For maintenance of general anesthesia an inhalation anesthetic isoflurane will be used in inspired concentrations of 1.5 to 3.0 % and analgesia will be assured by a continuous infusion of 0.3 - 0.5 µg/kg/min of remifentanyl. Vecuronium bromide will be administered if muscle relaxation of higher degree was needed of any reason. Low-flow anesthetic technique will be performed by further continuously inhaled fresh gas flow up to 1.5 L/min of oxygen and air mixture to reach 40% of FiO2. Patients will be mechanically ventilated with predetermined tidal volume (VT) (5 - 7 ml/kg of BW), positive end-expiratory pressure (PEEP) between 3 - 5 cm H2O and respiratory rate (RR) between 12 and 15 per minute to maintain ETCO2 between 30 and 35 mm Hg.