七氟醚中、低流量紧闭麻醉与双频指数监测下低流量紧闭麻醉的比较

Comparison of three anaesthetic techniques of medium-flow, low-flow and low-flow with BIS monitoring for sevoflurane anaesthesia

目的 比较七氟醚中流量、低流量及双频指数监测下低流量循环紧闭麻醉,以探讨七氟醚的应用方法。方法 96例ASA Ⅰ～Ⅱ级择期全麻手术病人,随机分为三组,A组:中流量循环紧闭麻醉,氧流量1000 ml/min;B组:低流量循环紧闭麻醉,氧流量500 ml/min;C组:双频指数监测下低流量循环紧闭麻醉,氧流量500ml/min。各组均以七氟醚环路内吸入维持麻醉。A、B两组根据临床麻醉体征和手术刺激情况调节七氟醚浓度,C组根据BIS值调节七氟醚浓度。结果 A组、B组和C组呼气末七氟醚维持浓度分别为(1.4±0.2)MAC、(1.1±0.2)MAC和(0.8±0.2)MAC水平;七氟醚总耗量分别为(13.3±1.6)m1/h、(9.6±1.5)ml/h和(7.5±1.8)ml/h,C组七氟醚总耗量最低(P<0.01);苏醒时间分别为(14.3±3.3)min、(10.5±2.8)min和(7.5±2.6)min;意识恢复时间分别为(24.5±6.1)min、(17.4±5.5)min和(12.7±4.8)min,c组苏醒时间和意识恢复时间最快;恶心呕吐发生率分别为14.5％±2.6％、10.1％±2.3％和7.5％±2.1％,c组恶心呕吐发生率最低。结论 双频指数监测下七氟醚低流量循环紧闭麻醉具有节约麻醉药,苏醒时间短和恶心呕吐发生率低的优点,是一种良好的麻醉方法。

Objective The purpose of this study was to compare the three techniques: medium-flow, low-flow and low-flow with BIS monitoring, for sevoflurane anaesthesia in terms of consumption of sevoflurane, recovery from anaesthesia, awakening time and side effects. Methods Ninety-six ASA Ⅰ - Ⅱ aged 27-51 yr undergoing elective surgery on low abdominal or low extremities under general anaesthesia were randomly divided into three groups: group A medium flow (FGF 1000 ml·min-1 ), group B low flow (FGF 500 ml·min-1 ) and group C low flow ( FGF 500 ml· min-1 ) with BIS monitoring. Sevoflurane was delivered into the circuit system from a Komesarroff vaporizer placed in-circle on the inspiration limb. In groups A and B the concentration of sevoflurane delivered was adjusted according to clinical signs of anesthesia, while in group C according to the BIS value (at 46 ±10). Before induction of anesthesia the patient was denitrogenated for 3 min with high flow rate of oxygen (6 L ·min-1 ). Anesthesia was induced with midazolam 0.03 mg·kg-1 , fentanyl 1 μg·kg-1 , propofol 2 mg·kg-1 and vecuronium 0.1 mg·kg-1. After intubation, the patient was mechanically ventilated and PaCO2 was maintained at 35 - 45 mm Hg. Anesthesia was maintained with sevoflurane. The consumption of sevoflurane was calculated from deduction of the volume of sevoflurane left in the vaporizer from 30ml of sevoflurane added initially into the vaporizer. The duration from termination of sevoflurane administration to eye-opening and orientation and the incidence of nausea and vomiting were recorded. Results During surgery the end-tidal sevoflurane concentrations were maintained at (1.40±0.20) MAC (in group A), (1.10± 0.20) MAC (in group B) and (0.80±0.20) MAC (in group C) respectively. The volume of sevoflurane consumed was (13.3 ± 1.6) ml·h-1 (group A), (9.6 ±1.5 ) ml · h ( group B) and (7.5±1.8)ml·h-1( group C) respectively. The time to regain consciousness were (14.3±3.3) min (group A), (10.5 ± 2.8) min (group B) and (7.5±2.6) min (group C). The times to full orientation were (24.5±6.1) min (group A), (17.4±5.5) min (group B) and (12.7 ± 4.8) min (group C). The incidence of nausea and vomiting was 14.5 % ± 2.6 % (group A), 10.1 % ±2.3 % (group B) and 7.5 % ±2.1 % (group C) . Conclusion Low-flow closed circuit anaesthesia combined with BIS monitoring has the advantages of least sevoflurane consumed, fastest recovery and least incidence of nausea and vomiting and is the best technique for sevoflurane anaesthesia.