A comparative study of the effects of dexmedetomidine added as an adjuvant to bupivacaine, levobupivacaine, and ropivacaine in the brachial plexus blocks: A prospective randomized triple-blind study

Context: Bupivacaine is the most common local anesthetic agent used for brachial plexus blocks (BB). Due to the adverse effects noted with bupivacaine, safer alternative agents such as levobupivacaine and ropivacaine are being used now. Aims: Although several studies exist comparing pairs of anesthetic agents, few studies have compared all three agents using dexmedetomidine (DMT) as an adjuvant. To bridge this knowledge gap, we undertook the present study. Settings and Design: This was a prospective, randomized, placebo-controlled, triple-blind comparative study. Materials and Methods: Eighty patients were randomly allocated to four study groups: group B, given bupivacaine alone, and groups BD, LD, and RD, given twenty-five ml of 0.5% bupivacaine, 0.5% levobupivacaine, and 0.75% ropivacaine, respectively, along with DMT 0.5 μg/kg body weight. Onset of the sensory and motor blocks; duration of the sensory block,motor block and analgesia of the block were compared between the groups. Statistical Analysis Used: Differences between the groups were analyzed using one-way analysis of variance and Tukey's honestly significant difference -β post hoc test for parametric data, and for nonparametric data, Chi-square test and Fisher's exact test were used. Results: The durations of analgesia observed were 7 ± 0.7, 13.4 ± 0.6, 12.7 ± 1.0, and 12.5 ± 0.6 h in groups B, BD, LD, and RD, respectively; these differences were statistically significant (F = 294.825, P < 0.001). Post hoc tests revealed a statistically significant difference between Group B and all the other groups, between the BD and LD groups, and between BD and RD groups. The times to onset of sensory blocks observed were 11.3 ± 11.3, 7.6 ± 0.8, 8.1 ± 0.8, and 8.4 ± 0.8 min in groups B, BD, LD, and RD, respectively, while the times to onset of motor blocks observed were 17.1 ± 1.5, 11.0 ± 0.9, 10.3 ± 1.0, and 10.2 ± 0.7 min in groups B, BD, LD, and RD, respectively. Conclusions: DMT added as an adjuvant to bupivacaine, levobupivacaine, and ropivacaine resulted in a statistically significant enhancement of the duration of analgesia.