Comparison of Fentanyl vs. Nalbuphine as Adjuvants to Bupivacaine for Spinal Anesthesia in Elective C-Sections

Abstract

Introduction: Spinal anesthesia is widely used for lower segment caesarean sections (LSCS) due to its effectiveness and minimal motor blockade, facilitating faster recovery. Bupivacaine, commonly used for spinal anesthesia, can have limitations like hypotension and a short duration of action. Adjuvants such as fentanyl and nalbuphine are often added to enhance the anaesthetic effect and prolong pain relief while minimizing side effects.

Objective: The study aims to compare the efficacy of fentanyl versus nalbuphine as adjuvants to 0.5% bupivacaine for spinal anesthesia in LSCS, focusing on analgesic duration, sensory and motor block onset, and adverse effects.

Methods: This prospective, randomized controlled study included 80 ASA I and II full-term parturient women undergoing elective LSCS. Patients were divided into two groups: Group BF received 0.5% bupivacaine with 12.5 µg fentanyl, while Group BN received 0.5% bupivacaine with 0.8 mg nalbuphine. Onset and duration of sensory and motor blockade, duration of analgesia, and adverse events were recorded and analysed using the Mann-Whitney U test for continuous variables and Fisher exact test for categorical variables.

Results: The duration of analgesia was significantly longer in Group BN (154.8 ± 8.3 min) compared to Group BF (148.1 ± 7.1 min) (p<0.05). The onset of sensory block was similar in both groups (p=0.0533), while the time to two-segment regression was longer in Group BF (97.8 ± 4.8 min) compared to Group BN (92.3 ± 3.4 min) (p<0.0001). No significant differences were found in motor block onset or adverse events between the groups.

Conclusion: Both fentanyl and nalbuphine, when used as adjuvants to bupivacaine, are effective in enhancing spinal anesthesia during LSCS. Nalbuphine provides longer postoperative analgesia with fewer side effects, making it a favourable alternative to fentanyl.