氧化亚氮对七氟醚吸入浓度的影响

Effect of supplemental nitrous oxide on inspired concentration of sevoflurane

目的了解新鲜气流中加入氧化亚氮对七氟醚吸入浓度的影响。方法20例ASAⅠ～Ⅱ级的患儿于全身麻醉下行择期骨科手术,运用自身对照方法分别先后吸入纯氧(Ⅰ组)和氧气-氧化亚氮(Ⅱ组),充分去氮,静脉诱导气管插管,控制呼吸,维持PETCO235～40mmHg。调节新鲜气体流量:Ⅰ组氧气2L/min;Ⅱ组氧气和氧化亚氮各1L/min。七氟醚蒸发器开至2%刻度,于吸入麻醉开始、麻醉后30s、1min、2min、3min直至达到目标浓度时的各个时间点测定患者七氟醚的吸入浓度及达到目标浓度的时间、MAP、HR、SPO2、PETCO2。结果(1)两组七氟醚吸入浓度逐渐升高,麻醉后6minⅠ组浓度明显高于Ⅱ组(P<0.05)。(2)吸入浓度达到目标吸入浓度的时间Ⅰ组明显短于Ⅱ组(P<0.01)。结论新鲜气流中加用氧化亚氮可减慢吸入七氟醚浓度的上升速度,应用纯氧可更快达到目标吸入浓度。

Objective To investigate the influence of nitrous oxide （N2O） inhalation on the inspired concentration of sevoflurane. Methods Twenty children scheduled for selective pacdiatric orthopaedic surgery under general anesthesia. Self-controlled trial, successively children in group I inhaled scvoflurane with O2 for anesthesia maintenance, and children in group Ⅱ inhaled sevoflurane with 50% N2O and 50% O2. Anesthesia was induced with fentanyl 2ug/kg,propofol 2.5 mg/kg and succinylcholine 1.5 mg/kg intravenously. After endotracheal intubation, all children were ventilated with PETCO2 between 35 - 40 mmHg. In group Ⅰ the fresh gas flow was 2 L/rain of O2 , and in group Ⅱ the fresh gas flow was 1 L/min of O2 with 1 L/min of N20. The sevoflurane vaporizer was kept at2%. The concentrations of sevoflurane in inspired gas were measured at 0,1,2,3 rain of scvoflurane inhalation. The MAP,HR, SPO2 and PETCO2 were also recorded at the same time points. Results The inspired concentrations of scvofluranc in group Ⅰ was higher than those in group Ⅱ （ P 〈 0. 05 ）. The time of achieving the goal concentration in group Ⅰ were shorter than those in group Ⅱ （ P 〈 0. 01 ）. Conclusion The establishment of sevoflurane concentration is slowed in the inhaled anesthesia when N2O is added in the fresh gas of oxygen because N2O can decrease the outflow concentration of scvoflurane vaporizer.