Oxygen-capnography Mask with Internal Partition for CO2 Monitoring
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Solution Overview
Problem
Conventional face masks for delivering oxygen and monitoring exhaled carbon dioxide suffer from gas dilution and inaccurate CO2 concentration measurements due to the placement of CO2 sampling ports, which are often distant from the nose and mouth, prone to movement, and can cause re-breathing effects.
Innovation Solution
A face mask design featuring an internal partition wall that separates the oxygen delivery and CO2 sampling functions, with naris conduits positioned close to the nares to minimize gas interference and ensure accurate CO2 measurement, allowing for bi-directional fluid flow between the subject respiratory space and the oxygen reservoir space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the CO2 sampling port is placed distant from the subject's nose and mouth in conventional masks, then the mask structure is simpler, but the CO2 concentration measurement accuracy deteriorates due to gas dilution and flow dispersion
Solution Approach 1:
The mask internal space is segmented into two distinct spaces by an internal partition wall: a subject respiratory space (SRS) for CO2 sampling and a subject oxygen reservoir (SOR) space for oxygen delivery. This segmentation prevents mixing of oxygen and exhaled CO2, allowing accurate CO2 measurement while maintaining a relatively simple overall mask structure.
Solution Approach 2:
The internal partition wall acts as an intermediary barrier between the oxygen delivery system and the CO2 sampling system. It physically separates the two gas flows, preventing oxygen from diluting the exhaled CO2 in the sampling port while still allowing the mask to function as a unified device.
2Measurement precision
If the CO2 sampling port is positioned close to the subject's nares, then CO2 measurement accuracy improves, but the port becomes more prone to movement when the subject moves their head
Solution Approach 1:
The CO2 sampling port is merged with the internal partition wall structure itself, specifically positioned at the distal end of the naris conduit that is in direct communication with the subject's nares. This integration ensures the sampling port moves with the partition wall rather than independently, maintaining stable positioning relative to the subject's respiratory tract even during head movement.
3Device complexity
If the CO2 sampling port is placed within the stagnation space in conventional masks, then the mask structure is simpler, but re-breathing effect occurs causing CO2 concentration deviation from actual end-tidal values
Solution Approach 1:
The CO2 sampling function is extracted from the general mask stagnation space and placed into a dedicated subject respiratory space (SRS) that is specifically designed for capturing exhaled CO2. The naris conduit extends into the SRS to directly sample CO2 at the point of exhalation, eliminating the re-breathing effect that occurs when sampling from a general stagnation space.
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 prevents CO2 dilution during exhalation, enabling more accurate CO2 concentration measurements and maintaining measurement accuracy even when the mask slightly moves on the subject's face, regardless of breathing through the nose, mouth, or both.
Implementation Method 1
an internal partition wall that separates the oxygen delivery and CO2 sampling functions
Implementation Method 2
The naris conduits are configured such that they enable oxygen to flow from the SOR space to the SRS during inhalation while quickly expelling traces of CO2
Data Source
AI summary
A face mask for delivering oxygen to, and sampling carbon dioxide exhaled from, a subject includes a partition wall that divides the mask into a subject respiratory space that primarily contains carbon dioxide exhaled by the subject, and an oxygen reservoir space that primarily contain oxygen. The partition wall includes one or two holes to which naris conduits are respectively connected. The naris conduit are positioned in proximity to the subject's nares to closely obtain carbon dioxide samples. The naris conduits enable oxygen to flow from the oxygen reservoir space to the subject respiratory space during inhalation, while quickly expelling traces of CO2, and they configured such that exhaled CO2 quickly fills them up, during exhalation, and while expelling oxygen traces back to the oxygen reservoir space. During exhalation.