半紧闭麻醉时氧流量对异氟醚吸入和呼出浓度的影响

目的 研究半紧闭麻醉时不同氧流量对异氟醚吸入和呼出浓度的影响。方法 60例静吸复合麻醉腹部手术病人随机分为氧流量2L/min和3L/min两组,挥发器开启浓度均为2％,辅助用丙泊酚和芬太尼维持适当麻醉深度。用Datex AS/3监测仪监测异氟醚吸入浓度(FI)和呼气末浓度(FA)。结果 开始吸入异氟醚的2～5 min内,FI和FA均上升迅速,以后上升速度减慢,3L/min组FI和FA均高于2L/min组。两组FA/FD随时间变化趋势一致,但氧流量3L/min组明显高于2L/min组,而FA/FI两组无明显差异。氧流量2L/min和3L/min组达到FA)_(MAC)时间分别为6.5和6.2min,达到FI_(max)时间3L/min组显著短于2L/min组(P<0.01),而达到FA_(max)时间两组间无显著性差异。结论 半紧闭麻醉时,氧流量增加使异氟醚FI、FA及FA/FD增加,而对机体摄取异氟醚的速率无影响。

Effects of oxygen flow on inspired and expired isoflurane concentration during partly closed circuit anesthesia

Objective To evaluate the effects of oxygen flow on inspired and expired isoflurane concentration during partly closed circuit anesthesia. Methods Sixty patients undergoing abdominal surgery were randomly divided into 2 L/min and 3 L/min of oxygen flow groups. All patients received intravenous combined inhalation anesthesia with delivered concentration(FD)of 2% isoflurane in fresh oxygen inflow of 2 L/min or 3 L/min and administrated propfol and fentanyl. Inspired and expired isoflurane concentration(FI,FA) were continuously monitored with Datex AS/3 monitor. Results FI and FA were rapidly increased in 3-5 min after beginning inhalation of isoflurane, then increased by inches. FI and FA in 3 L/min oxygen flow group were much higher than those in 2 L/min oxygen flow group. The trend of FA/FD were the same in both groups. FA/FD in 3 L/min oxygen flow group were much higher than those in 2 L/min oxygen flow group, and FA/FI had no significant differences in both groups. The time of FA reaching to 1 MAC were 6. 5 min and 6. 2 min in 2 L/min and 3 L/min of oxygen groups,respectively. The time of FI reaching to maximal concentration in 3 L/min of oxygen flow group was much shorter than that in 2 L/min of oxygen group, but the time of FA reaching to maximal concentration in both groups were no significant differences. Conclusion During party closed circuit anesthesia,FI,FA,and FA/FD increase with the increase of oxygen flow,and oxygen flow has no effects on rate of isoflurane uptake.