A Comparison of the Maintenance and Recovery Characteristic of Sevoflurane-Nitrous Oxide Against Isoflurane-Nitrous Oxide Anaesthesia

CL Chiu, YK Chan, GSY Ong, AE Delilkan
Correspondence: Dr C L Chiu

ABSTRACT
Background To compare the maintenance and recovery characteristics of sevoflurane and isoflurane anaesthesia in Malaysian patients.
Method This is a prospective, open labelled, randomized, controlled study. Sixty unpremedicated ASA I or II patients (aged 18-50 years), scheduled for elective breast lump excision were randomly allocated to receive either isoflurane or sevoflurane for the maintenance of anaesthesia following fentanyl and propofol intravenous induction. The systolic, diastolic, mean arterial blood pressure and heart rate were measured. The speed of recovery was measured by time to eye opening, time to following simple command, and time to correctly giving own names and address. The incidence of postoperative complication was also recorded.
Results The trend of systolic blood pressure was significantly higher in the isoflurane group as compared to the sevoflurane group for the duration of anaesthesia (p < 0.001, by ANOVA for repeated measurement) but the trend of heart rate was similar for both groups. The recovery time was faster in the isoflurane group. [mean time of eye opening (SD) = 6.8 (2.2) vs 10.7 (4.4) min, p < 0.001; mean time of sticking tongue out (SD) = 7.9 (2.9) vs 11.5 (4.7) min, p < 0.01; mean time of giving own name (SD) = 7.8 (2.7) vs 11.8 (4.8) min, p < 0.001, mean time of giving own address (SD) = 8.4 (2.9) vs 12.0 (4.7) min, p < 0.01]. No major adverse effects were encountered postoperatively and the incidences of minor adverse effects were low in both groups.
Conclusion We concluded that sevoflurane is a safe alternative to isoflurane but in these short procedures, awakening time was surprisingly slower than after isoflurane.

Keywords: Anaesthesia general; anaesthesia inhalational; isoflurane; maintenance; recovery; sevoflurane
Singapore Med J 2000; 41(11): 530-533