Controlled hypotensive anaesthesia is very useful in mastoid surgery using operating microscope to obtain a good surgical field. This study compares two methods of maintaining controlled heart rate and blood pressure.

Methods: There were 2 groups, D and P of 35 patients each. General anaesthesia was induced by a common protocol. In group D, dexmedetomidine bolus (0.2 mcg/kg) at induction and infusion (0.2 mcg/kg/h) were given. In group P, propofol boluses (1 mg/kg) were used to maintain hypotension. Target mean arterial pressure (MAP) was 55- 65 mm Hg and target heart rate 60 -75 beats per minute. Parameters noted were heart rate and blood pressure (systolic, diastolic, mean), need of other interventions to maintain heart rate ( beta blocker or atropine) and blood pressure (vasopressor, increasing concentration of inhalational agent), intraoperative bleeding score and recovery room parameters (pain, shivering, nausea and vomiting)

Results & Discussion : Both arms maintained MAP within the target range. Dexmedetomidine at dose of 0.2 mcg/kg bolus and infusion, is equally efficacious as Propofol boluses in maintaining mean arterial pressure within a range of 55 – 65 mm Hg. Heart rate control (60-75 per minute) was better in dexmedetomidine group, requiring significantly lesser amount of beta blocker than propofol. Use of  Dexmedetomidine, even in such a lower dose, significantly reduced the requirement of inhalational agent. Dexmedetomidine did not increase incidence of postoperative sedation or postoperative nausea and vomiting.

Conclusions: Dexmedetomidine at a dose of 0.2 mcg/kg bolus and infusion, is equally efficacious as propofol boluses in maintaining mean arterial pressure within a range of 55 – 65 mm Hg. Heart rate control was better in dexmedetomidine group, requiring significantly lesser amount of beta blocker than propofol. Use of  Dexmedetomidine, even at this lower dose, significantly reduced the requirement of inhalational agent without increasing the incidence of sedation or postoperative nausea and vomiting.