Comparison of Intrathecal Dexmedetomidine and Fentanyl as Adjuvants to 0.5% Heavy Ropivacaine for Lower Limb Surgeries: A Randomised Controlled Study

Abstract

Introduction: Spinal Anaesthesia (SA) is a suitable Regional Anaesthesia (RA) for lower limb surgery, but is limited by its comparatively short analgesic duration. Adjuvants like fentanyl and dexmedetomidine can be administered intrathecally with local anaesthetics like ropivacaine to assist in modulating block parameters, extend the duration of analgesia and decrease systemic administration of opioids. Aim: To compare and evaluate the safety and efficacy of intrathecal fentanyl and dexmedetomidine as adjuvants to ropivacaine in lower limb orthopaedic surgery. Materials and Methods: This double-blinded, randomised controlled study was carried out at the Department of Anaesthesiology, Jawaharlal Nehru Medical College, Acharya Vinoba Bhave Rural Hospital, Datta Meghe Institute of Higher Education and Research (DMIHER), Sawangi (Meghe), Wardha, Maharashtra, India. It was performed in 60 American Society of Anaesthesiologists (ASA) I-II patients aged 18-50 years undergoing elective lower limb operations. The patients were divided into two groups: Group-RD was administered 15 mg 0.5% hyperbaric ropivacaine with 10 μg dexmedetomidine and Group-RF was administered 15 mg 0.5% hyperbaric ropivacaine with 20 μg fentanyl. Haemodynamic parameters, sensory and motor block characteristics, sedation {as measured by the Ramsay Sedation Score (RSS)}. Duration of analgesia and sideeffects were recorded. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) v22.0 and GraphPad Prism v6.0 and p<0.05 was considered statistically significant. Results: The mean age was 38.43±8.31 years in GroupRF and 37.27±8.75 years in Group-RD. Group-RD showed a significantly earlier onset of sensory block (4.33±0.64 min vs 5.58±0.59 min). Motor block onset was also earlier in Group-RD (5.04±0.75 min) than in Group-RF (7.57±0.60 min), with a longer motor block duration (207.26±6.58 min vs 148.9±8.22 min). Postoperative analgesia lasted significantly longer in Group-RD (391.86±9.89 min) compared with Group-RF (213.3±3.79 min). Haemodynamic parameters remained clinically stable in both groups, with only slight transient decreases in PR and blood pressure and no significant bradycardia or hypotension. Conclusion: Dexmedetomidine is a better adjuvant to ropivacaine compared to fentanyl in SA. It provides better onset, longer sensory and motor block duration and increased analgesia without inducing further haemodynamic instability or respiratory depression.