Hemidiaphragmatic Paralysis With Diluted Continuous Interscalene Plexus Infusions

Interscalene brachial plexus block (ISB) constitutes the analgesic criterion standard for shoulder surgery. However, it is associated with a high incidence of hemidiaphragmatic paralysis (HDP) that may not be tolerated by patients with chronic pulmonary disease. Continuous ISBs have not avoided this complication with the reported and regularly used local anesthetic dilutions (i.e. 0.125% bupivacaine, 0.25% ropivacaine, etc). This observational study will register the incidence of HDP in continuous interscalene block (CISB) using a very diluted solution of levobupivacaine (0.04%) in patients undergoing arthroscopic shoulder surgery. The main objective of this study is to determine the frequency of HDP the first postoperative day before patient discharge(POD).