Estudo nåo-comparativo sobre o sevoflurano na anestesia de pacientes adultos ambulatóriais / A non-comparative study on sevoflurane in adult outapatients

RESUMO

Background and objectives - Sevoflurane is a new inhalational anesthetic with short induction and recovery times, which make it appropriate for outpatient surgery. The purpose of this study is to present our experience with sevoflurane in adult outpatients. Methods - Sevoflurane was used for maintenance of anesthesia in 40 adult patients, with age range of 30.9 +- 10.5 years and ASA physical status I or II, undergoing ambulatory procedures. Induction of anesthesia was obtained with midazolam 0.25 mg/Kg-1 and alfetanil 30 ug/Kg-1 and the patients were maintained with N2O/O2 (60/40 per cent), under tracheal intubation and controlled mechanical vntilation, in a rebreating system with CO2 absorption. Sevoflurane was administered via the Ohmeda Sevotec 5 vaporizer. Monitoring included SpO2, PETCO2, ETN2O, and ETSEVO, with the aid of the CapnomacOhmeda Datex. Systol;ic and diastolic blood pressure and heart rate were registered at the following moments: 1) one minute before induction; 2) one minute after tracheal intubation; 3) one minute before surgical incision; 4) five minutes after surgical incision; 5) ten minutes after discontinuation of sevoflurane. The following parameters related to recovery from anesthesia were studied: awakening time, time to verbal command, time to orientation, time to liberation from phase I, time to liberation from phase II (hospital discharge). Time of exposure to sevoflurane and untoward effects were also registered. Results - Mean time of exposure to sevoflurane was 81.1 +- 43.9 min and mean values of end tidal sevoflurane were 1.07 +- 0.40 per cent one miute after tracheal intubation, 1.75 +- 0.38 per cent one minute before surgical incision and 1.85 +- 0.61 per cent five minutes after surgical incision. Recovery times from anesthesia were as follows: awakening 19.1 +- 9.5 min; response to command 21.8 +- 11.2 min; orientation 26.8 +- 11.5 min; phase I 53.2 +- 9.7 min; phase II 144.9 +- 41.7 min. Hypotension (decrease in SBP greater than 30 per cent of pre induction values) ocurred in 17 patients (42.5 per cent) and was promptly controlled by reducing the inspired concentration of sevoflurane. Awareness did not occur and acceptance was good in all cases. Conclusions - The fast recovery and the low incidence of untoward effects indicate that sevoflurane is an appropriate anesthetic for outpatients