Supraclavicular brachial plexus block: Comparison of varying doses of dexmedetomidine combined with levobupivacaine: A double-blind randomised trial

BACKGROUND AND AIMS: The ideal dose of dexmedetomidine for brachial plexus block is a matter of debate. This study was carried out to evaluate 50 μg or 100 μg of dexmedetomidine added to 0.5% levobupivacaine, with regard to the duration of analgesia. Our study also sought to assess the onset and duration of sensorimotor blockade, haemodynamic effects, sedation and adverse effects. METHODS: One hundred adult patients undergoing upper limb surgeries under supraclavicular brachial plexus block were randomly allocated into two groups. Group LD50 received 29 ml of 0.5% levobupivacaine plus 50 μg of dexmedetomidine diluted in 1 ml of normal saline. Group LD100 received 29 ml of 0.5% levobupivacaine plus 100 μg of dexmedetomidine diluted in 1 ml of normal saline. Duration of analgesia was the primary outcome. Onset and duration of sensorimotor blockade, haemodynamic variables, sedation score, and adverse effects were secondary outcomes. The data were analysed with Students' t-test and Chi-square test. RESULTS: The onset of sensory block and motor block was 14.82 ± 3.8 min and 19.75 ± 6.3 min, respectively, in group LD50, while it was 11.15 ± 1.7 min and 14.3 ± 4.2 min, respectively, in group LD100. The duration of analgesia was significantly prolonged in group LD100 (1033.6 ± 141.6 vs. 776.4 ± 138.6 min; P = 0.001). The incidence of bradycardia and sedation was observed in significantly more patients in group LD100. Significantly fewer patients in group LD100 required rescue analgesia. CONCLUSION: The 100 μg dose of dexmedetomidine in brachial plexus block hastens the onset and prolongs the duration of sensorimotor blockade and analgesia, but with higher incidence of bradycardia and sedation.