Anaesthetic induction time for tracheal intubation using sevoflurane or halothane in children

The current study was designed to determine the anaesthetic induction time required for tracheal intubation (Time(EI)) with equipotent inspired concentrations of 5% sevoflurane and 2.5% halothane in oxygen. Time(EI) that prevents 50% and 95% of patients from coughing and gross purposeful muscular movements after intubation was defined as Time(EI)50 and Time(EI)95, respectively. Thirty-six patients aged 1-7 years were enrolled in the study. Anaesthesia was induced via mask and when Time(EI) attained a predetermined value, intubation was performed using an uncuffed tube. Each Time(EI) at which tracheal intubation was attempted was predetermined according to the up-and-down method. When intubation was accomplished without gross purposeful muscular movements, it was considered a smooth intubation. Determination with this method revealed that Time(EI)50 and Time(EI)95 for the sevoflurane/halothane groups were 147/214s and 194/255s, respectively. In conclusion, it is possible to determine Time(EI) using an inspired sevoflurane concentration of 5% and halothane 2.5% in oxygen. The technique with 5% sevoflurane seems more practical for paediatric anaesthesia induction in busy clinical situations.