Bupivacaine 0,25% versus ropivacaine 0,25% in brachial plexus block in dogs of beagle breed

Abstract

The brachial plexus block (BPB) is a regional anesthesia technique which enables the attainment of surgical procedures distal scapulohumeral articulation. This study aimed to compare the efficacy of ropivacaine and bupivacaine 0.25% without vasoconstrictor in BPB guided by electrical stimulation in dogs. Thirteen male and female beagle dogs underwent a BPB using bupivacaine and ropivacaine 0.25% (4mg/kg), both alone and in different times. The anesthesic block was performed in the right forelimb  and as control group the block proceeded in the left forelimb using a solution of sodium chloride 0.9% in volume corresponding to the drug in the contralateral limb. The block was performed after the localization of the radial nerve with the aid of eletrical stimulation, which was infiltrated half the volume of anesthetic calculated and subsequently the remaining solution was administered on the median nerve. We evaluated sensitive and motor latencies and sensitive and motor block total time by clamping technique. In the present study, a technique for electrical stimulation was effective in 100% of animals. Bupivacaine had lower motor latency period, however, the sensitive latency between the two groups showed no statistically significant differences. In the block total time, bupivacaine obtained time significantly higher. Clinical signs characteristic of Horner’s syndrome were present in 15% of animals treated with bupivacaine. Furthermore, two animals presented signs of cardiotoxicity in bupivacaine group. The use of bupivacaine (4mg/kg) without vasoconstrictor in dogs brachial plexus block provided longer analgesia and motor blockade, however, ropivacaine at the same dose and concentration was found to be free of deleterious effects associated of cardiovascular instability, hemodynamic and respiratory.