Variable Rise-Time CPAP for Upper Airway Obstruction
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Solution Overview
Problem
Non-invasive positive pressure mechanical ventilation often fails to adequately address upper airway obstruction, resistance, or instability, as increasing end-expiratory pressure can decrease patient comfort and may not sufficiently resolve flow limitations.
Innovation Solution
A method and apparatus that adjust the rise-time of air pressure from expiratory to inspiratory levels in response to detected upper airway obstruction, resistance, or instability, using a CPAP device with a variable rise time to maintain patient comfort and treat sleep disordered breathing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If end-expiratory pressure is increased to resolve upper airway obstruction, then airway patency is improved, but patient comfort deteriorates
Solution Approach 1:
The patent applies dynamics by making the rise-time parameter variable rather than fixed. The ventilator dynamically adjusts the rise-time based on detected upper airway conditions, allowing the system to adapt to changing patient needs. This resolves the contradiction by enabling the system to provide sufficient pressure support when needed while avoiding excessive pressure that would discomfort the patient.
Solution Approach 2:
The patent changes the parameter of rise-time from a static setting to a variable parameter that can be adjusted in response to detected airway conditions. By monitoring the shape of the inspiratory flow curve and detecting flattening indicative of obstruction, the system modifies the rise-time parameter to optimize both airway patency and patient comfort.
2Productivity
If end-expiratory pressure is increased to resolve flow limitation, then ventilation effectiveness is improved, but patient comfort deteriorates
Solution Approach 1:
The system dynamically adjusts the rise-time parameter based on real-time monitoring of respiratory flow patterns. When flow limitation is detected through analysis of the inspiratory flow curve shape, the ventilator modifies the rise-time to improve ventilation effectiveness without maintaining constantly elevated pressures that would reduce patient comfort.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the inspiratory flow curve and using this information to adjust the rise-time parameter. The feedback loop detects flattening of the flow curve indicative of flow limitation and responds by optimizing the pressure delivery timing, thereby improving ventilation effectiveness while avoiding unnecessary increases in end-expiratory pressure that would harm patient comfort.
3Stability of the object's composition
If rise-time is increased to reduce upper airway obstruction, then airway stability is improved, but response time to deliver pressure is slowed
Solution Approach 1:
The patent applies dynamics by making rise-time a variable parameter that adapts to detected airway conditions. Rather than using a fixed slow rise-time that would guarantee stability but reduce response speed, the system dynamically selects appropriate rise-time values based on real-time monitoring of flow curve characteristics, thereby achieving both stability and rapid response when needed.
Solution Approach 2:
The system changes the rise-time parameter based on detected airway obstruction patterns. When flattening of the inspiratory flow curve indicates upper airway instability, the rise-time is increased to improve airway stability. When obstruction is not present, the rise-time can be reduced to maintain faster pressure delivery speed, thus resolving the contradiction through conditional parameter adjustment.
Data Source
AI summary
A CPAP apparatus has a variable rise time (iii) from a base level of positive air pressure during expiration (EPAP) to a higher level during inspiration (IPAP). The rise time is adjusted in order to reduce obstruction, resistance or instability in the upper airway.