The end expiratory nitrous oxide and Isoflurane cencentration, FiO 2, SpO 2, EtCO 2, HR and MAP were monitored continuously during the whole procedure Results: The safety of the two groups was much the same.

• 整个麻醉过程中连续监测呼末N2 O浓度 ,呼末异氟醚的浓度 ,FiO2 、SpO2 、EtCO2 、HR和MAP。