Intravenous regional anesthesia is an easy and reliable anesthetic technique, but its use is limited by tourniquet pain.

Clonidine is effective in overcoming this shortcoming when used with intravenous regional anesthesia at a dose of 1 μg/kg. Dexmedetomidine has also been used successfully at a dose of 0.5 μg/kg.

Based on the potency ratios of clonidine and dexmedetomidine (8 to 1) we hypothesize that a lower dexmedetomidine dose would provide patients with 50 min of pain free tourniquet time.