This randomised, placebo-controlled, double-blind study was designed to assess the effect of intravenous clonidine and magnesium sulphate on intraoperative haemodynamics, anaesthetic consumption and postoperative recovery. Seventy five patients undergoing elective upper limb orthopaedic surgery were randomised into three groups. Group C received clonidine 3 mug/kg as a bolus before induction and 1mug/kg/hour by infusion intraopertively. Group M received magnesium sulphate 30 mg/kg as a bolus before induction and 10 mg/kg/hour by infusion. Group P received same volume of isotonic saline. Anaesthesia was induced and maintained with fentanyl citrate and propofol. Muscular relaxation was achieved by vecuronium bromide. Induction time, recovery time and consumption of propofol as well as fentanyl citrate were recorded. Induction of anaesthesia was rapid with both clonidine and magnesium sulphate. Time of bispectral index (BIS) to reach 60 was significantly lower in Group C and Group M (P < 0.0001). Requirements of propofol and fentanyl were significantly less in Group C and Group M (P < 0.001). Postoperative recovery was slower in Group M compared with other two groups (P < 0.001). Perioperative use of both clonidine and magnesium sulphate significantly reduced the consumption of propofol and fentanyl citrate. Magnesium sulphate caused a delayed recovery.
Keywords: Anaesthetic consumption; bispectral index; clonidine; magnesium sulphate.