age, weight, height, sex; comorbidities (neurological, cardiovascular, metabolic, renal, muscular-skeletal) respiratory history positive for: previous pleuro-parenchymal diseases in the 30 days before surgery, previous chest, pleural or lung surgery, presence of pleural effusion; history of cigarettes smoking: active smoker (number of cigarettes), ex-smoker or not smoker; history of alcohol abuse (active potus, previous or abstinent); active cancer (excluding the diagnosis for surgery); SpO2, PaO2, PaO2/FiO2, PaCO2 when available; white cell number, hemoglobin and preoperative creatinine; ASA class; presence of nasogastric tube before surgery; presence of urinary catheter before surgery; blood products transfusion before surgery.