Sevoflurane-N2O versus propofol/isoflurane-N2O during elective surgery using the laryngeal mask airway in adults

Study Objectives: To compare a sevoflurane-nitrous oxide (N2O) general anes thetic technique with a standard technique of propofol for induction, and i soflurane-N2O for maintenance. Design: Prospective randomized Study. Setting: University-affiliated tertiary-care hospital. Patients: 62 adults undergoing elective surgery using the laryngeal mask ai rway (LMA). Interventions: Patients received either the standard technique of propofol for induction and isoflurane-N2O for maintenance (controls) or sevoflurane- N2O for both induction and maintenance of general anesthesia. Measurements: Induction and emergence times, heart rate blood pressure, oxy gen saturation, and end-tidal carbon dioxide were recorded. Main Results: Time to loss of conscious ness was faster after propofol (mea n +/- SEM:51 +/- 3 sec) than after sevoflurane-N2O (85 +/- 10 sec; p < 0.05 ). Ready for surgery times, were however, similar between groups (10 +/- 1 vs. 11 +/- 1 min, respectively). All patients in the control group had apne a after LMA insertion compared with 4 patients in the sevoflurane-H2O group (p < 0.05). Heart rate was lower 5 and 10 minutes after LMA insertion in t he sevoflurane-N2O group (69 +/- 3 and 66 +/- 3 bpm) versus the control gro up (81 +/- 3 bpm and 74 +/- 3 bpm p < 0.05). After cessation of anesthetic gases, there were no differences in time to LMA removal, eye opening or exi ting the operating room (OR) between the control group (7, 8 and 10 min) an d sevoflurane-N2O groups (7, 8 and 12 min, respectively). The majority of p atients in both groups (92% to 97%) rated their anesthetic experience as ex cellent or good. Conclusions: Sevoflurane-N2O and propofol provided comparable conditions fo r LMA insertion. Sevoflurane-N2O was not associated with a faster return of consciousness or faster time to exit the OR compared with isoflurane-N2O. (C) 2000 by Elsevier Science Inc.