Since the precise measurement of halothane-concentration in the patients gas support during routine anesthesia still requires much effort, the accuracy of the vaporizers halothane output remains important for the safety of anesthesia and the education of younger anesthesiologists. In the present study 30 halothane vaporizers (14 Fluotec Mark 3/Cyprane Ltd., 12 Vapor 19/Dr?ger, 4 Abingdon/Penlon) were removed from the operating rooms in the University Hospital G?ttingen to test their accuracy. The measurements were performed with a masspectrometer under standardized laboratory conditions with varied temperatures (10 degrees, 21 degrees, 35 degrees C), gasflows (3, 5, 8 l/min) and compositions of carrier gas (100% O2, N2O/O2 = 2/1). All vaporizers in this study showed a light tendency to higher halothane outputs for low concentration adjustments and to distinct lower outputs for higher concentration adjustments. The Vapor 19 vaporizers compensated well with changes of temperatures and gasflows but had a distinct dependency on carriers gas compositions. The Fluotec Mark 3 vaporizers output depended on the temperature and gasflow but was almost unaffected by the carrier gas composition. Tremendous deviations appeared with the Abingdon vaporizers, which seamed to be without any temperature compensation and which were highly gas flow dependent. It can be concluded from our results that vaporizers according to their construction tend to be imprecise.
Anesthesia Anesthesiology