Background: Dexmedetomidine, is a imidazole compound, is a pharmacological active of dextroisomer of medetomidine. It is selective and specific to α2A adrenoreceptor, which is responsible for its sedative and analgesic effect. This property has made it popular drug as adjuvant to local anaesthetic drug in regional anaesthesia.

Method: The study was conducted on 60 patients undergoing lower limb orthopaedic surgeries under spinal anaesthesia patients were randomized and allocated into two groups using sealed envelope te hnique based on inclusion and exclusion criteria. All the
patients enrolled for this study were examined preoperatively, and allocated into group I and group II. Group I – 3ml of 0.75% isobaric Ropivacaine. Plus 0.5ml of normal saline. Group II – 3ml of 0.75% isobaric ropivacaine plus 5ug of Dexmedetomidine in 0.5ml of Normal saline.

Result: Time of onset of sensory block was 3.71+0.6min in group I in comparison to 4.94+1.12 min in group II with p value 0.01862. Maximum level of sensory level achieved in group I was T7 and in group II it was T6, with p value 0.0001. Time required to achieve maximum sensory level in group I was 12.6+1.96min, in group II it was 11.62+1.8min, with p value 0.204. Time for two segment regressions was 114.68+16.24min in group 1 but in group II it was 72.42+8.94min with P value 0.00001. Time to regression to S2 segment was 435.64+34.28min in group I and 259.46+26.45 in group II with p value 0.00001.

Discussion and conclusion: Five micro gram of dexmedetomidine when added to ropivacaine is associated with faster onset and longer duration of sensory blocked, haemodynamic stability, absence of sedation and reduced need for analgesia in first 24 hour.