No sedative anesthetic was used in group A ; In group B , Dex 0.3 g/kg intravenously for initial bolus ( duration 15 min ) and then 0.3 gkg ( -1 ) h ( -1 ) continuous infusion ; In group C , Dex 0.5 g/kg intravenously ( duration 15 min ) for initial load and then 0.3 gkg ( -1 ) h ( -1 ) continuous infusion .