Tramadol as an adjuvant to lidocaine for axillary brachial plexus block.

BACKGROUND: In this prospective randomized study, we evaluated the effect of tramadol as an adjuvant to axillary block.

METHODS: We studied 102 patients scheduled for hand surgery under axillary block with lidocaine 1.5% (epinephrine 1/200,000) and the addition of either 4 mL saline (control group), 100 mg tramadol and 2 mL saline (TL group), or 200 mg tramadol (TH group).

RESULTS: Onset time was longer in the TH group, 16 +/- 7 min (9 +/- 3 min in control group; P = 0.01). Sensory block and time for first rescue analgesia were significantly prolonged in the TH group compared with both TL and control groups (265 +/- 119 min vs 190 +/- 87 min vs 126 +/- 48 min; P = 0.018); (734 +/- 434 min vs 573 +/- 516 min vs 375 +/- 316 min; P = 0.02).

CONCLUSIONS: The benefit of block prolongation associated with the addition of 200 mg tramadol to lidocaine during axillary block is limited by the slow onset of the block.