Department of Anaesthesiology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany.
Br J Anaesth. 2013 Jun;110(6):957-65. doi: 10.1093/bja/aet018. Epub 2013 Mar 5.
It is unclear what factors affect the uptake of sevoflurane administered through the membrane oxygenator during cardiopulmonary bypass (CPB) and whether this can be monitored via the oxygenator exhaust gas.
Stable delivery of sevoflurane was administered to 30 elective cardiac surgery patients at 1.8 vol% (inspiratory) via the anaesthetic circuit and ventilator. During CPB, sevoflurane was administered in the oxygenator fresh gas supply (Compactflo Evolution™; Sorin Group, Milano, Italy). Sevoflurane plasma concentration (SPC) was measured using gas chromatography. Changes were correlated with bispectral index (BIS), patient temperature, haematocrit, plasma albumin concentration, oxygenator fresh gas flow, and the sevoflurane concentration in the oxygenator exhaust at predefined time points.
The mean SPC pre-bypass was 54.9 µg ml(-1) [95% confidence interval (CI): 50.6-59.1]. SPC decreased to 43.2 µg ml(-1) (95% CI: 40.3-46.1; P<0.001) after initiation of CPB, and was lower still during rewarming and weaning from bypass, 39.4 µg ml(-1) (95% CI: 36.6-42.3; P<0.001). BIS did not exceed a value of 55. SPCs were higher during hypothermia (P<0.001) and with an increase in oxygenator fresh gas flow (P=0.015), and lower with haemodilution (P=0.027). No correlation was found between SPC and the concentration of sevoflurane in the oxygenator exhaust gas (r=-0.04; 95% CI: -0.18 to 0.09; P=0.53).
The uptake of sevoflurane delivered via the membrane oxygenator during CPB seems to be affected by hypothermia, haemodilution, and changes in the oxygenator fresh gas supply flow. Measuring the concentration of sevoflurane in the exhaust from the oxygenator is not useful for monitoring sevoflurane administration during bypass.
目前尚不清楚哪些因素会影响体外循环（CPB）期间通过膜式氧合器给予的七氟醚摄取，以及是否可以通过氧合器废气进行监测。
30 名择期心脏手术患者通过麻醉回路和呼吸机以 1.8 体积%（吸入）稳定给予七氟醚。在 CPB 期间，将七氟醚通过膜式氧合器新鲜气体供应（Sorin Group，Milano，意大利的 Compactflo Evolution™）给予。使用气相色谱法测量七氟醚血浆浓度（SPC）。在预定义的时间点，将变化与双谱指数（BIS）、患者体温、血细胞比容、血浆白蛋白浓度、氧合器新鲜气体流量以及氧合器废气中的七氟醚浓度相关联。
旁路前平均 SPC 为 54.9 µg ml(-1) [95%置信区间（CI）：50.6-59.1]。CPB 启动后，SPC 降至 43.2 µg ml(-1)（95% CI：40.3-46.1；P<0.001），在复温期间和从旁路脱机期间仍较低，为 39.4 µg ml(-1)（95% CI：36.6-42.3；P<0.001）。BIS 未超过 55。低温时 SPC 较高（P<0.001），氧合器新鲜气体流量增加时 SPC 较高（P=0.015），血液稀释时 SPC 较低（P=0.027）。SPC 与氧合器废气中七氟醚浓度之间未发现相关性（r=-0.04；95% CI：-0.18 至 0.09；P=0.53）。
CPB 期间通过膜式氧合器给予的七氟醚摄取似乎受到低温、血液稀释和氧合器新鲜气体供应流量变化的影响。测量氧合器废气中七氟醚的浓度对于监测旁路期间七氟醚的给予并不有用。
