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 anesthetic technique with a standard technique of propofol for induction, and isoflurane-N2O for maintenance.

DESIGN

Prospective, randomized study.

SETTING

University-affiliated tertiary-care hospital.

PATIENTS

62 adults undergoing elective surgery using the laryngeal mask airway (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, oxygen saturation, and end-tidal carbon dioxide were recorded.

MAIN RESULTS

Time to loss of consciousness was faster after propofol (mean +/- 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 apnea after LMA insertion compared with 4 patients in the sevoflurane-N2O group (p < 0.05). Heart rate was lower 5 and 10 minutes after LMA insertion in the sevoflurane-N2O group (69 +/- 3 and 66 +/- 3 bpm) versus the control group (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 exiting the operating room (OR) between the control group (7, 8, and 10 min) and sevoflurane-N2O groups (7, 8, and 12 min, respectively). The majority of patients in both groups (92% to 97%) rated their anesthetic experience as excellent or good.

CONCLUSIONS

Sevoflurane-N2O and propofol provided comparable conditions for LMA insertion. Sevoflurane-N2O was not associated with a faster return of consciousness or faster time to exit the OR compared with isoflurane-N2O.