Refined induction of anesthesia with remifentanil after bolus propofol administration in Landrace/Large White swine

The authors report a prospective randomized blind study in which they used a refined anesthetic technique in male Landrace/Large White swine (n = 125 pigs, 19 +/- 2 kg, 10-15 weeks old). The animals were first premedicated with ketamine, midazolam and atropine and then given a dose of 1, 2, 3, 4 or 5 mu g remifentanil per kg body weight (dose amounts were randomly assigned) after a bolus dose of propofol. The authors assessed the intubation conditions (e.g., jaw relaxation and other parameters) 20 min after premedication and then 5 min after anesthesia induction. All animals that received each of the different remifentanil dose amounts were successfully intubated in less than 30 s. No animal developed apnea during intubation or experienced substantial reductions in heart rate or blood pressure (>25%) between the two time points (20 min after premedication and 5 min after anesthesia induction). Overall intubation conditions were significantly better in animals that received 5 mu g remifentanil per kg body weight than in animals that received other dose amounts (P < 0.001). The average time to intubation was significantly shorter for animals that received 5 mu g remifentanil per kg body weight than for animals that received any of the other dose amounts (P < 0.001). The authors concluded that for this study, 5 mu g remifentanil per kg body weight resulted in excellent intubating conditions in this swine breed.