Oral Cannula Segmentation for ETCO2 Sampling Accuracy
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Solution Overview
Problem
Conventional nasal cannulas for capnography can lead to insufficient oxygen delivery and dilution of end-tidal carbon dioxide (ETCO2) samples due to uneven oxygen flow and interference with ETCO2 collection, especially during deep sedation, and may cause contamination from body fluids.
Innovation Solution
An oral cannula design with a fluted tip and hydrophobic filter to redirect bodily fluids and segregate oxygen from ETCO2, ensuring accurate sampling and preventing occlusions, along with a gas diverter to redirect oxygen flow and improve delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If oxygen is directed deep into the oral cavity to improve delivery, then oxygen treatment is enhanced, but ETCO2 collection is interfered with due to mixing and dilution
Solution Approach 1:
The oral cavity space is segmented into distinct zones: an anterior region for ETCO2 sampling and a posterior region for oxygen delivery. The cannula design creates separate flow paths where oxygen is directed to the back of the mouth while ETCO2 is sampled from the front, preventing mixing and allowing both functions to operate effectively simultaneously
Solution Approach 2:
A hydrophobic filter is introduced as an intermediary component in the ETCO2 sampling path. This filter selectively allows gases to pass while blocking body fluids, serving as a mediator that protects the sampling system from contamination without interfering with the oxygen delivery function
2Productivity
If higher oxygen flow rates are used during deep sedation, then oxygen treatment is improved, but ETCO2 sampling accuracy deteriorates due to dilution
Solution Approach 1:
The cannula design segments the oral cavity into functional zones that maintain separation even at high oxygen flow rates. The anterior sampling region captures ETCO2 before it mixes with the high-volume oxygen stream directed to the posterior region, ensuring accurate concentration measurements regardless of oxygen flow intensity
Solution Approach 2:
The hydrophobic filter acts as a protective intermediary that allows high oxygen flow rates to proceed uninterrupted while simultaneously protecting the ETCO2 sampling system from fluid contamination, enabling accurate measurements even during deep sedation with elevated oxygen demands
3Ease of operation
If the cannula is made flexible to improve comfort and fit, then ease of operation is improved, but structural stability deteriorates
Solution Approach 1:
The cannula employs a flexible construction with embedded reinforcement elements that allow the outer shell to conform to the patient's oral anatomy while maintaining internal lumen alignment. The flexible material enables comfort and adaptability without compromising the structural integrity needed for proper gas flow pathways
Solution Approach 2:
The cannula is segmented into multiple sections with varying degrees of flexibility and reinforcement. Critical portions requiring stability (such as the sampling and delivery lumens) have enhanced structural support, while other sections maintain flexibility for comfort and adaptation to different patient anatomies
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
Enhances oxygen delivery and reduces contamination, providing accurate ETCO2 sampling by redirecting oxygen flow and using a hydrophobic filter to protect the sampling lumen, thus improving the reliability of capnography monitoring.
Implementation Method 1
hydrophobic filter to redirect bodily fluids and segregate oxygen from ETCO2, ensuring accurate sampling and preventing occlusions
Data Source
AI summary
An oral cannula for placement within the oral cavity of a patient for delivery of a treatment gas and for collecting end-tidal carbon dioxide (ETCO2) includes a treatment gas delivery lumen including at least one aperture near a distal end of the treatment gas delivery lumen; an end-tidal CO2 sampling lumen. The cannula also includes a cap having (i) a gas diverter adapted for diverting at least a portion of the treatment gas and (ii) an end-tidal CO2 inlet including flutes and apertures there between that are in communication with the end-tidal CO2 sampling lumen. The oral cannula is adapted for custom bending or has a bend such that the oral cannula is insertable and retainable in a patient's mouth and functional for supplying a treatment gas and sampling gas exhaled by the patient.