Lidocaine concentrations associated with intravenous regional anesthesia of the distal limb of cattle.

Cannulation for injection of lidocaine HCl was done in 3 distal veins in the hindlimb of 5 young Friesian cattle maintained in a light plane of general anesthesia. The local and systemic plasma and tibiotarsal joint synovial fluid concentrations of lidocaine (British lignocaine) were estimated for 60 minutes after the drug (10 ml, 2% (w/v)) was injected into the veins distal to a tourniquet. The lidocaine concentration in the distal veins was high but variable initially, and fell markedly over the 60 minutes. The systemic circulation always had a low but measurable concentration of lidocaine that became slightly higher in the 5 minutes after tourniquet release. According to the concentrations found, the risk of toxicity of lidocaine by using this technique in clinical practice would appear negligible.