Comparison of the Effects of Sevoflurane and Halothane on Arterial Oxygenation during One Lung Ventilation

We investigated the effect of halothane and sevoflurane on oxygenation during one lung ventilation (OLV) in 24 patients undergoing elective thoracic procedures. After induction with thiopentone, 4-5 mg/kg and morphine 0.1 mg/kg, suxamethonium 2mg/kg was administered to facilitate tracheal intubation with a double lumen tube. Anaesthesia was maintained with 1.5-3% sevolurane (group 1, n = 12) or 1.1.5% halothane (group 2, n = 12) in 02 with N20 (1:1) and pancuronium bromide. Arterial blood gases were recorded before surgery in the lateral position with two lung ventilation (2LV), 10, 20 and 30 minutes after beginning of one lung ventilation. Morphine and endtidal inhalational anaesthetic concentration were titrated to desired anaesthetic depth and haemodynamic variables. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and central venous pressure (CVP) were measured during the study period. In both the groups there was a significant decrease of PaO2 apparent at 10 minutes after initiation of OLV. Thereafter PaO2 remained stable throughout the study period in both the groups. It is concluded that oxygenation did not differ significantly with either sevoflurane or halothane during OLV. It is also concluded that decrease in oxygenation with OLV is complete by 10 minutes of its initiation.