Low Dead Space Liquid Trap for Sidestream Capnography
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Solution Overview
Problem
Sidestream capnography systems face challenges with liquid separation in low-flow applications due to high dead space in existing water traps, leading to inaccurate gas measurement and signal fidelity issues, which limits their use in patients with lower respiratory flow rates.
Innovation Solution
A low dead space liquid trap design featuring a separation chamber with a gas permeable membrane and a reservoir, where the membrane is angled across the channel to separate liquid from the gas sample, allowing gas to pass while impeding liquid flow, and a hydrophilic wick aids in liquid removal, minimizing dead space and maintaining accurate gas measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional water trap is used in sidestream capnography, then liquid can be separated from the gas sample, but the dead space volume is large leading to inaccurate gas measurement and signal fidelity issues
Solution Approach 1:
The water trap is divided into distinct functional zones: a separation chamber with a gas permeable membrane that allows gas passage while blocking liquid, and a reservoir for liquid collection. This segmentation enables the trap to maintain minimal dead space volume while effectively separating liquid from gas, thereby preserving measurement accuracy in low-flow applications
Solution Approach 2:
A gas permeable membrane is used as a thin film barrier in the separation chamber. This membrane allows gas molecules to pass through while blocking liquid, enabling the creation of a compact separation structure with minimal dead space volume that maintains reliable gas measurement capabilities
2Ease of operation
If the flow rate is reduced for non-intubated patients, then comfort is improved, but liquid separation becomes ineffective due to high dead space in existing traps
Solution Approach 1:
A hydrophobic wick material is introduced as an intermediary substance in the separation chamber. This wick acts as a mediator that preferentially absorbs and channels liquid away from the gas flow path while allowing gas to pass through, enabling effective liquid separation even at the low flow rates used for non-intubated patient comfort
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 effectively separates liquid from the gas sample, reducing dead space and maintaining accurate CO2 measurement and signal fidelity, enabling reliable sidestream monitoring in low-flow applications, such as with non-intubated patients.
Implementation Method 1
a gas permeable membrane extending across the channel such that a first portion of the membrane disposed at a top of the channel is located closer to the inlet than a second portion of the membrane disposed at a bottom of the channel
Implementation Method 2
a hydrophilic wick aids in liquid removal
Data Source
AI summary
A low dead space liquid trap includes: a tube, having an inlet, an outlet, and an aperture disposed between the inlet and the outlet at a bottom of the tube, wherein the tube defines a channel extending in a first direction between the inlet and the outlet, the channel having a cross section perpendicular to the first direction; a reservoir disposed beneath the aperture of the tube; and a gas permeable membrane extending across the channel at an angle greater than zero with respect to the cross section of the channel.