This study was conducted to evaluate the effects of fentanyl and midazolam when used as adjuvant in a supraclavicular brachial plexus block.

100 adult patients with an ASA status of I-II that were scheduled to undergo upper extremity surgery performed under a supraclavicular brachial plexus block were prospectively evaluated in this study. The patients were randomly divided into 4 study groups: Group 1, which received 40 ml of 1.5% lidocaine, Group 2, which received 3 mg of midazolam with 40 ml of 1.5% lidocaine, Group 3, which received 100 µg of fentanyl with 40 ml of 1.5% lidocaine, and Group 4, which received 3 mg of midazolam and 100 µg of fentanyl with 40 ml of 1.5% lidocaine. The onset time, as well as the duration of analgesia and motor blocks, proportion of successful blocks, hemodynamic parameters, and adverse events were then noted.

The incidence of successful block was higher in group 4 (92%) than in any other groups (68-72%) (P = 0.185). In addition, the mean duration of analgesia was longer in groups 2 and 4 (165 min and 175 min) than in groups 1 and 3 (114 min and 131 min) (P < 0.05). Furthermore, the mean duration of motor block was longer in groups 2 and 4 (169 min and 180 min) than in groups 1 and 3 (123 min and 126 min) (P < 0.05). No significant difference was observed in the onset time of the sensory block and motor block when the groups were compared.

Although the addition of 3 mg of midazolam and 100 µg of fentanyl to lidocaine in a supraclavicular brachial plexus block does not affect the onset of sensory or motor block, it does prolong the duration of analgesia and motor block.