Comparative study for the postoperative analgesic efficacy of 20 mL at 0.5, 0.75, and 1% ropivacaine in posterior brachial plexus block.

Background And Objectives: Arthroscopic shoulder surgeries are associated with severe postoperative pain. Among the analgesic techniques available, brachial plexus block has the best results. The objective of this study was to determine which concentration of local analgesic used in the posterior brachial plexus block provides longer postoperative analgesia.

Methods: Ninety patients undergoing posterior brachial plexus block were randomly divided into three groups of 30 patients each. Group 1: 20 mL of 0.5% ropivacaine; Group 2: 20 mL of 0.75% ropivacaine; and Group 3: 20 mL of 1% ropivacaine. The blockade was evaluated by assessing the thermal sensitivity using a cotton pad with alcohol and postoperative pain was evaluated according to a Verbal Numeric Scale (VNS) in the first 48 hours.

Results: Postoperative analgesia was similar in all three groups according to the parameters evaluated: mean VNS, time until the first complaint of pain, and postoperative opioid consumption.

Conclusions: This study demonstrated that posterior brachial plexus block provides effective analgesia for shoulder surgeries. Twenty milliliters of ropivacaine in the different concentrations used in this study promoted similar analgesia.