Objective To investigate the application of permissive hypercapnia in the thoraco-scopic surgery of neonates with congenital esophageal atresia.Methods Thirty newborns with con-genital esophageal atresia,seventeen males,thirteen females,aged 1-5 days,weighing 1.42-3.28 kg, ASA physical status Ⅱ or Ⅲ,undergoing the thoracoscopic surgery,were randomly divided into group P and group C,n =1 5 in each group.The newborns were intratracheally intubated and adopted intravenous anesthesia combining inhalational anesthesia.FiO 2 100%,fresh gas flow 2 L/min,then adjusted the respirator parameters according to the results of airway pressure and arterial blood gas a-nalysis.Group P maintained PaCO 2 ranging at 60-80 mm Hg,group C maintained PaCO 2 ranging at 35-45 mm Hg.Arterial blood gas analysis was conducted respectively before artificial pneumothorax (T0 ),1 5 min after foundation of artificial pneumothorax (T1 ),30 min after foundation of artificial pneumothorax (T2 ),60 min after foundation of artificial pneumothorax (T3 )and 1 5 min after artifi-cial pneumothorax (T4 ).Two hours after surgery,a chest X ray photograph was taken to observe pneumothorax.The time from the end of the surgery to the ventilator weaning was recorded. Results At T1-T3 ,the PET CO 2 [(73.93 ± 3.53 )mm Hg vs.(41.53 ± 1.59 )mm Hg,(73.46 ± 3.04)mm Hg vs.(41.30±1.29)mm Hg,(74.13±2.85)mm Hg vs.(41.67 ±1.35)mm Hg]in group P were greatly higher than those in group C (P <0.05);the arterial blood pH value of group P (7.25±0.02 vs.7.38 ± 0.03,7.24 ± 0.01 vs.7.37 ± 0.03,7.25 ± 0.01 vs.7.38 ± 0.02 )were greatly lower than those in group C (P <0.05);PaCO 2 [(74.80±2.45)mm Hg vs.(41.93±1.39) mm Hg,(75.33±2.1 9)mm Hg vs.(42.01±1.31)mm Hg,(75.20±2.08)mm Hg vs.(42.13± 1.1 9)mm Hg ] were greatly higher than those in group C (P < 0.05 ).The incidence of pneumothorax of group P was obviously lower than that of group C (6.7% vs.40.0%,P <0.05 ). There was no statistically significant difference of the time from the end of surgery to the ventilator weaning [(3.6±0.6)d vs.(3.5 ±0.6)d]between the two groups.Conclusion Permissive hyper-capnia significantly reduces the incidence of pneumothorax in the thoracoscopic surgery of neonates with congenital esophageal atresia.Permissive hypercapnia (PaCO 2 60-80 mm Hg)can be safely ap-plied to the thoracoscopic surgery of neonates with congenital esophageal atresia.