Comparison of Two Doses of Intrathecal Dexmedetomidine as an Adjuvant to Hyperbaric Ropivacaine in Infraumbilical Surgeries: A Double-blinded Randomised Clinical Study

Introduction: Spinal anaesthesia is widely used for infraumbilical surgeries because of its rapid onset and reliable block characteristics. Dexmedetomidine has emerged as an effective intrathecal adjuvant, but the optimal low dose when combined with hyperbaric ropivacaine remains uncertain. Aim: To compare the efficacy and safety of 2 µg versus 4 µg intrathecal dexmedetomidine as an adjuvant to 0.75% hyperbaric ropivacaine in patients undergoing infraumbilical surgeries. Materials and Methods: A double-blinded randomised clinical study was conducted at Jhalawar Medical College, Jhalawar, Rajasthan, India on 64 American Society of Anaesthesiologists (ASA) physical status I-II patients aged 30-65 years undergoing elective infraumbilical surgeries under spinal anaesthesia. Patients were randomly allocated into two groups (n=32 each). Group A received 0.75% hyperbaric ropivacaine with 2 µg dexmedetomidine, while Group B received 0.75% hyperbaric ropivacaine with 4 µg dexmedetomidine intrathecally. The primary outcomes were time to first rescue analgesia and number of rescue analgesic doses within 24 hours. Secondary outcomes included onset and duration of sensory and motor block, haemodynamic parameters, postoperative pain scores, sedation score, and adverse effects. Continuous variables were analysed using the independent Student’s t-test, categorical variables using the Chi-square test or Fisher’s exact test, and postoperative Visual Analogue Scale (VAS) and Ramsay Sedation Scores (RSS) using the Mann-Whitney U test. A p-value <0.05 was considered statistically significant. Results: A total of 64 patients were analysed (32 per group). Sensory and motor block onset was significantly faster in Group B than Group A (3.41±0.65 vs 4.62±0.78 and 4.95±0.72 vs 6.12±0.84 minutes, respectively; p-value <0.001), while their duration was significantly longer (218.76±20.41 vs 162.45±18.32 and 186.94±18.28 vs 138.62±16.75 minutes, respectively; p-value <0.001). Time to first rescue analgesia was longer (356.82±32.15 vs 228.54±24.76 minutes; p-value <0.001) and rescue analgesic requirement was lower in Group B (1.42±0.49 vs 2.38±0.56 doses; p-value <0.001). VAS scores were significantly lower in Group B at 2, 4, and 6 hours (p-value =0.003, p-value <0.001, and p-value <0.001, respectively). RSS and adverse effects were comparable (p-value >0.05). Conclusion: Intrathecal dexmedetomidine 4 µg with 0.75% hyperbaric ropivacaine prolonged sensory and motor blockade and postoperative analgesia, and reduced rescue analgesic requirement compared with 2 µg, without a significant increase in adverse effects.