device that adjusts air pressure based on airflow measurements, increasing pressure during inspiratory phases when airflow reaches a minimum threshold and decreasing when it falls below, to prevent obstruction and improve comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant pressure is applied during both inspiratory and expiratory phases, then treatment efficiency is maintained, but patient comfort deteriorates due to excessive pressure during expiration
Solution Approach 1:
The patent implements dynamic pressure adjustment by introducing a minimum airflow threshold during the inspiratory phase. When measured airflow exceeds this threshold, the device maintains elevated treatment pressure; when airflow falls below the threshold, pressure is reduced. This dynamic response allows the system to adapt to actual respiratory needs, maintaining treatment effectiveness while reducing discomfort during phases when full pressure is not required.
Solution Approach 2:
The patent changes the pressure parameter based on airflow conditions by defining a minimum airflow threshold. The system transitions between two pressure states: a first pressure level when airflow exceeds the threshold and a second, lower pressure level when airflow falls below it. This parameter change strategy enables the device to optimize the balance between treatment efficiency and patient comfort by adjusting pressure according to actual respiratory flow characteristics.
2Object-affected harmful factors
If pressure is reduced during expiratory phase to improve comfort, then patient comfort improves, but treatment efficiency deteriorates because obstruction prevention pressure is not reached during transition
Solution Approach 1:
The patent applies preliminary action by establishing a minimum airflow threshold during the inspiratory phase before obstruction can occur. The system proactively maintains treatment pressure when airflow exceeds this threshold, ensuring that protective pressure is in place before the transition phase begins. This prevents obstructions from developing during the critical transition from expiration to inspiration, while still allowing pressure reduction during pure expiratory phases when the threshold is not met.
3Adaptability or versatility
If pressure adjustment is made after respiratory events occur, then automatic adaptation to respiratory conditions is achieved, but response time is delayed allowing obstructions to develop
Solution Approach 1:
The patent implements feedback control by continuously measuring airflow and comparing it against a predetermined minimum threshold during the inspiratory phase. Based on this real-time feedback, the device automatically adjusts pressure: maintaining treatment pressure when airflow exceeds the threshold and reducing pressure when it falls below. This closed-loop feedback system enables proactive adaptation to respiratory conditions without delay, as the system responds to airflow changes as they occur rather than reacting to detected events after they have already manifested.
Data Source
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Figure 3A~3B
Figure 4A
AI summary
The apparatus has a case with a turbine actuated in rotation by a motor for sending air below a pressure to a mask of a patient. A measuring unit measures an air flow and electronics having memory for controlling rotation of the turbine. An evaluating unit evaluates value of a base air flow and a maximal air flow for a patient. The apparatus delivers increasing and decreasing air pressures when the measured flow does not attain or attain a minimal air flow in breathing phase, respectively. The value of the minimal air flow is more than the base flow and lower than the maximal flow.