Introduction: Spinal anaesthesia is the anesthesia of choice for patients undergoing lower abdominal and lower limb surgeries. However its use is restricted by the limited duration of its action.
Aim: To study the comparative evaluation of clinical efficacy of dexmedetomidine when used either by intravenous or intrathecal route in patients undergoing surgeries under spinal anaesthesia.
Materials and Methods: 60 American Society of Anaesthesiologists Grade I and II were randomized to receive dexmedetomidine by either intravenous (0.5µgm/kg) (Group I) or intrathecal (0.5µgm) (Group II) routes, in patients scheduled for surgeries under spinal anaesthesia. Primary outcomes studied were the duration of sensory and motor blocks. Secondary outcomes were the time for first request of analgesia, sedation levels and incidence of bradycardia and hypotension.
Results: Group II patients showed significant prolongation of sensory and motor block as compared to Group I (p= 0.009, ˂0.000 respectively). Similarly the time of rescue analgesia is greater in Group II (p= 0.0001). However mean sedation levels were greater in Group I (p=0.02). There was no significant difference in the incidence of bradycardia and hypotension between two groups.
Conclusion: Intrathecal dexmedetomidine as an adjuvant in spinal anaesthesia, showed significant prolongation of duration of sensory and motor blocks as compared to its intravenous counterpart, without significant increase in incidence of adverse effects.

Keywords: Dexmedetomidine, Intravenous, Intrathecal, Adjuvant, Spinal anaesthesia.