Prasser C, Zelenka M, Gruber M, Philipp A, Keyser A, Wiesenack C
Department of Anaesthesiology, University Hospital of Regensburg, Franz-Josef-Strauss-Allee, Regensburg, Germany.
Eur J Anaesthesiol. 2008 Feb;25(2):152-7. doi: 10.1017/S0265021507001330. Epub 2007 Jul 27.
It has been demonstrated that volatile anaesthetics have cardioprotective properties during open-heart procedures, especially when administered continuously. European Council Directive 93/42/EEC concerning medical devices bans the supplementary incorporation of anaesthetic vaporizers in the bypass circuit. Since the uptake of volatile anaesthetics via diffusion membrane oxygenators is severely reduced, it is hypothesized that clinically relevant concentrations of sevoflurane will remain in the patients' blood following saturation with a volatile agent before start of cardiopulmonary bypass. This study was designed to compare conventional and diffusion membrane oxygenators regarding their in vivo elimination of sevoflurane.
Twenty patients undergoing elective coronary bypass surgery were randomly allocated to two groups, either using a conventional polypropylene membrane oxygenator or a plasma-tight poly-(4-methyl-1-pentene) membrane oxygenator in a miniaturized extracorporeal circuit. Anaesthesia was maintained with sevoflurane, which was stopped at the start of cardiopulmonary bypass. During cardiopulmonary bypass, sevoflurane concentration was measured in blood and in the exhausted gas from the oxygenator.
The elimination of sevoflurane, expressed as the relative blood concentration, was significantly increased in polypropylene membrane oxygenators compared to poly-(4-methyl-1-pentene) membrane oxygenators. This resulted in an approximately threefold higher sevoflurane blood concentration in the poly-(4-methyl-1-pentene) group over the course of cardiopulmonary bypass.
With the incorporation of a poly-(4-methyl-1-pentene) oxygenator in a miniaturized bypass circuit, relevant concentrations of a previously applied volatile agent can be maintained even without further supply throughout cardiopulmonary bypass. This might be an alternative approach to cardioprotection when sevoflurane cannot be administered through cardiopulmonary bypass.
业已证明，挥发性麻醉剂在心脏直视手术过程中具有心脏保护特性，尤其是持续给药时。欧洲理事会关于医疗器械的93/42/EEC指令禁止在体外循环回路中额外添加麻醉蒸发器。由于通过扩散膜氧合器摄取挥发性麻醉剂的量会大幅减少，因此推测在开始心肺转流前用挥发性麻醉剂使患者饱和后，患者血液中仍会保留临床相关浓度的七氟醚。本研究旨在比较传统膜氧合器和扩散膜氧合器对七氟醚的体内清除情况。
20例行择期冠状动脉搭桥手术的患者被随机分为两组，分别在小型体外循环回路中使用传统聚丙烯膜氧合器或血浆致密型聚（4-甲基-1-戊烯）膜氧合器。用七氟醚维持麻醉，在心肺转流开始时停止给药。在心肺转流期间，测量血液和氧合器废气中的七氟醚浓度。
以相对血药浓度表示，聚丙烯膜氧合器对七氟醚的清除率相比聚（4-甲基-1-戊烯）膜氧合器显著增加。这导致在心肺转流过程中，聚（4-甲基-1-戊烯）组的七氟醚血药浓度高出约三倍。
在小型体外循环回路中使用聚（4-甲基-1-戊烯）氧合器，即使在整个心肺转流过程中不再额外供应，也能维持先前应用的挥发性麻醉剂的相关浓度。当无法通过心肺转流给予七氟醚时，这可能是一种心脏保护的替代方法。
