Oral Nasal Cannula Manifold Gas Sampling Design
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Solution Overview
Problem
Existing oral/nasal cannula manifolds suffer from reduced accuracy in gas analysis due to flow restrictions and dead spaces, leading to diluted samples and degraded capnographic waveforms, as they mix oxygen delivery with exhaled breath sampling, causing curvature and void volumes that alter gas waveforms and reduce sampling fidelity.
Innovation Solution
The oral/nasal manifold design features straight, aligned passages without void volumes or curvatures, with a deflector/concentrator plate enhancing gas collection, ensuring direct opposition of nasal and oral gas pressures and minimal mixing with ambient gases, and is made from a flame retardant thermoplastic polymer for safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If prior art oral/nasal cannulas combine oxygen delivery with exhaled breath sampling, then both functions are integrated in one device, but gas waveforms are altered and sampling fidelity is reduced
Solution Approach 1:
The device is segmented into distinct functional zones: an oxygen delivery region and a breath sampling region. The sampling passage is separated from the oxygen delivery passage, allowing independent optimization of each function. This segmentation prevents oxygen flow from interfering with the exhaled breath waveform while maintaining both functions in a single integrated device.
Solution Approach 2:
The sampling function is extracted from the oxygen delivery pathway. A dedicated sampling passage is created that branches off from the main oxygen delivery channel, allowing exhaled breath to be diverted into the sampling stream without being mixed with delivered oxygen. This extraction preserves waveform fidelity while maintaining integrated device functionality.
2Device complexity
If prior art cannulas include connected adjacent or ancillary void volumes in passages, then device structure is simplified, but gas mixing occurs and analysis accuracy is reduced
Solution Approach 1:
Void volumes and dead spaces are extracted from the sampling passage design. The passage is configured with smooth, continuous geometry that eliminates pockets of stagnant gas. This ensures that only freshly exhaled breath reaches the sensor without being diluted by ambient gas trapped in void volumes, thereby maintaining sampling accuracy while keeping the structure relatively simple.
Solution Approach 2:
The sampling passage incorporates optimized curvature radii that promote laminar flow and prevent turbulence. Smooth curved transitions eliminate flow separation and dead zones that would create void volumes. The curved geometry is carefully designed to maintain flow velocity and direction, preventing gas mixing while avoiding sharp angles that would complicate manufacturing.
3Volume of moving object
If prior art cannulas have curved sections in passages, then device can be compact, but flow restriction occurs and waveform is altered
Solution Approach 1:
The sampling passage uses optimized curved sections with specific radius-to-diameter ratios that minimize flow resistance. The curvature is gentle enough to maintain laminar flow and prevent turbulence, which would distort the waveform. At the same time, the curves allow the device to bend and conform to patient anatomy, maintaining compact form factor without sacrificing waveform quality.
Solution Approach 2:
The passage geometry parameters are optimized to balance compactness and flow quality. Curvature radius, passage diameter, and length are carefully selected to minimize pressure drop and flow restriction. The parameters are tuned so that the device remains flexible and compact while maintaining sufficient flow velocity to prevent gas mixing and preserve capnographic waveform fidelity.
4Ease of operation
If oral collectors mix excessive external gases with orally exhaled gases, then sampling is easier, but reading accuracy is reduced
Solution Approach 1:
The oral sampling function is extracted and isolated from ambient gas sources. The oral passage is designed as a closed conduit that directs exhaled breath directly to the sensor without exposure to external gases. This extraction prevents contamination while maintaining ease of operation through proper positioning and sealing at the oral cavity interface.
Solution Approach 2:
The oral passage acts as an intermediary channel that transports exhaled gases from the oral cavity to the sensor without direct exposure to ambient air. The passage design includes sealing elements and positioning features that prevent external gas infiltration, ensuring that only exhaled breath reaches the measurement point while maintaining easy placement and operation.
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
This design provides optimal sampling and analysis of exhaled gases with improved waveform fidelity and accurate carbon dioxide measurement, reducing signal degradation and enhancing the quality of capnographic data by minimizing flow restrictions and ambient gas interference.
Implementation Method 1
a suction port which is dimensioned and adapted to be connected with a collection conduit to a suction device for capnographic analysis
Implementation Method 2
the opposed nasal and oral passages are connected with the conduit passage of the suction port without any adjacent connected dead or void volumes and without any curvatures in the respective passages. Accordingly, the pressure of the exhaled nasal and oral gases of the subject directly oppose each other
Data Source
AI summary
An oral/nasal cannula manifold gas sampling and oxygen delivering manifold for sampling exhaled breath of a subject and delivering supplemental oxygen, the cannula including a main body portion having a suction port which is connected with a collection tube to a suction device for sampling the exhaled breath of the subject. A nasal prong upwardly protrudes from the main body portion and is positioned for insertion into a nostril of the subject to collect nasally exhaled breath. An oral conduit passage is embedded in a deflector/concentrator plate that extends downwardly from the main body portion and is also provided with a passage with an elongate lateral opening positioned for placement near the mouth of the subject to collect orally exhaled breath of the subject. The conduit passages of the nasal and oral passages are connected to and aligned in the same plane whereby the opposed nasal and oral conduit passages are connected with the conduit passage of the suction port without any adjacent connected void volumes or dead spaces in any of the passages.