Comparing lidocaine, bupivacaine and a lidocaine-bupivacaine mixture as a metacarpal block in sheep.

Mechanical sensory blocking effects in the metacarpi of rams were compared following perineural injection of saline, 2% lidocaine (LIDO), 0.5% bupivacaine (BUPI), and a 1:1 (volume/volume) mixture of LIDO-BUPI. Saline was also administered in the contralateral metacarpi. Compared with the saline treatment and contralateral controls, the various treatments induced larger area under the curve (AUC) values 0-60 min post-treatment (AUC0-60). Administration of BUPI and LIDO-BUPI also induced larger AUC60-120 values (P<0.01). The AUC0-60 and AUC60-120 values with LIDO were less than those achieved with LIDO-BUPI and BUPI (P<0.001), and AUC60-120 values with LIDO-BUPI were less than those obtained with BUPI (P<0.05). Anaesthesia occurred within 5 min following the administration of all local anaesthetics and lasted longer in the case of BUPI (110.0 ± 47.3 min) than with LIDO (40.0 ± 13.2 min) (P<0.01). The duration of anaesthesia was 86.9 ± 66.0 min with the LIDO-BUPI combination. Thus this combination offered no apparent advantages over the use of BUPI alone.