SMALL-DOSE FENTANYL - OPTIMAL TIME OF INJECTION FOR BLUNTING THE CIRCULATORY RESPONSES TO TRACHEAL INTUBATION

This study was designed to examine the optimal time of injection of a small dose of fentanyl during anesthetic induction to attenuate circul atory responses to laryngoscopy and tracheal intubation. One hundred s eventy patients were randomly assigned to one of five groups. In Group s II, III, IV, and V, patients received fentanyl (2 mu g/kg) 1, 3, 5, or 10 min before tracheal intubation, respectively. Group I patients d id not receive fentanyl and served as the control group. In Groups III and TV, blood pressures were not increased, except diastolic pressure in Group III, significantly postintubation compared with preinduction values; but Groups I, II, and V showed a significant increase (P < 0. 05). The 1-min postintubation values of systolic, diastolic, and mean arterial pressure in Groups III and IV were less than those in the con trol group (P < 0.05). Increases of heart rate in Group IV were less ( P < 0.05) than those in the control group, but significant differences were not observed in Groups II, III, and V. The number of patients wi th tachycardia and dysrhythmia was significantly smaller in Group TV t han in the control group (P < 0.05). We conclude that the most effecti ve time to administer fentanyl to protect circulatory responses to lar yngoscopy and tracheal intubation is 5 min before tracheal intubation. Implications: Fentanyl is often used to reduce the hemodynamic respon se to tracheal intubation. However, large doses may cause unwanted sid e effects. Administration of fentanyl at the optimal time reduces the dose required. Our results indicate that optimal injection time of fen tanyl for intubation is 5 min before intubation.