The effect of continuous interscalene brachial plexus block with 0.125% bupivacaine vs 0.2% ropivacaine on pain relief, diaphragmatic motility, and ventilatory function.

Study Objective: Outpatient continuous interscalene brachial plexus blocks containing bupivacaine or ropivacaine are commonly used to control pain after shoulder surgery. Interscalene blocks cause hemidiaphragmatic paresis. Because ropivacaine preferentially blocks sensory fibers, it may cause less blockade of the phrenic nerve.