Background
Addition of adjuvants to routinely used intrathecal drugs is cornerstone in safe and effective prolongation of single shot spinal block for gynecological surgery. In resource deficient countries, where epidural anesthesia is usually not used because of cost factor, adjuvants are routinely used to prolong the effect of regional anesthesia. Alpha 2 agonists are considered best drugs as adjuvants, but there is inconclusive data in literature about the block characteristic, dose at which to be used and side effect after use of these drugs.
Methods
Clonidine 30 µgm or dexmedetomidine 5 µgm was used intrathecally as an adjuvant with 15 mg bupivacaine 0.5% in 90 female patients undergoing gynecological surgery in this randomized, prospective, single blind study.
Results
The mean time to onset of sensory block a (T6 level) and time to attain maximum sensory height were significantly early in group D over group C (124.44 ± 20.64 s, 175.09 ± 68.01 s,  < 0.0001) and (13.53 ± 2.97 min, 18.64 ± 4.82 min,  < 0.0001)respectively. Time to two segment sensory regression, total duration of analgesia, duration of motor blockade was (115.24 ± 8.9 min, 370.60 ± 17.98 min, 316.67 ± 21.39 min) in group D and (103.58 ± 11.25 min, 323.91 ± 23 min, 273.51 ± 18.95 min) in group C respectively ( < 0.001). The post-operative visual analogue scale score (VAS) was more in group C at 240 min onwards ( ≤ 0.01). Analgesic use and intraoperative complications were similar in both the groups. ( > 0.05).
Conclusions
We recommend clonidine 30 µg over dexmedetomidine 5 µg as an adjuvant to intrathecal bupivacaine, to effectively and safely prolong the effect of single shot spinal anesthesia.