Material and methods Prospective single blinded randomized control trial, the patients were divided into two groups, LTs group and ETT group n = 60 for each group. All patients were induced anesthesia with fentanyl 1-2 mcg/kg, propofol 2 mg/kg, vecuronium 0.1 mg/kg then maintained anesthesia with air : oxygen 30%. Respirator setting are tidal volume 10 ml/kg, I/E 1:2 adjust RR base on ETCO2 keep ETCO2 35-40 mmHg.