Evaluation of Clonidine as an Alternative to Fentanyl as Adjuvant in Sub Arachnoid Block in Adults Scheduled for Elective Procedures: A Randomized Controlled Trial

Clonidine and Fentanyl compared as adjuvants in spinal anesthesia

Abstract

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Background: Regional anesthesia is commonly favored for surgeries involving the lower abdomen and lower limbs, as it enables the patient to stay awake and reduces complications linked to airway management. Although hyperbaric bupivacaine 0.5% is widely applied in spinal anesthesia, its major drawback is its limited duration of action. Subarachnoid block with adjuvants such as Clonidine or fentanyl is often administered in lower limb surgeries to extend intraoperative and postoperative analgesia and enhance block quality. This study aimed to compare the onset time of sensory and motor blockade, duration of spinal anaesthesia, and hemodynamic responses between two groups: Group BC (Bupivacaine with Clonidine) and Group BF (Bupivacaine with Fentanyl) in adult patients undergoing elective knee arthroscopy for sports-related injuries. Subjects and Methods: A total of sixty ASA I and II patients, aged 18–50 years, were randomly assigned into two equal groups. Group BC received 12.5 mg bupivacaine combined with 30 µg prediluted Clonidine, while Group BF received 12.5 mg bupivacaine with 25 µg fentanyl. The onset times of sensory and motor block, total duration of spinal anaesthesia, time to two-segment regression and hemodynamic parameters were compared between the two groups. Results: Both groups were comparable in demographic data and ASA classification. The onset of sensory and motor block was slightly faster in Group BC than in Group BF, though the difference was not statistically significant (sensory: 5.61 ± 0.87 vs 5.70 ± 1.14 minutes; motor: 6.21 ± 0.816 vs 6.25 ± 1.15 minutes; p > 0.05). The duration of spinal anesthesia was significantly longer in Group BC (248.66±7.76 minutes) compared with Group BF (230.50±10.53 minutes; p < 0.001). Mean arterial pressure and heart rate remained comparable between groups throughout the procedure. Conclusion: In conclusion, intrathecal Clonidine produces a faster onset of sensory and motor block, a longer duration of spinal anaesthesia, and stable hemodynamic parameters compared to intrathecal fentanyl. Both adjuvants were found to be clinically useful in regional anaesthesia with minimal adverse effects when used in appropriately selected patients.