ABSTRACT : This study was designed to find out the dose of dexmedetomidine (DMT) which provides meaningful analgesia without prolonging motor block.

METHODS : 50 patients of ASA I and II scheduled for elective perianal surgeries were randomly allocated into two groups C and D (n = 25) in this prospective double blind study. GroupD received hyperbaric bupivacaine 0.5% (4 mg) + DMT 5 µg and groupC received hyperbaric bupivacaine 0.5% (4 mg) + DMT 3 mcg intrathecally (volume made to 1 ml with normal saline in both groups). Haemodynamics, Onset of sensory block at S1, duration of analgesia, pain scores, sedation scale, time for ambulation, total duration of sensory and motor blockade, time for first urination were recorded.

RESULTS : Demographic characteristics were comparable. Onset of sensory block to S1 was 9.61 ± 5.53 min in group C compared to 7.69 ± 4.80 min in group D (p – 0.35). Duration of sensory (145.28 ± 83.17 min – C, 167.85 ± 93.75 min – D, p – 0.5) and motor block ( 170.53 ± 73.44 min – C, 196.14 ± 84.28 min, p – 0.39) were comparable. Duration of analgesia( 337.86 ± 105.11 min – C, 340.78 ± 101.81 min – D, p – 0.9) and time for ambulation ( 252.46 ± 93.72 min – C, 253.64 ± 88.04 min – D, p – 0.97)were also comparable. 1 patient in each group had urinary retention requiring catheterization.

CONCLUSIONS :Intrathecaldexmedetomidine 3 micrograms doesnot produce faster ambulation compared to intrathecaldexmedetomidine 5 micrograms, though it produces comparable duration of analgesia for perianal surgeries.