CPAP Pressure Reduction Triggered by Peak-Flow Decline
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Solution Overview
Problem
Existing CPAP devices struggle to alleviate discomfort during respiration by maintaining treatment pressure until the flow rate changes from positive to negative, making exhalation difficult and inspiration challenging.
Innovation Solution
A CPAP device with a controller that initiates pressure reducing control when a decrease in flow rate by a predetermined ratio from the peak flow rate during inspiration is detected, and adjusts pressure to synchronize with the patient's respiratory cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If treatment pressure is maintained until the flow rate changes from positive to negative, then the airway remains open and apnea is suppressed, but exhalation becomes difficult and patient comfort deteriorates
Solution Approach 1:
The controller starts pressure reducing control before the flow rate changes from positive to negative, specifically when the flow rate decreases by a predetermined ratio or more from the peak flow rate in the inspiration period. This preliminary pressure reduction facilitates subsequent exhalation while maintaining apnea suppression effectiveness.
Solution Approach 2:
The pressure control strategy dynamically adjusts based on the respiratory cycle phase. Treatment pressure is maintained during inspiration to suppress apnea, then reduced before expiration begins to facilitate comfortable exhalation. This dynamic adjustment resolves the contradiction between maintaining airway openness and enabling easy exhalation.
2Ease of operation
If pressure reducing control is started early in the inspiration period, then exhalation comfort is improved, but inspiration becomes difficult and treatment effectiveness deteriorates
Solution Approach 1:
Pressure reduction is initiated at the optimal moment - when the flow rate decreases by a predetermined ratio from the peak flow rate in the inspiration period. This timing ensures inspiration is complete and effective, while preparing the system for comfortable exhalation that follows.
Solution Approach 2:
The controller continuously monitors the flow rate during the inspiration period and uses this feedback to determine the precise timing for pressure reduction. By detecting when the flow rate decreases by a predetermined ratio from the peak, the system automatically identifies the optimal transition point from inspiration to exhalation phase.
Data Source
AI summary
Provided is a medical device for supplying gas of positive pressure to an airway of a patient. The medical device includes a controller that controls supply pressure, and the controller starts pressure reducing control on the supply pressure of gas when a decrease of a flow rate of the gas by a predetermined value from a peak flow rate in an inspiration period of the patient is detected.