Murat I, Le Bret F, Chaussain M, Saint-Maurice C
Department of Anesthesiology, Hôpital Saint-Vincent-de-Paul, Paris, France.
Acta Anaesthesiol Scand. 1988 Apr;32(3):186-92. doi: 10.1111/j.1399-6576.1988.tb02712.x.
The respiratory effects of nitrous oxide (N2O) were studied during halothane and enflurane anaesthesia in 12 children (mean age 46.4 +/- 29.3 months, mean weight 15.3 +/- 4.2 kg) during surgery under continuous extradural anaesthesia. Four equipotent anaesthetic states were studied in random order: 1) halothane 1 MAC in oxygen, 2) halothane 0.5 MAC + 50% N2O, 3) enflurane 1 MAC in oxygen, 4) enflurane 0.5 MAC +50% N2O. End-tidal fractions of CO2 (PetCO2) and halothane and enflurane were measured using infrared analysers. The respiratory variables (tidal volume VT, minute ventilation VE, respiratory frequency F, inspiratory time Ti, mean inspiratory flow VI, effective inspiratory time Ti/Ttot) were measured using a pneumotachograph. Significant changes were observed between the four states for VE, VI, F and PetCO2, whereas the values of VT, Ti and Ti/Tot did not differ significantly. The respiratory depressant effect of 1 MAC of either halothane alone or of the mixture of halothane and N2O was very similar. During enflurane anaesthesia, PetCO2 was less increased when N2O was substituted for enflurane, owing to a significant increase in respiratory frequency. A marked decrease in VE together with an increase in PetCO2 was observed during enflurane anaesthesia (states 3 and 4) when compared to the corresponding states during halothane anaesthesia (states 1 and 2). The respiratory depressant effect of enflurane is greater than that of halothane in unpremedicated children, even when substituting N2O for an equal MAC fraction of enflurane.2+ The effect of N2O on respiratory patterns seems to depend on the inhalational agent used and/or on the vesting respiratory frequency.
在12名儿童（平均年龄46.4±29.3个月，平均体重15.3±4.2千克）连续硬膜外麻醉下手术期间，研究了氧化亚氮（N2O）在氟烷和恩氟烷麻醉时对呼吸的影响。随机研究了四种等效麻醉状态：1）氟烷1个最低肺泡有效浓度（MAC）吸入氧气；2）氟烷0.5 MAC + 50% N2O；3）恩氟烷1 MAC吸入氧气；4）恩氟烷0.5 MAC + 50% N2O。使用红外分析仪测量呼气末二氧化碳（PetCO2）以及氟烷和恩氟烷的浓度。使用呼吸流速仪测量呼吸变量（潮气量VT、分钟通气量VE、呼吸频率F、吸气时间Ti、平均吸气流量VI、有效吸气时间Ti/Ttot）。在四种状态之间观察到VE、VI、F和PetCO2有显著变化，而VT、Ti和Ti/Tot的值无显著差异。单独使用1 MAC氟烷或氟烷与N2O混合物的呼吸抑制作用非常相似。在恩氟烷麻醉期间，用N2O替代恩氟烷时，由于呼吸频率显著增加，PetCO2升高较少。与氟烷麻醉期间的相应状态（状态1和2）相比，恩氟烷麻醉期间（状态3和4）观察到VE显著降低以及PetCO2升高。在未用术前药的儿童中，恩氟烷的呼吸抑制作用大于氟烷，即使将N2O替代等量MAC分数的恩氟烷也是如此。N2O对呼吸模式的影响似乎取决于所用的吸入麻醉药和/或初始呼吸频率。
