Does fentanyl prolong the analgesia of local anaesthetics in brachial plexus block? A randomized controlled study

Abstract

Background: Several adjuvants have been added to enhance the effects of local anaesthetic agents in peripheral nerve blocks. In this randomized controlled study we aimed to assess the effects of addition of fentanyl to local anaesthetics in brachial plexus block with respect to onset time and total duration of analgesia.Methods: In this prospective randomized double- blind study, 40 adult patients of 18-65 years age group were randomly divided into two groups of 20 each. In group L supracavicular brachial plexus block was performed with 30 ml of local anaesthetic solution (10 ml 1.5% lignocaine with adrenaline +20 ml 0.25% bupivacaine) +1ml saline whereas in group LF received the same 30 ml local anaesthetics with 50µg fentanyl in 1ml added to it. The characteristics of block with respect to onset time of sensory and motor blockade, total duration of analgesia and any side effects were evaluated.Results: Both groups were comparable with respect to demographic parameters and duration of surgery. The onset time of complete sensory and motor block was significantly prolonged in group LF (17.2±2.5min and 20.3±2.9min) compared to group L (13.7±3.6min and 17.45±3.7min). The total duration of analgesia was also significantly prolonged (P <0.001) in group LF (374.5±51min) compared to group L (239.25±40.27min). There were no significant side effects noted in any patients in both groups.Conclusions: Addition of fentanyl to local anesthetics in brachial plexus block significantly prolonged the duration of analgesia without any significant side effects though it had delayed the onset of block.