Respiratory Mask Bladder Pressure Offset for Seal Force Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing respiratory masks for conditions like obstructive sleep apnea, central sleep apnea, and respiratory insufficiency apply excessive force on the skin due to varying therapeutic pressures, causing discomfort and skin breakdown, as they lack effective mechanisms to counteract the distortion of headgear and facial tissues during pressure changes.
Innovation Solution
A mask system with a thin-walled, quasi-toroidal bladder that is pressurized to a positive offset pressure exceeding the instantaneous therapeutic pressure, using various sources such as weighted or spring-loaded pistons, centrifugal fans, or high impedance pumps with bypass valves to maintain a comfortable seal across a range of pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mask is tightened sufficiently to seal against the highest pressure used, then the seal is maintained at high pressure, but excessive force is applied to the skin causing discomfort and skin breakdown
Solution Approach 1:
The mask system employs dynamic adjustment mechanisms including inflatable bladders in the headgear that automatically inflate when mask pressure increases, and elastic elements that allow the mask to tighten and loosen in response to pressure changes. This dynamic behavior enables the mask to maintain adequate sealing force at high pressures while reducing force at lower pressures, preventing skin damage.
Solution Approach 2:
The system changes the sealing force parameter dynamically by varying the inflation pressure of bladders and adjusting elastic element tension based on the instantaneous mask pressure. This parameter adjustment allows the mask to apply appropriate sealing force only when needed, rather than maintaining constant high force throughout the respiratory cycle.
2Reliability
If the mask is tightened to seal at the highest pressure, then sealing is maintained across all pressures, but excess force is applied during lower pressure phases of respiration
Solution Approach 1:
The mask system incorporates feedback mechanisms where pressure sensors detect instantaneous mask pressure and automatically adjust the sealing force through inflatable bladders and elastic elements. This feedback loop ensures the mask maintains adequate seal only when pressure requires it, reducing excess force during low-pressure phases of respiration.
Solution Approach 2:
The sealing force is adjusted periodically in sync with the respiratory cycle, tightening during high-pressure inspiration phases and loosening during low-pressure expiration phases. This periodic adjustment maintains seal consistency during critical moments while minimizing excess force during non-critical phases.
3Stability of the object's composition
If a thick-walled non-compliant bladder is used for sealing, then structural stability is maintained, but great force is required to deform it to fit the patient's face
Solution Approach 1:
The bladder is designed with non-uniform wall thickness, featuring a thin-walled compliant region in the skin contact area that requires minimal force to deform for fitting, while thicker-walled regions maintain structural stability and pressure containment. This local quality variation allows the bladder to be easily fitted while maintaining integrity during use.
Solution Approach 2:
The bladder incorporates composite construction combining thin-walled compliant material in contact regions with thicker-walled structural material in containment regions. This composite approach integrates the benefits of both easy deformation and structural stability within a single component.
4Ease of operation
If a thin-walled compliant bladder is used for sealing, then ease of fitting is improved, but the bladder tends to slowly deflate during the night due to leakage and diffusion
Solution Approach 1:
The bladder uses composite material construction with thin-walled compliant sections for ease of fitting combined with thicker-walled sections that provide structural integrity and reduce leakage. This composite approach addresses both the ease of fitting requirement and the durability concern simultaneously.
Solution Approach 2:
The system incorporates pressure compensation mechanisms that proactively counteract the natural deflation tendency of thin-walled bladders by adjusting inflation pressure in response to pressure changes, preventing seal degradation over time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces mean skin pressure by up to 40% and maintains a comfortable seal, minimizing discomfort and skin irritation by dynamically adjusting the bladder pressure in response to changing therapeutic pressures, thereby improving mask fit and reducing leakage.
Implementation Method 1
pressurizing a bladder to a pressure which exceeds an instantaneous therapeutic pressure by a positive offset amount
Implementation Method 2
A greatly improved closed quasi-toroidal bladder is very thin walled and compliant in the skin contact region
Implementation Method 3
dynamically adjusting the bladder pressure in response to changing therapeutic pressures
Data Source
AI summary
A mask assembly includes a mask with an inflatable bladder. The internal pressure of the inflatable bladder can be set to be higher than the delivered therapeutic pressure. The pressure offset may be constant, or it may vary over the range of therapeutic pressures. Thus, the force necessary to maintain a contact seal between the mask and the patient can be reduced, thereby providing a system that is more comfortable to the patient, which increases patient compliance.