A randomised controlled trial of dexmedetomidine for suspension laryngoscopy.

We randomly allocated 80 patients to intravenous dexmedetomidine (0.25, 0.5, or 1 μg.kg(-1) ) or placebo 15 min before anaesthetic induction. Dexmedetomidine 0.5 and 1.0 μg.kg(-1) significantly reduced the mean (95% CI) propofol effect-site concentrations by 0.83 (0.63-1.03) μg.ml(-1) , p = 0.001 and 1.29 (1.12-1.46) μg.ml(-1) , p = 0.0003 at intubation, by 1.05 (0.85-1.25 μg.ml(-1) , p = 0.0006 and 1.33 (1.15-1.51) μg.ml(-1) , p = 0.0002 when surgery started, and by 0.59 (0.39-0.79) μg.ml(-1) , p = 0.030 and 0.72 (0.57-0.87) μg.ml(-1) , p = 0.004 on completion of surgery, respectively. Patients' tracheas were extubated sooner after 0.5 and 1.0 μg.kg(-1) dexmedetomidine, by 5.36 (2.39-8.32) min, p = 0.009 and 7.37 (3.24-11.51) min p = 0.003, respectively. Tachycardic responses to intubation were present in five placebo patients and no dexmedetomidine patients. Bradycardia was treated after dexmedetomidine in six patients: five after 1.0 μg.kg(-1) ; and one after 0.25 μg.kg(-1) . Single-dose dexmedetomidine can reduce anaesthetic requirements, with both desirable and undesirable haemodynamic effects.