目的　观察异丙酚和安氟醚对单肺通气 (OLV )肺内分流的影响 ,及其肺动、静脉血浆一氧化氮 (NO )和内皮素 (ET )的变化。方法　择期开胸OLV病人 30例 ,随机均分为两组 ,安氟醚组吸入浓度 1 8% ,而异丙酚组微泵输入剂量 6mg·kg-1·h-1。监测双肺通气 (TLV )30min、OLV 30、6 0min时的桡、肺动脉血气及肺动、静脉血浆NO和ET浓度。结果　OLV后 ,两组病人不同时点肺内分流值 (Qs /Qt)均比TLV时显著增加 (P <0 0 1) ,其中安氟醚组较异丙酚组增加更为明显 (P <0 0 5 )。两组肺动、静脉血NO浓度在TLV、OLV期间变化不显著 (P >0 0 5 )。异丙酚组OLV后肺静脉血ET浓度比TLV时上升 (P <0 0 1) ,而安氟醚组其变化不明显 (P >0 0 5 )。结论　临床剂量异丙酚对缺氧性肺血管收缩无明显抑制作用。OLV肺泡缺氧可引起肺内皮细胞分泌ET或肺组织对ET清除作用减弱 ,安氟醚对其有抑制作用。 Objective To observe the effects of propofol and enflurane on pulmonary shunt in single pulmonary ventilation (OLV) and the changes of pulmonary artery and venous blood plasma nitric oxide (NO) and endothelin (ET). Methods Thirty patients with OLV undergoing elective thoracotomy were randomly divided into two groups. The inhalation concentration was 18% in the enflurane group, and 6 mg · kg-1 · h-1 in the propofol group. Radial and pulmonary arterial blood gases and pulmonary arterial and venous plasma concentrations of NO and ET were measured at both lung ventilation (TLV) 30min and OLV 30 and 60min. Results After OLV, the values ​​of Qs / Qt at different time points in both groups were significantly higher than those at TLV (P <0.01), of which the enflurane group increased more significantly than the propofol group (P < 0 0 5). Pulmonary artery and venous blood NO levels did not change significantly between TLV and OLV in two groups (P> 0.05). Compared with TLV, the concentration of ET in OLV after propofol group increased (P <0.01), while that in enflurane group was insignificant (P> 0.05). Conclusion The clinical dose of propofol has no obvious inhibitory effect on hypoxic pulmonary vasoconstriction. OLV alveolar hypoxia can cause pulmonary endothelial cells to secrete ET or lung tissue weakened the clearance of ET, and enflurane inhibition.