Anesthésie et recherche clinique
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Optimization of Bupivacaine Induced Subarachnoid Block by Clonidine: Effect of Different Doses of Oral Clonidine

Mamta Harjai, Jaishri Bogra, Rajni Gupta, Gurumoorthi R, Girish Chandra, Prithvi Kr Singh and Pratima Srivastava

Background: Various drugs are used for premedication to reduce anxiety and to provide hemodynamic stability. The study was designed to investigate the optimum dose of oral clonidine administered preoperatively with regard to its anxiolytic efficacy and its effect on hemodynamics and sedation. We studied the effect of three different doses of oral clonidine on surgeries below umbilicus which were administered intrathecal bupivacaine.

Methods: A placebo controlled double blind study was conducted on 120 patients scheduled for surgeries below umbilicus. Group 1 received oral placebo, group 2 received oral clonidine 3 μg kg-1, group 3 received oral clonidine 4 μg kg-1 and group 4 received oral clonidine 5 μg kg-1 along with 0.5% heavy bupivacaine 0.3 μg kg-1 intrathecally in each group. Outcomes assessed were anxiolysis through VAS, level of sensory block, time to reach highest sensory segment, regression to L1 segment, sedation score, bradycardia and hypotension.

Results: There was improved block duration and sedation with the different doses of clonidine. Time for the sensory block to regress to L1 and rescue analgesia was longest in 4 followed by groups 3 and 2. There was significant dose dependent decrease in VAS anxiety score between group 1 and other clonidine groups in intraoperative and post-operative period. However, the episodes of bradycardia and hypotension were highest in 4 group.

Conclusion: Preoperative oral clonidine 4 μg kg-1 appears to be the optimum dose for optimization of spinal anaesthesia with bupivacaine as it prolongs the sensory block maximally with minimal side effects.