Patient Interface Layering to Prevent CPAP Mask Condensation

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Solution Overview

Problem

Existing respiratory therapy systems, particularly CPAP therapy, suffer from condensation issues at the mask region due to humidified air cooling down and reaching dew point, leading to water condensation that can restrict airflow, form droplets, disrupt mask seals, and cause discomfort.

Innovation Solution

Incorporation of heating elements, insulating spaces, barrier layers, and breathable membranes in patient interfaces to reduce or prevent condensation, along with features like vents, hydrophobic and hydrophilic materials, and phase change materials to manage condensation effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If humidified air is used in CPAP therapy, then patient comfort is improved, but condensation forms in the mask region

Engineering Contradiction:
Improvedryness and irritationVSAvoidcondensation
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The mask is divided into multiple functional layers: an inner layer in contact with the patient's face, an intermediary chamber, and an outer layer. This segmentation allows the humidified air to be delivered through the inner layer while the intermediary chamber prevents condensation from reaching the patient's face.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

An intermediary chamber is introduced between the inner mask layer and the outer layer to act as a barrier. This intermediary structure captures condensation droplets formed by humidified air cooling, preventing them from dripping onto the patient's face while allowing the beneficial humidification effect to be maintained.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If heating elements are added to prevent condensation, then condensation is reduced, but device complexity increases

Engineering Contradiction:
ImprovecondensationVSAvoidmask structure
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The mask structure itself provides condensation management through its multi-layer design with an intermediary chamber. The geometry and material properties of the layers work together to prevent condensation accumulation without requiring external heating elements or active control systems, making the solution self-regulating and simpler.

Inventive Principle:
Principle #25Self-service

3Object-generated harmful factors

If the mask body is made thick for insulation, then condensation is prevented, but comfort and seal quality decrease

Engineering Contradiction:
ImprovecondensationVSAvoidcomfort and seal
Core Design Contradiction:
Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

Instead of using a single thick insulating layer that would compromise comfort and seal, the mask is segmented into multiple thin layers with an intermediary chamber. This allows insulation functionality to be distributed while maintaining direct contact between the inner layer and the patient's face for comfort and seal integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mask utilizes thin film structures for the inner and outer layers that provide necessary insulation while remaining flexible enough to conform to the patient's face. The thin film approach maintains seal quality and comfort while the intermediary chamber provides the condensation prevention function.

Inventive Principle:
Principle #30Flexible shells and thin films

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

Prevents condensation at the mask region, maintaining airflow and comfort by keeping the mask dry and reducing noise, thus enhancing patient compliance and therapy effectiveness.

Implementation Method 1

a water vapor breathable layer

Methodology Applied
Scientific EffectWater vapor breathability: Permeation

Implementation Method 2

The mask assemblies can incorporate heating elements (such as heating coils)

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

insulating spaces or barrier layers

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 4

phase change materials to manage condensation effectively

Methodology Applied
Scientific EffectPhase change: Phase Change

Implementation Method 5

The vent can comprise a hydrophobic material

Methodology Applied
Scientific EffectHydrophobicity: Hydrophobe

Data Source

PatentEP4397346B1Patient interfaces with condensation reducing or compensating arrangements
Publication Date: 2025.10.08 FISHER & PAYKEL HEALTHCARE LTD
  • EP4397346B1 patent drawingFigure 1~2
  • EP4397346B1 patent drawingFigure 3~5
  • EP4397346B1 patent drawingFigure 6~7

AI summary

Mask assemblies, breathing circuits and related components include configurations for reducing condensation within the mask and/or inhibiting or preventing condensation from coming into contact with a user of the mask. The mask assemblies can incorporate heating elements (such as heating coils), insulating spaces or barrier layers.