The ED₅₀ Of Propofol For Successful Intubation Without Neuromuscular Blockade In Children Under 3 Years Of Age

OBJECTIVES The purpose of this study was to investigate the ED₅₀ of propofol as an induction agent for endotracheal intubation without muscle relaxants in the children younger than 3 years of age.METHODS We conducted a prospective, controlled trial in children younger than 3 years of age who underwent elective cardiac surgery (including VSD, ASD and PDA). ASA physical status wasâ… orâ…¡, Thirty-one patients were induced and intubated with only propofol for the induction of anesthesia (group P). Twenty-two patients were induced and intubated with 5% sevoflurane and propofol together (group SP). The ED₅₀ of propofol for successful endotracheal intubation was determined by using Dixon's up-and-down method. The effective dose (ED50) of propofol enabling successful tracheal intubation was determined by calculating the midpoint concentration of all independent pairs of patients after at least seven crossover points (i.e. success to failure of tracheal intubation) were obtained. The ED50 was defined as the average of crossover midpoints in each pair. The maximal likelihood estimators of the model variables were performed also using a probit analysis that furnished the best-fitting sigmoid curve. Haemodynamic data changes(including MAP, HR) of baseline, preintubation, and after intubation were recorded and compared by repeated measures ANAOVA., and P-value <0. 05 was significantRESULTS The bolus ED₅₀ of propofol alone (group P) required for successful tracheal intubation was 4.84 (0.28) mg/kg, and 2.67 (0. 18) mg/kg in group SP. From probit analysis, ED₉₅ of propofol was 5. 84mg/kg (95% confidence limits 5.40～9. 72mg/kg) in group P, and 3. 14mg/kg (95% confidence limits 2.92～6.10mg/kg) in group SP, Although SBP and MAP prior to intubation was significantly decreased compared with baseline value in group P ( P<0. 05), but no patients suffered clinically significant hypotention or bradycardia in two groups.CONCLUSION The ED₅₀ of propofol for successful intubation without muscle relaxant in children younger than 3 years of age is 4.84(0.28) mg/kg, and 2. 67(0. 18) mg/kg with 5% sevoflurane repectively during induction. Combined inhalation of Sevoflurane, ED₅₀ of propofol for intubation was decreased. A higher induction dose of propofol alone in children than in adults, and no patients suffered clinically significant bradycardia or hypotension of two groups. It was safe that using higher dose of propofol alone to induct in children under 3 years.