[Sevoflurane or halothane in inhalational anesthesia induction in childhood. Anesthesia quality and fluoride level]

Due to its low blood:gas partition coefficient (0.69) and its neutral odor, sevoflurane (S) is suitable for inhalational induction of anaesthesia. At the moment halothane (H) is preferentially used for this purpose due to its non-irritating odor and the smoothness of anaesthetic action. However, experience is limited with the use of S in children, and concern exists about potential renal toxicity of its metabolite, i.e. fluoride. Therefore, we compared S and H in an open, randomized phase III trial.

With approval of the ethics committee and written informed parental consent, 40 children (age 1-10, mean 5.3 years, ASA class I and II) had anaesthesia induced without premedication (fresh gas flow 6 l/min, N2O/O2 = 65/35). Concentration of volatile anaesthetics was increased every 3-5 breaths (S: 0.8...3.2 vol%, H: 0.4...1.6 Vol%). The ciliary reflex was tested until it disappeared. Airway reflexes and excitation were quantified using a score. Upon venipuncture, relaxation and intubation, anaesthesia was maintained with S (Fi: 2.4 vol%) or H (Fi: 1.2 vol%) in N2O/O2 (3 l/min, etCO2 35-38 mm HG). Alfentanil was supplemented in repeated doses of 20 micrograms/kg. ECG, NIBP, SpO2, Fi and Fet of CO2 and volatile anaesthetics were continuously recorded. At the end of surgery anaesthetics were terminated abruptly and fresh gas flow was increased to 6 l/min O2. Time to the first purposeful movement was registered. Serum fluoride levels were determined immediately after venipuncture, at the end of surgery and 70 min later. Time to possible discharge from the PACU was quantified using a modified Aldrete score. Data were analysed with descriptive methods, Student's t-test or non-parametric tests as appropriate.

Groups did not differ with respect to age, weight, sex, or type of surgery. Total dose of anaesthetics was 1.60 MACxh for S and 1.77 MACxh for H (p = 0.68). Table 6 shows the essential data. Mean arterial blood pressures and heart rate remained within +/- 20% of age-related normal values (Table 7). Mean serum fluoride level was 23.1 +/- 1.2 mumol/l at the end of surgery and decreased to 18.6 +/- 0.970 min later (Fig. 3).

Sevoflurane is an alternative to halothane in pediatric inhalational anaesthesia, with a comparable, low incidence of airway irritation and smoothness of induction. Because of the significantly faster induction and recovery it seems superior to halothane. With the fluoride levels measured, an impairment of renal function is unlikely.