Comparative Analysis of the Efficacy of Intrathecal Fentanyl and Magnesium Sulphate as an Adjuvant to Bupivacaine: A Double-Blinded Randomized Controlled Trial.

Backgrounds: The duration and potency of the subarachnoid block (SAB) can be enhanced by incorporating spinal additives into local anesthetics. In this study, the effectiveness of intrathecal fentanyl and magnesium sulphate as adjuvant anesthetics to 0.5% hyperbaric bupivacaine is compared in regard to the onset and duration of sensory and motor block, along with circulatory variables.

Methods: After authorization of ethical committee , 100 patients belonging to American Society of Anesthesiologists grades I and II, were chosen and split into two groups with 50 patients each. A SAB was administered; Group 1 was given 2.5 mL of 0.5% hyperbaric bupivacaine + 0.5 mL of fentanyl (25 μg), and Group 2 received 2.5 mL of 0.5% hyperbaric bupivacaine + 0.2 mL of magnesium sulphate (100 mg). 0.3 mL of distilled water was added to both groups making an intrathecal drug volume of 3.0 mL. Perioperative circulatory parameters and sensory and motor block features are noted and compared. Version 21.0 of Statistical Package for the Social for Windows was used for all statistical calculations.

Results: Group 1 had a faster onset of sensory and motor block in comparison to Group 2. However, both groups were statistically similar with regard to the duration of sensory and motor blockade, visual analog scale scores, intra and postoperative hemodynamic parameters.

Conclusion: 0.5 mL fentanyl functions as a better spinal adjuvant to 0.5% hyperbaric bupivacaine compared to magnesium sulphate, block but both the agents had similar duration of block, postoperative analgesia and hemodynamic parameters.