In-line Aspirator Tester with Colorimetric Capnometer
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Solution Overview
Problem
Current methods for determining the correct placement of nasogastric (NG) tubes, such as pH testing, are unreliable due to false positives and negatives, which can lead to serious health consequences, especially when patients are on antacids or have reflux, as they do not accurately differentiate between stomach and lung fluids.
Innovation Solution
An in-line tester is used with an NG aspirator, featuring a hydrophobic liquid-stop device and colorimetric capnometer that detects carbon dioxide and stomach-related markers, providing a more reliable method for determining NG tube placement by sequentially testing gases and liquids, preventing false readings through a self-closing valve mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pH testing is used to determine NG tube placement, then the procedure is simple and quick, but the reliability of the test is poor due to false positives and negatives
Solution Approach 1:
The invention segments the verification process into multiple independent detection stages: first detecting carbon dioxide presence to identify gastric origin, then measuring pH as a secondary confirmation. This multi-stage segmentation allows each test to complement the other, reducing false positives and negatives while maintaining operational simplicity.
Solution Approach 2:
The in-line tester device performs multiple functions within a single integrated system: it detects carbon dioxide, measures pH, and provides visual indication of results. This multi-functionality allows the device to overcome the limitations of standalone pH testing by combining multiple verification methods without requiring separate procedures.
2Reliability
If multiple detection methods are combined to improve reliability, then the accuracy of NG tube placement determination improves, but the device complexity increases
Solution Approach 1:
The invention merges carbon dioxide detection and pH measurement capabilities into a single integrated in-line tester device that connects directly to the NG tube. By combining these detection methods in one device rather than using separate procedures, the system achieves high reliability while minimizing the complexity that would arise from multiple separate devices or procedures.
Solution Approach 2:
The device provides self-contained operation with all necessary detection components, power sources, and result indication mechanisms integrated within the single in-line tester unit. This self-service design eliminates the need for external equipment or complex multi-device setups, maintaining simplicity despite the advanced multi-parameter detection capabilities.
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 in-line tester significantly reduces false positives and negatives, ensuring accurate NG tube placement by combining carbon dioxide and stomach-related marker detection, thereby minimizing the risk of incorrect feeding and improving patient safety.
Implementation Method 1
a colorimetric capnometer downstream of the liquid-stop device and before the outlet. The colorimetric capnometer is adapted to change colour in the presence of carbon dioxide
Implementation Method 2
a first tester, for example in the form of a disc, which changes colour in the presence of a target substance
Implementation Method 3
a porous or perforated liquid-stop device, for example made from a hydrophobic material, which when dry enables the passage of gases from the inlet to the outlet, but when wetted by an aspirated liquid, prevents the passage of liquids from the inlet to the outlet
Data Source
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AI summary
An in-line tester (100) comprising: an inlet (16), connectable, in use, to an aspirator tube (18); an outlet (20) connectable, in use, to a vacuum source (22); and a chamber (14) interposed between the inlet (16) and the outlet (20), the chamber (14) comprising: a first tester (108) arranged such that fluids drawn into the chamber (14) by the vacuum source (22) come into contact therewith; a second tester (122) arranged such that fluids drawn into the chamber (14) by the vacuum source (22) pass through it; and a reservoir (114) interposed between the first tester (108) and the second tester (122); wherein the first tester (108) comprises a first colorimetric substance adapted to exhibit a colour change in the presence of a target substance, and wherein the second tester (122) comprises colorimetric capnometer, which exhibits a colour change in the presence of carbon dioxide, the in-line tester (100) further comprising a liquid-stop device (52) which, when dry, permits the passage of gas from the inlet (16) to the outlet (20), but when wetted by a liquid, inhibits or prevents the passage of fluids from the inlet (16) to the outlet (20).