Background: Tracheal intubation during sevoflurane induction is frequently facilitated with i.v. propofol. We designed a dose-response study to evaluate the intubating conditions, and the incidence and duration of apnea after i.v. propofol in children.
Methods/materials: Sixty healthy children were randomly assigned to 0, 0.5, 1, 2 or 3 mg x kg(-1) i.v. propofol during sevoflurane/nitrous oxide anesthesia. Tracheal intubation was performed approximately 30 s after propofol by an anesthesiologist who was blind to the treatment. The anesthesiologist assessed the responses to laryngoscopy and intubation using a standardized scale. Incidence and duration of apnea after propofol as well as heart rate, and systolic blood pressure before and after laryngoscopy were recorded. Data were analyzed using one-way and repeated measures ANOVA, the Jonckheere-Terpstra test, and logistic regression, with P < 0.05 accepted.
Results: The laryngoscopy score after 3 mg x kg(-1) propofol was less than that after 0 mg x kg(-1) (P < 0.01) and 0.5 mg x kg(-1) (P < 0.05). Incidence of apnea after propofol 3 mg x kg(-1), 8/10, was greater than after 0 mg x kg(-1), 3/14 (P < 0.011) and 0.5 mg x kg(-1), 3/12 (P < 0.03). Duration of apnea after 3 mg x kg(-1) was greater than after 0 and 0.5 mg x kg(-1) (P < 0.01). The risk of apnea increased 1.83 fold for each 1 mg x kg(-1) dose increase in propofol (P < 0.01). Mean heart rate and systolic pressure decreased with the main effect, time.
Conclusion: During sevoflurane/nitrous oxide anesthesia, propofol 3 mg x kg(-1) provides superior intubating conditions with an increased incidence of and prolonged apnea compared with 0 and 0.5 mg x kg(-1).