Dose-response of remifentanil for tracheal intubation in infants.

To compare the dose-response of remifentanil for tracheal intubation in infants and children, 32 healthy full-term infants and 32 children were anesthetized with 10 mug/kg glycopyrrolate and 4.0 mg/kg propofol and administered 1 of 4 doses of remifentanil (1.25, 1.50, 1.75, or 2.00 microg/kg) to facilitate tracheal intubation. We determined the effective doses of remifentanil in 50% (ED50) and 98% (ED98) of patients by using logistic regression analysis. We found that logistic regression curves were similar for infants and children (P = 0.38). ED50 and ED98 values for remifentanil were 1.70 +/- 0.1 microg/kg and 2.88 +/- 0.5 microg/kg, respectively. In a second double-blind study, 24 infants were anesthetized with propofol and randomized to receive either 3.0 microg/kg remifentanil or 2.0 mg/kg succinylcholine to facilitate tracheal intubation. The duration of apnea, tracheal intubating conditions and hemodynamic changes were determined. We found that the duration of apnea and intubating conditions after propofol/remifentanil were similar to those after propofol/succinylcholine. Bradycardia, hypotension, and chest wall rigidity did not occur. We conclude that the dose-response of remifentanil for tracheal intubation is similar in infants and children. Propofol/remifentanil provides clinically acceptable intubating conditions, stable hemodynamics, and a duration of apnea comparable to that with propofol/succinylcholine in infants.