Sidestream Gas Analyser Sequencing for Accurate Gas Exchange Measurement
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Solution Overview
Problem
Differences in gas analyser characteristics and calibration between pre- and post-gas exchange measurements introduce errors in determining gas exchange, particularly in ECMO and mechanical ventilation systems.
Innovation Solution
A system using a single gas analyser connected to both inlet and outlet lines to sequentially measure gas samples, with a processor determining gas fractions and exchange rates, and optionally including a gas sample conditioner to account for water vapour removal, ensuring accurate gas exchange measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate gas analysers are used for pre- and post-gas exchange measurements, then measurement coverage is improved, but measurement precision deteriorates due to inter-analyser differences and calibration variations
Solution Approach 1:
The patent merges the function of multiple gas analysers into a single gas analyser that sequentially measures both pre- and post-gas exchange gas samples. This eliminates inter-analyser differences and calibration variations while maintaining the ability to measure gas concentrations at different points in the gas exchange system.
Solution Approach 2:
The single gas analyser is designed to perform multiple functions by sequentially analyzing different gas samples from both the pre- and post-gas exchange streams. This multi-functional approach allows one analyser to replace what would traditionally require multiple specialised analysers.
2Measurement precision
If a single gas analyser is used for sequential measurement, then measurement precision is improved by eliminating inter-analyser differences, but measurement time increases due to sequential analysis requirement
Solution Approach 1:
The gas analyser operates in a periodic sequential manner, switching between measuring pre- and post-gas exchange samples at regular intervals. This periodic action allows the single analyser to maintain measurement precision while systematically collecting data from both streams over time.
Solution Approach 2:
The system maintains continuous measurement capability by sequentially switching between pre- and post-gas exchange samples without interruption. The useful action of gas concentration measurement continues uninterrupted, ensuring that gas exchange data is continuously available while using a single analyser.
3Measurement precision
If gas sample conditioning is applied to remove water vapour, then measurement precision is improved, but measurement accuracy may deteriorate due to potential gas composition changes
Solution Approach 1:
A gas sample conditioner acts as an intermediary component between the gas stream and the analyser. It selectively removes water vapour while attempting to preserve the overall gas composition, serving as a mediator that improves measurement precision without significantly compromising the representativeness of the gas sample.
Solution Approach 2:
The gas sample conditioner modifies specific parameters of the gas sample (removing water vapour) while maintaining other critical parameters (gas composition for analysis). This selective parameter change improves measurement precision by eliminating water vapour interference while preserving the integrity of the gas exchange data.
Data Source
AI summary
A system (100; 1) for analysing gas concentrations before and after a point of gas exchange (PGE; 3, 23) is disclosed. The system (100; 1) comprises a gas inlet line (101; 11, 33a) for conveying a flow of an input gas mixture towards the point of gas exchange (PGE; 3, 23), a gas outlet line (103; 13, 33b) for conveying a flow of an output gas mixture away from the point of gas exchange (PGE; 3, 23), and a gas analyser (105) that is connected to both the gas inlet line (101; 11, 33a) and the gas outline line (103; 13, 33b) and configured to sequentially receive and analyse gas samples from the gas inlet line (101; 11, 33a) and the gas outlet line (103; 13, 33b) in order to determine a presence of a specific gas in the input gas mixture and the output gas mixture.