Controlled hypotension for FESS: A randomised double-blinded comparison of magnesium sulphate and dexmedetomidine

Background and Aims: Intense bleeding during general anaesthesia (GA) is the major limitation during functional endoscopic sinus surgery (FESS). This study was aimed to compare the efficacy of dexmedetomidine and magnesium sulphate (MgSO4) for controlled hypotension in FESS. Methods: Sixty eight patients undergoing FESS were randomised to receive either dexmedetomidine 1 mu g/kg over 10 min followed by infusion at 0.2 to 0.7 mu g/kg/h (Group D) or MgSO4 40 mg/kg over 10 min followed by an infusion at 10 to 15 mg/kg/h (Group M). Anaesthesia and infusion rates for study drugs were maintained with sevoflurane to keep MAP between 60-70 mmHg throughout the surgery. The time to reach the target MAP, the number of patients requiring a minimum and maximum infusion doses of study drugs were noted. Results: The mean time to achieve target mean arterial pressure (MAP) was less in group D (10.59 +/- 2.04) as compared with (21.32 +/- 4.65 min) group M (P < 0.001). The target MAP was achieved between 5-15 min in 73.52% patients (Group D) with an infusion dose of 0.2-0.4 mu g/kg/h of dexmedetomidine without the use of sevoflurane, while 82.35% patients in group M required 4% sevoflurane along with >12-15 mg/kg/hr infusion of MgSO4 to achieve target MAP in 10-20 min. Conclusion: Dexmedetomidine is superior to MgSO4 in achieving target MAP in lesser time with minimum infusion dose.