Introduction: The versatility of spinal anaesthesia is afforded by a wide range of local anaesthetics and additives that allow control over the level, the time of onset and the duration of spinal anaesthesia. The present study was conducted to compare the effects of isobaric ropivacaine 0.5% with and without dexmedetomidine 5 mcg in spinal anaesthesia in lower limb and perineal surgeries in terms of the onset of sensory and motor block, duration of sensory and motor block, and duration of analgesia.
Material and Methods: In this prospective randomized double blind study, 60 patients of physical status ASA I & II scheduled for lower limb and perineal surgeries under the subarachnoid block were randomized to receive either intrathecal 3 ml of 0.5% isobaric ropivacaine with 0.05 ml of 5 mcg preservative dexmedetomidine (Group RD, n=30) or 3 ml of 0.5% isobaric ropivacaine with 1 ml of normal saline (Group R, n=30). Onset of sensory block, maximum level of sensory block, time taken to achieve maximum sensory level and duration of sensory block was noted. The degree of motor block was assessed every 5 min for first 30 min and then every 15 min till completion of surgery.
Results: The mean time for onset of sensory block was 8.23±2.91 min in Group
RD and 8.76 ± 2.97 min in Group R. The mean time for onset of motor block in group RD was 11.8±2.52min and 12.46 ± 2.51 min in group R. The mean duration of sensory block was prolonged (191.03±32.97min) in group RD than group R (169.13±30.98 min). The mean duration of motor block was also prolonged in group RD than group R (4.41±0.49 hrs vs 3.6 ±0.55 hrs The mean duration of analgesia was 7.52 ± 2.10 hrs in group RD and4.25 ± 1.80 hrs in group R. Hypotension was observed in 4 (13.33%) patients in group RD and in (6.66%) patients of group R. Bradycardia was observed in 2 (6.66%) patients from both the groups.
Conclusion: We conclude that Dexmedetomidine as an adjunct to 0.5% Ropivacaine is superior to 0.5% Ropivacaine alone in spinal anaesthesia. It augments the onset and duration of sensory and motor block, as well as total duration of analgesia thus, reducing the requirement of analgesics in postoperative period.