Effect of Preoperative Budesonide Inhalation on Arterial Blood Oxygenation and Intrapulmonary Shunt During OLV

Inclusion Criteria: * Aged 45 yr to 65 yr ,height 155-176cm,weight 45-75kg,body mass index(BMI)18-27kg/m2,ASA Physical Status Classifications I to II,left-lateral position during OLV ,normal cardiac and pulmonary function ,and no cardiac,hepatic,renal and endocrine diseases.Diagnosed with uncomplicated lung cancer and was to receive video-assist thoracoscopic lobectomy under general anesthesia. Exclusion Criteria: * FEV1/FVC\<70%,asthma,chronic obstructive pulmonary disease,acute lung infection,past history of thoracic surgery. preoperative glucocorticoid medication,preoperative chemotherapy,SpO2 kept below 90% for more than 15 minutes during operation,blood transfusion during operation,OLV less than an hour,occurrence of severe complications like allergic shock.