Comparison of Intrathecal Dexmedetomidine and Fentanyl as Adjuvants to Hyperbaric Bupivacaine: A Randomised Controlled Trial

Introduction: Subarachnoid block using bupivacaine along with fentanyl is routinely used in regional anaesthesia technique in lower limb and lower abdominal surgeries. However, fentanyl is often associated with various side effects. The use of dexmedetomidine as an alternative to fentanyl in regional blocks is emerging due to minimal adverse effects and prolonged duration of action. Aim: To compare intrathecal dexmedetomidine and fentanyl as adjuvants to hyperbaric bupivacaine. Materials and Methods: The prospective, randomised study was performed on 100 patients, divided into two groups. Group I patients were administered with bupivacaine 12.5 mg (2.5 mL)+ fentanyl 25 μg (0.5 mL) whereas group II patients received bupivacaine 12.5 mg (2.5 mL) + dexmedetomidine 5 μg (0.5 mL). Post anaesthesia Heart Rate (HR) and Blood Pressure (BP) were recorded. The onset of sensory and motor block, level of sensory block, time for two segment regression, motor and sensor recovery, duration, quality of analgesia and Visual Analog Scale (VAS) score were recorded. Data were analysed using R Studio V 1.2.5001 software. Wilcoxon signed rank test and independent sample t-test were used to find the difference between mean. The p<0.05 was considered statistically significant. Results: Time for onset of sensory block (p=0.0027), motor block (p<0.001) and peak sensory block (p<0.001) was significantly high in group I patients. Most of the patients of group I had a T8 level of sensory block (38%) while in group II around 36% of patients had T6 level of sensory block. Time for full motor recovery (p=0.0015) and sensor recovery (p<0.001) was high in group II patients. Conclusion: Dexmedetomidine is associated with long term motor and sensory block, excellent analgesia and there was less demand for rescue analgesics as compared to fentanyl.