성인 환자의 전신 마취동안 사용되는 O2 와 N2O 의 적정유량

Background: During adult general anesthesia, we used 3~5 L/min of fresh gas flow(FGF) but low FGF are employed, the amount of anesthetic consumption and air contamination can be reduced. The aim of this study was to determine the minimal appropriate inflow rate of oxygen and nitrous oxide during semiclosed circle technique. Methods: We selected 40 patients, ASA group l or 2, scheduled for elective, nonabdominal surgery under general anesthesia with semiclosed circle system. Anesthesia was maintained with 50% oxygen, nitrous oxide and enflurane, controlled ventilation was used; rate of 10/min, tidal volume of 10 ml/kg. After induction and vital signs stabilized, FGF was changed to 4 L, 3 L, 2 L and 1L/min at interva1 of 30 minutes. We observed mean airway pressure and arterial blood gas tensions. Results: The changes of mean airway pressure did not correlated with fresh gas inflow rate. In arterial blood gas analysis, PaO showed a decreasing tendency significantly according to decreasing fresh gas inflow rate(p