What is an Optimal Dosage of Alfentanil for Minimizing the Hemodynamic Change to Endotracheal Intubation during Anesthesia Induction with Propofol Target-Controlled Infusion?

Background: Laryngoscopy and tracheal intubation are associated with hemodynamic pressor responses, which can have adverse effects. During anesthesia induction with propofol target-controlled infusion (TCI), we aimed to determine the most appropriate dosage of alfentanil required for intubation, using a steady effect-site concentration of propofol and with the use of vecuronium. Methods: Eighty ASA class 1 or 2 patients presenting for elective surgery were allocated at random to one of four groups. Anesthesia was induced in all patients with TCI of propofol target concentration 8/ml, followed by vecuronium (0.12 mg/kg). This was reduced to 5/ml when the effect-site concentration had been 4/ml. After the effect-site concentrations had reached to 5/ml, control group received normal saline, group 1 received alfentanil 10/kg, group 2 received alfentanil 20/kg, and group 3 received alfentanil 30/kg. Laryngoscopy and intubation were performed 90 s later. Heart rate was monitored continuously. Systolic blood pressure, diastolic blood pressure and mean arterial pressure were measured at pre-induction, post-induction (pre-intubation) and post-intubation, respectively. Complications such as hypotention and bradycardia were recorded until 5 minutes had elapsed after tracheal intubation. Results: Control group showed significant increases associated with tracheal intubation in all hemodynamic variables (P /kg constitutes the optimal dosage to obtund the hemodynamic responses to tracheal intubation, using propofol TCI (5/ml) and vecuronium for induction of anesthesia.