Comparison of an infrared anaesthetic agent analyser (Datex-Ohmeda) with refractometry for measurement of isoflurane, sevoflurane and desflurane concentrations
To assess agreement between infrared (IR) analysers and a refractometer for measurements of isoflurane, sevoflurane and desflurane concentrations and to demonstrate the effect of customized calibration of IR analysers. In vitro experiment. Six IR anaesthetic monitors (Datex-Ohmeda) and a single port...
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Published in | Veterinary anaesthesia and analgesia Vol. 41; no. 4; pp. 386 - 392 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Ltd
01.07.2014
Blackwell Pub Blackwell Publishing Ltd |
Subjects | |
Online Access | Get full text |
ISSN | 1467-2987 1467-2995 1467-2995 |
DOI | 10.1111/vaa.12118 |
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Summary: | To assess agreement between infrared (IR) analysers and a refractometer for measurements of isoflurane, sevoflurane and desflurane concentrations and to demonstrate the effect of customized calibration of IR analysers.
In vitro experiment.
Six IR anaesthetic monitors (Datex-Ohmeda) and a single portable refractometer (Riken).
Both devices were calibrated following the manufacturer’s recommendations. Gas samples were collected at common gas outlets of anaesthesia machines. A range of agent concentrations was produced by stepwise changes in dial settings: isoflurane (0–5% in 0.5% increments), sevoflurane (0–8% in 1% increments), or desflurane (0–18% in 2% increments). Oxygen flow was 2 L minute−1. The orders of testing IR analysers, agents and dial settings were randomized. Duplicate measurements were performed at each setting. The entire procedure was repeated 24 hours later. Bland–Altman analysis was performed. Measurements on day-1 were used to yield calibration equations (IR measurements as dependent and refractometry measurements as independent variables), which were used to modify the IR measurements on day-2.
Bias ± limits of agreement for isoflurane, sevoflurane and desflurane were 0.2 ± 0.3, 0.1 ± 0.4 and 0.7 ± 0.9 volume%, respectively. There were significant linear relationships between differences and means for all agents. The IR analysers became less accurate at higher gas concentrations. After customized calibration, the bias became almost zero and the limits of agreement became narrower.
If similar IR analysers are used in research studies, they need to be calibrated against a reference method using the agent in question at multiple calibration points overlapping the range of interest. |
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Bibliography: | http://dx.doi.org/10.1111/vaa.12118 istex:6E2393B56675EBB4EC06F8BC9BC0F97A5001492C ark:/67375/WNG-BFS0L7H3-T ArticleID:VAA12118 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 1467-2987 1467-2995 1467-2995 |
DOI: | 10.1111/vaa.12118 |