Eficácia analgésica pós-operatória de diferentes volumes e massas de ropivacaína no bloqueio de plexo braquial pela via posterior

background and objectives: the efficacy of posterior brachial plexus block for shoulder surgeries is demonstrated by different authors. however, there is no consensus on the ideal mass and volume of local anesthetic to be employed. the objetive of this study was to compare different volumes and masses of ropivacaine in posterior brachial plexus block in arthroscopic surgeries of the shoulder. method: sixty patients > 18 years, physical status asa i and ii, scheduled for unilateral arthroscopic surgeries of the shoulder were randomly placed in three groups: a (10 ml to 0.5%), b (20 ml to 0.5%), c (5 ml to 1%). the block was performed with a 22g needle of 100 mm connected to neurostimulator, in a point 3 cm lateral to the midpoint of c6 and c7 interspace, being injected the solution corresponding to each group. the postoperative pain was evaluated at the recovery room and within the first 24 hours of the postoperative period. the groups were compared on length of time until the first complaint of pain, visual numeric scale (vns) score and morphine consumption within the first 24 hours. results: there was no statistically significant difference between the three groups related to age, weight and height. there was no difference in length of time until the first complaint of pain, vns scores over three and morphine consumption in the postoperative period between the groups. conclusions: this study concluded that 5 ml of 1% ropivacaine promoted analgesic efficacy similar to 10 ml or 20 ml of 0.5% ropivacaine in the posterior brachial plexus block using neurostimulator