Sevoflurane concentration for cannulation in developmental disabilities

The goal of this study was to compare the end-tidal sevoflurane concentration and time for intravenous cannulation at induction of anesthesia using sevoflurane with or without nitrous oxide in healthy children and in those with developmental disabilities.

Normal and developmentally disabled children were anesthetized by inhalation of sevoflurane with nitrous oxide or with nitrous oxide-free oxygen, and intravenous cannulae were introduced. Nitrous oxide was stopped after loss of consciousness. The following parameters were recorded for each patient: age, gender, height, weight, BMI, duration of intravenous cannulation, end-tidal concentration of sevoflurane at the completion of intravenous cannulation, and use of nitrous oxide. For each parameter except gender, p-value were calculated by one-way analysis of variance (ANOVA). For gender, p-value were calculated using the Fisher method. Two-way ANOVA was performed to evaluate the effect of patient health status and nitrous oxide use on the end-tidal concentrations of sevoflurane and the time required for intravenous cannulation.

The end-tidal sevoflurane concentrations at the completion of the intravenous cannulation had received a significant main effect of the factor "the use of nitrous oxide" (F(1,166) = 25.8, p < 0.001, η² = 0.13) and a small effect of the factor "the patient health status" (F(1,166) = 0.259, p = 0.611, η² = 0.001). However, the time required for intravenous cannulation was not significantly affected by either of the two factors, "the use of nitrous oxide" (F(1,166) = 0.454, p = 0.501, η² = 0.003) and "the patient health status" (F(1,166) = 0.308, p = 0.579, η² = 0.002).

Between the healthy children and the children with developmental disabilities, no significant differences in the time required for the intravenous cannulation from the beginning of anesthetic induction. However, the end-tidal sevoflurane concentrations at the completion of the intravenous cannulation was significantly different. Sevoflurane in alveoli might be diluted by nitrous oxide.