It is known that more or less pronounced impairment of pulmonary function occurs after anesthesia. It has been demonstrated in the postoperative period in both patients undergoing general and regional anesthesia, in patients after intra-abdominal and superficial procedures, in overweight and normal-weight patients. It has also been shown that when general anesthesia is performed with the inhalation anesthetic sevoflurane, there is a slightly smaller reduction in lung function parameters than when only intravenous anesthetics are used. The purpose of this study is to evaluate lung function before induction and after awakening from general anesthesia depending on the inhalational anesthetic used in obese patients undergoing bariatric surgery