Mepivacaine as an intravenous regional block interferes with reactive hyperemia and decreases steady-state blood flow.

Abstract

Background and objectives: Local anesthetics block propagation in nerve fibers but may also inhibit inflammation. Inflammatory phenomena such as warmth, reddening, and swelling are intimately connected with blood flow. Our primary aim was to investigate the effect of mepivacaine on cutaneous blood flow in a situation involving hyperemia, but no inflammation, namely, after arterial occlusion.

Methods: The subjects were healthy volunteers (9 men, 7 women). Pain was evaluated by visual analog scale every 5 minutes. A laser Doppler probe was applied on each forearm. After baseline flow measurements during 30 minutes, a bilateral regional intravenous block (Bier block) was performed by injecting mepivacaine (1.4 mg/kg in 40 mL) in one arm and normal saline in the other in a randomized, controlled, double-blind manner. Arterial occlusion was maintained for 20 minutes, and flow was followed for 60 minutes after release of the block.

Results: The ischemic pain, though modest, was less (P = .045) in the treated arm. Following release of the cuff, the blood flow had essentially stabilized after 20 minutes. The reactive hyperemia (1-20 minutes) was attenuated in the mepivacaine-treated arm (mean, 68% of placebo, P = .025). In the 21-60-minute period, flow in this arm stabilized at a lower level (mean, 73% of placebo, P = .0013).

Conclusion: Mepivacaine is a vasoconstrictor of long duration. This has to be taken into account when antiinflammatory effects of mepivacaine are assessed.