The optimal dose of remifentanil for acceptable intubating conditions during propofol induction without neuromuscular blockade.

STUDY OBJECTIVE: To determine the optimal remifentanil dose required to provide acceptable intubating conditions following induction of anesthesia with propofol without using neuromuscular blockade. DESIGN: Dose-response study. SETTING: Operating room of a university hospital. PATIENTS: 50 ASA physical status 1 men, aged between 20 and 40 years, who were scheduled for general anesthesia. INTERVENTIONS: Intubating conditions were evaluated according to the scoring system described by Viby-Mogensen et al. Successful intubation was defined as excellent or good. MEASUREMENTS: For induction of anesthesia, an intravenous (IV) bolus dose of propofol 2.0 mg/kg was given over 30 seconds followed by the administration of predetermined IV remifentanil over 30 seconds; intubation was performed 90 seconds after completion of the remifentanil administration. The dose of remifentanil used for each patient was determined by the response of the previously tested patients, using the modified Dixon's up-and-down method (using 0.2 µg/kg as a step size). The first patient was tested with remifentanil 1.0 µg/kg. If intubation failed, the remifentanil dose was increased by 0.2 µg/kg; if intubation was successful, the dose was decreased by 0.2 µg/kg. Mean arterial pressure (MAP), heart rate (HR), and peripheral oxygen saturation were recorded during the study period. MAIN RESULTS: According to probit analysis, the effective dose of remifentanil in 50% (ED(50)) and 95% (ED(95)) of patients were 1.40 µg/kg and 2.40 µg/kg, respectively. Preintubation and postinduction HR and MAP values were lower than preinduction values (P < 0.001). CONCLUSION: The optimal bolus dose of remifentanil for acceptable intubating conditions was 2.40 µg/kg (95% confidence interval, 1.90-9.0 µg/kg) in 95% of patients during induction of anesthesia with propofol 2.0 mg/kg without neuromuscular blocking agents.

Effects of different doses of remifentanil infusion on hemodynamics and recovery in children undergoing pediatric diagnostic cardiac catheterization.

OBJECTIVE: The present study aimed to compare 2 different doses of remifentanil infusion on hemodynamics, recovery period, and complications in children undergoing diagnostic pediatric cardiac catheterization. DESIGN: A prospective study. SETTING: A university hospital. PARTICIPANTS: Children undergoing diagnostic cardiac catheterization (n = 60). INTERVENTIONS: Children (2-12 years of age) scheduled for elective diagnostic cardiac catheterization under sedation were included in this study. The patients were assigned randomly to 2 groups as follows: patients in group 1 (n = 30) received a remifentanil infusion of 0.1 µg/kg/min, and patients in group 2 (n = 30) received a remifentanil infusion of 0.2 µg/kg/min. Heart rate (HR), systolic and diastolic blood pressures (BPs), oxygen saturation (SpO(2)), respiratory rate (RR), sedation, and recovery scores were recorded. MEASUREMENTS AND MAIN RESULTS: There were no significant differences between the groups in terms of systolic and diastolic BPs, HR, SpO(2), and RR during the study period. Additional drugs were required for 15 children in group 1; however, 27 patients maintained a satisfactory level of sedation with the 0.2-µg/kg/min remifentanil infusion. The time to achieve a recovery score of ≥5 was significantly shorter in group 2 than in group 1 (4.1 ± 0.3 minutes v 6.8 ± 0.8 minutes). No postoperative complications were reported in either group. CONCLUSION: After oral midazolam premedication and local prilocaine infiltration, 0.2 µg/kg/min of remifentanil provided adequate sedation without any hemodynamic compromise during pediatric diagnostic cardiac catheterization.