Prong-Free Cannula Gas Flow-Focusing for CO2 Sampling

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Solution Overview

Problem

Conventional nasal-oral cannulas with prongs for sampling exhaled CO2 and delivering oxygen are uncomfortable and cause irritation due to their design, which does not accommodate individual nasal geometries, leading to inefficient CO2 measurement and oxygen dilution.

Innovation Solution

A prong-free capnography cannula utilizing a gas flow-focusing device that employs the Coanda and Venturi effects to efficiently sample exhaled CO2 without mixing with propellant gases, using two fluid dynamics properties to enhance CO2 sampling and prevent dilution, and includes a cannula body with apertures for oxygen delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If nasal prongs are used for CO2 sampling, then CO2 measurement can be achieved, but patient comfort deteriorates and skin irritation occurs

Engineering Contradiction:

ImproveCO2 measurement accuracyVSAvoidskin irritation and discomfort

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent removes the nasal prongs from the cannula device entirely, extracting the harmful element that causes skin irritation while maintaining the CO2 sampling function through an alternative non-intrusive sampling mechanism that does not require insertion into the nasal cavity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary sampling chamber and gas flow path that mediates between the exhaled breath and the sampling system, allowing CO2 capture without direct contact with the patient's nasal mucosa, thus eliminating irritation while preserving measurement capability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If nasal prongs are pushed deep inside nostrils for CO2 sampling, then acceptable CO2 measurement is achieved, but oxygen dilution and gas dispersion increase

Engineering Contradiction:

ImproveCO2 measurement accuracyVSAvoidoxygen dilution of CO2 sample

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent segments the gas flow paths into distinct channels: one for oxygen delivery and another for CO2 sampling, preventing mixing of the two gas streams. This segmentation ensures that CO2 sampling does not result from oxygen dilution while maintaining accurate EtCO2 measurement

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes pneumatic principles with controlled gas flow rates and pressure differentials to direct exhaled breath through specific pathways to the sampling chamber, ensuring efficient CO2 capture without excessive oxygen mixing, thereby maintaining measurement accuracy while reducing dilution

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Ease of manufacture

If a single-size cannula design is used, then manufacturing is simplified, but adaptability to individual nasal geometries deteriorates

Engineering Contradiction:

Improvecannula manufacturing simplicityVSAvoidcompatibility with individual nasal geometries

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent incorporates adjustable or flexible components in the cannula design, such as adjustable positioning mechanisms or flexible tubing, that allow the device to adapt to different nasal geometries and patient anatomies while maintaining a relatively simple overall manufacturing process

Inventive Principle:

Principle #15Dynamics

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 provides accurate CO2 sampling with minimal dilution and comfortable patient use by effectively capturing exhaled CO2 and delivering oxygen without nasal prongs, ensuring reliable CO2 measurements and reduced patient discomfort.

Implementation Method 1

A prong-free capnography cannula utilizing a gas flow-focusing device that employs the Coanda and Venturi effects to efficiently sample exhaled CO2 without mixing with propellant gases

Methodology Applied

Scientific EffectCoanda effect: Coanda Effect

Implementation Method 2

A prong-free capnography cannula utilizing a gas flow-focusing device that employs the Coanda and Venturi effects to efficiently sample exhaled CO2 without mixing with propellant gases

Methodology Applied

Scientific EffectVenturi effect: Venturi Effect

Data Source

PatentUS10932692B2Prong-free cannula device for CO<sub>2 </sub>sampling and O<sub>2 </sub>delivery

Publication Date: 2021.03.02 ORIDION MEDICAL 1987

AI summary

A gas flow-focusing device (FFD) may include a cylindrical body that may include a funneling part to receive exhaled CO2-enriched air, and a CO2 sampling part. The CO2 sampling part and the funneling part are in fluid flow communication. The CO2 sampling part may include a CO2 sampling chamber to accept the CO2-enriched air, and a CO2 sampling tube to sample the CO2-enriched air. The funneling part and the CO2 sampling part may structurally form between them a ring-shaped gas chamber to contain a pressurized propellant gas, and a hollow channel in order to channel the pressurized propellant gas from the gas chamber to the CO2 sampling chamber. The gas chamber may include a gas intake opening through which propellant gas may fill the gas chamber. A prong-free cannula (PFC) may include two FFDs for sampling CO2, and a plurality of apertures for providing, there through, oxygen.