Beck A Ali, Boeselt T, Seppelt I M
Department ofAnaesthesia, Nepean Hospital, Penrith, New South Wales, Australia.
Anaesth Intensive Care. 2008 Sep;36(5):695-700. doi: 10.1177/0310057X0803600511.
The aim of the study was to assess Oxford Miniature Vaporizer output when mounted in-circuit during the maintenance phase of anaesthesia, using isoflurane, controlled ventilation and a fresh gas flow rate less than 1 l/min. Twenty patients of ASA Physical Status I and II were recruited from routine general surgical lists. All patients were paralysed and ventilated. An out-of-circuit isoflurane vaporiser was used during the induction period (first 20 to 30 minutes). Anaesthesia was maintained using an Oxford Miniature Vaporizer placed in-circuit, using a fresh gas flow of 500 ml/min. The end-tidal isoflurane concentration was recorded for 90 minutes at five-minute intervals using a sidestream agent analyser. Two groups were compared, with the Oxford Miniature Vaporizer dial setting at either the 0.5 mark (low output setting) or at the 1.0 mark (higher output setting). At a dial setting of 0.5, the Oxford Miniature Vaporizer produced a steady end-tidal isoflurane of 0.63% (95% confidence interval 0.60 to 0.66). However, when the dial was turned to 1.0 the output was almost always excessive and had to be reduced. These findings indicate that a stable, predictable and clinically useful output can be achieved when the Oxford Miniature Vaporizer is positioned in-circuit using low-flow and controlled ventilation.
本研究的目的是评估在麻醉维持阶段将牛津微型蒸发器安装在回路中时的输出情况，使用异氟烷、控制通气且新鲜气体流速低于1升/分钟。从常规普通外科手术患者名单中招募了20例美国麻醉医师协会（ASA）身体状况I级和II级的患者。所有患者均处于麻痹和通气状态。诱导期（最初20至3分钟）使用回路外异氟烷蒸发器。麻醉维持采用置于回路中的牛津微型蒸发器，新鲜气体流速为500毫升/分钟。使用旁流气体分析仪每隔5分钟记录90分钟的呼气末异氟烷浓度。比较了两组，牛津微型蒸发器刻度盘设置在0.5标记（低输出设置）或1.0标记（较高输出设置）。在刻度盘设置为0.5时，牛津微型蒸发器产生的呼气末异氟烷稳定在0.63%（95%置信区间0.60至0.66）。然而，当刻度盘转到1.0时，输出几乎总是过高，必须降低。这些发现表明，当牛津微型蒸发器通过低流量和控制通气置于回路中时，可以实现稳定、可预测且临床有用的输出。
