Abstract

Unless contraindicated, spinal anaesthesia is the preferred mode of anaesthesia in patients undergoing surgeries of lower limbs. Used alone in spinal anaesthesia, hyperbaric bupivacaine 0.5% is associated with relatively short duration of action leading to the need to rescue with general anaesthesia if the surgical procedure exceeds beyond the drug’s duration of action. Over the years many drugs have been used as an additive to spinal anaesthesia in order to hasten its onset of action, decrease the time to surgical incision, prolong the duration of action and to provide adequate postoperative analgesia. Materials and Methods: This prospective randomized double blind study was conducted with 180 consenting patients of ASA grade I and II, scheduled for lower limb orthopaedic surgeries. Using the sealed envelope method, the patients were randomly allotted into 3 groups, 60 patients in each group. Group BS, Group BD1, Group BD2. The surgeon, patient and the observing anaesthesiologist were blinded to the patient group. All patients received drug volume of 3 ml containing 2.5 ml (12.5 mg) hyperbaric bupivacaine hydrochloride. The study groups received dexmedetomidine 5 μg (group BD1) or 10 μg (BD2) diluted to 0.5ml with 0.9% saline, added to bupivacaine in the same syringe. The control group BS received an identical volume of 0.9% saline added to bupivacaine. Standard monitoring with non-invasive BP, HR and ECG were started. Results: 180 patients were enrolled into the study. The groups were comparable with respect to age, weight, height, effect distribution and operative time. Sedation score and hemodynamic data did not differ significantly among the groups. The duration of sensory block was significantly prolonged in the group receiving intrathecal dexmedetomidine as adjuvant as compare to the group receiving local anaesthetic alone. The mean sensory block duration in BD1 group and BD2 was significantly prolonged. Conclusion: Supplementation of spinal bupivacaine with dexmedetomidine significantly prolonged both sensory and motor block compared with intrathecal bupivacaine alone. Patients in the groups that received dexmedetomidine had reduced post-operative pain scores and a longer analgesic duration than those who received spinal bupivacaine alone

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