Comparison of morphine, dexmedetomidine and dexamethasone as an adjuvant to ropivacaine in ultrasound-guided supraclavicular brachial plexus block for postoperative analgesia-a randomized controlled trial.

Background And Aims: An ideal adjuvant to local anesthetic in a nerve block should prolong the duration of analgesia, and hasten the onset of sensory and motor blockade without significant adverse effects. The aim of this study was to compare morphine, dexmedetomidine, and dexamethasone as an additive to ropivacaine in ultrasound-guided supraclavicular brachial plexus block (SBPB) for postoperative analgesia.

Material And Methods: In this randomized, double-blinded study, 150 patients undergoing upper extremity surgery were randomly divided into three groups: group A (morphine 5 mg), group B (dexmedetomidine 50 μg), and group C (dexamethasone 8 mg). The additives were added to 30 ml of 0.5% ropivacaine solution and administered in SBPB. The duration of postoperative analgesia, onset of sensory and motor blockade, sedation, and adverse effects were observed. The pain was assessed by visual analog scale (VAS) and sedation by Ramsay sedation score. The duration of postoperative analgesia was taken as time consumed from block completion to administration of rescue analgesia (VAS >3).

Results: The demographic profile was similar in both groups. The duration of analgesia was significantly longer in dexamethasone (867.2 ± 217.6 min) than morphine (739. 2 ± 162.5 min) and dexmedetomidine (654.2 ± 179.9 min) ( < 0.001). The onset of sensory and motor blockade was quicker with dexmedetomidine than dexamethasone and morphine. Three cases of block failure were reported with morphine. No major adverse effects were reported.

Conclusion: Dexamethasone is an ideal adjuvant to ropivacaine in brachial plexus block to prolong postoperative analgesia and devoid of adverse effects. Dexmedetomidine has a quicker onset of sensory and motor blockade.