Sealed Nasal Cannula Interface for Dead Space Flushing

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Solution Overview

Problem

Existing respiratory interfaces fail to effectively flush dead space and regulate expiratory pressure, leading to inefficiencies in delivering breathing gases and potential re-inhalation of expired gases.

Innovation Solution

A user interface comprising a non-sealing nasal cannula with prongs delivering breathing gases in excess of peak inspiratory flow requirements, coupled with a mask that forms a seal with the face to allow continuous flushing of dead spaces and regulate expiratory pressure through adjustable outlets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a non-sealing nasal cannula is used to deliver breathing gases, then the gases can be administered at greater temperature and humidity, but dead space cannot be effectively flushed leading to re-inhalation of expired gases

Engineering Contradiction:

Improvebreathing gas temperatureVSAvoidre-inhalation of expired gases

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The interface is segmented into a mask portion that seals with the face and a separate nasal cannula portion that delivers gas to the nares. This segmentation allows the mask to provide dead space flushing while the cannula maintains the temperature and humidity benefits of direct nasal delivery.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention merges the sealing function of a facial mask with the direct nasal delivery function of a non-sealing cannula into a single integrated interface system, combining the advantages of both approaches while eliminating their individual disadvantages.

Inventive Principle:

Principle #5Merging (Combining)

2Object-affected harmful factors

If a facial mask is used to seal with the user's face, then dead space can be flushed, but the gases cannot be delivered at optimal temperature and humidity

Engineering Contradiction:

Improvedead space flushingVSAvoidbreathing gas temperature

Core Design Contradiction:

Object-affected harmful factorsVSTemperature

Solution Approach 1:

Different portions of the interface have different functions: the mask portion provides sealing and dead space flushing, while the nasal cannula portion provides direct warm and humidified gas delivery to the nares. Each component is optimized for its specific local function.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If high flow rates are delivered through small diameter cannula, then oxygen concentration is elevated, but the cannula cannot flush dead space effectively

Engineering Contradiction:

Improveoxygen concentrationVSAvoiddead space flushing efficiency

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The solution adds a spatial dimension by extending the cannula length and incorporating multiple delivery sites along its length. This allows the system to maintain high flow rates for oxygen delivery while also achieving adequate dead space flushing through the extended geometry.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Device complexity

If expiratory pressure is not regulated, then the interface is simpler, but treatment efficacy for respiratory disorders is reduced

Engineering Contradiction:

Improveinterface complexityVSAvoidtreatment efficacy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The mask portion with its seal creates a closed system that allows for pressure regulation through feedback mechanisms. The seal enables the system to monitor and control expiratory pressure, ensuring treatment efficacy while maintaining reasonable system complexity.

Inventive Principle:

Principle #23Feedback

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 interface effectively reduces re-inhalation of expired gases by continuously flushing dead spaces with fresh gases, regulates expiratory pressure, and delivers gases at optimal temperature and humidity, improving treatment efficacy for respiratory disorders.

Implementation Method 1

the cannula configured to deliver breathing gases to the nares of a user at a flow rate exceeding the intended user's peak inspiratory flow requirements

Methodology Applied

Scientific EffectGas flow:

Implementation Method 2

the mask including a seal configured to seal with a user's face to allow the interface to be pressurised

Methodology Applied

Scientific EffectSealing:

Implementation Method 3

regulate expiratory pressure through adjustable outlets

Methodology Applied

Scientific EffectPressure regulation:

Implementation Method 4

the mask and the user's pharynx are flushed continuously with fresh breathing gases to reduce dead space

Methodology Applied

Scientific EffectGas flushing:

Implementation Method 5

breathing assistance systems may incorporate a humidifier for heating and humidifying the breathing gases prior to delivery to the user

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 6

heating and humidifying the breathing gases

Methodology Applied

Scientific EffectHumidifying:

Data Source

PatentEP4218874B1An interface

Publication Date: 2025.11.26 FISHER & PAYKEL HEALTHCARE LTD

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AI summary

A user interface comprising a non-sealing nasal cannula and a mask arranged about the nasal cannula, the mask including a seal configured to seal with a user's face to allow the interface to be pressurised, the cannula configured to deliver breathing gases to the nares of a user at a flow rate exceeding the intended user's peak inspiratory flow requirements so that the mask and the user's pharynx are flushed continuously with fresh breathing gases to reduce dead space.