Analgesic Efficacy and Sedative Effect of Dexmedetomidine Versus Clonidine as an Adjuvant to Epidural Ropivacaine in Lower Limb Surgery: A Comparative Study

Abstract

BACKGROUND Epidural anaesthesia is widely accepted for lower limb surgery in terms of avoidance of laryngoscopic surge, better perioperative pain management, greater patient satisfaction and attenuation of neuroendocrine response to surgery. Among many drugs, α₂adrenergic agonist has been used widely as an adjuvant to local anaesthetics due to its better analgesic and sedative property without significant respiratory depression. The aim of this study was to compare the analgesic and sedative effects of dexmedetomidine and clonidine in epidural anaesthesia. MATERIALS AND METHODS 86 patients of either sex aged 40-65 years and body weight of 40-70 Kgs of ASA class I-II, posted for elective lower limb orthopaedic surgeries were randomly allocated in two equal groups either to have 0.75% ropivacaine and dexmedetomidine (group RD) or 0.75% ropivacaine and clonidine (group RC) and were observed regarding block characteristics in term of onset and duration for maximum sensory level achieved, time to complete motor block ,intraoperative and postoperative sedation level, time to two segment regression of sensory block, time to first analgesic requirement, hemodynamic stability and adverse effects. Postoperative epidural top-up dose of 8 ml 0.2% ropivacaine was used as rescue analgesia. Observed data were tabulated in the Excel sheet and analysed with SPSS for windows (Version 12.0). Categorical data are presented as percentage of number of patients [n (%)]; continuous data are expressed as mean ± SD. Statistical analysis was done using independent samples t test (continuous data) and Chi-square test (Categorical data). A 'p' value <0.05 has been considered as statistically significant. RESULTS Onset of sensory and complete motor block and time to reach maximum sensory block was earlier in dexmedetomidine group (p<0.05). Mean time to two segment regression of sensory block and first rescue analgesia was longer in dexmedetomidine group (p<0.05). Intraoperative sedation was more in dexmedetomidine group (p<0.05). Other variables are comparable in both groups. CONCLUSION Dexmedetomidine has earlier onset of sensory and motor block, provides longer duration of analgesia and better intraoperative sedation than clonidine when administered as an adjuvant in epidural anaesthesia.