Abstract

Clonidine and dexmedetomidine have been repeatedly demonstrated to prolong sensory and motor block when used intrathecally with local anaesthetics. Clonidine and dexmedetomidine have also been known to affect blood pressure in a complex fashion after intrathecal administration, because of opposing actions at multiple sites. The present study was planned to compare the effects of dexmedetomidine and clonidine on duration of analgesia, motor and sensory blockade and the intraoperative hemodynamic profile when used as an adjuvant to bupivacaine. Methods: This was a unicentric prospective randomized, single blinded, observational study done in Department of Anaesthesiology, Calcutta National Medical College in association with Urology, orthopaedic and gynaecology & obstetrics during February, 2012 to March, 2013. Groups were designated according to the study drug received, as follows: Group D- received 2.6 ml of hyperbaric bupivacaine (13 mg) and 5 μg of dexmedetomidine (0.05 ml) and 0.35 ml of normal saline and Group C- received 2.6 ml of hyperbaric bupivacaine (13 mg), 37.5 μg of clonidine (0.25ml) and 0.15 ml normal saline. Any incidence of adverse effects in the intraoperative or immediate postoperative period were noted and again patients were followed up at 24 hours in the ward for incidence of nausea, vomiting or any other adverse reaction. Results: In our study, maximum surgery performed were lower limb orthopaedic surgery (35%), then TURP (23.33%), then vaginal hysterectomy (21.66%) and total abdominal hysterectomy (20%). In group-C patients time for 2 segment regression was 125.5±13.35 minutes and in group-D patients higher (157±11.64 minutes). So, it can be said that both clonidine and dexmedetomidine prolongs the 2-segment regression time but dexmedetomidine is superior in prolonging 2 segment regression time. In group-C patients S1 regression time was 247.5±23.22 minutes and in group-D patients higher (303±25.66 minutes). So, it can be said that both clonidine and dexmedetomidine prolongs the time for regression to S1 level but dexmedetomidine is better alternative in prolonging the time for regression to S1 level. Group-C patients took 217.5±23.55 minutes to regain Bromage score 0 and group-D patients took 260.5±20.27 minutes. So, motor blockade was also prolonged in dexmedetomidine group than in clonidine group. Conclusion: In equipotent doses dexmedetomidine is more effective as intrathecal adjuvant to hyperbaric bupivacaine than clonidine. Neither clonidine nor dexmedetomidine increases side-effects of spinally administered hyperbaric bupivacaine if given in appropriate doses

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