The effects of DEX premedication on volatile induction of mask anesthesia (VIMA) and sevoflurane requirements

We investigated the effect of intravenous premedication with single dose of dexmedetomidine (DEX) on volatile anesthetic induction time and sevoflurane requirements of anesthesia maintenance in adults by monitoring the bispectral index (BIS). Sixty adult patients with status of ASA I–II undergoing general anesthesia with endotracheal intubation were randomly divided into two groups: The first group; a control group (group C, n = 30) and the second group; DEX group (group D, n = 30). Each patient in group D was premedicated with intravenous DEX 0.5 μg/kg or placebo 10 min before the induction of anesthesia. Anesthesia was induced by fentanyl 1 μg/kg, 1:1 ratio of nitrous oxide and oxygen and sevoflurane of 5–8 % and rocuronium bromur (Esmeron) 0.5 mg/kg keeping BIS values at 40–50. Time to induction of anesthesia, BIS, End-tidal sevoflurane concentration (Et_sevoflurane), End-tidal CO₂ concentration, duration of surgery, recovery time, hemodynamic variables, adverse effects were recorded intraoperatively. Analgesic requirement was noted in postoperative 24 h-period. The time to induction of anesthesia (p < 0.0001) and Et_sevoflurane at 1 min (p < 0.05) were significantly lower in group D than in group C. Intravenous premedication with 0.5 μg/kg of DEX decreased the induction time by almost 75 % and provided a significant decrease in Et_sevoflurane.