Evaluating Hemidiaphragmatic Paralysis With Prolonged Neural Blockade From an Interscalene Brachial Plexus Block

This prospective observational study aims to evaluate the incidence of hemidiaphragmatic paralysis in patients receiving interscalene brachial plexus nerve block with prolonged neural blockade. English speaking ASA 1-3 patients ages 18-80 receiving prolonged interscalene nerve block will be randomized into 3 groups first group receiving a perineural catheter infusing 0.2% ropivacaine; the second group receiving a single shot injection of 10mL liposomal bupivacaine (Exparel; n=20) plus 5 mL 0.5% bupivacaine and the third group receiving 20mL liposomal bupivacaine plus 5mL bupivacaine (to be determined by the attending anesthesiologist). Primary outcome will be incidence of hemidiaphragmatic paralysis postoperative day 1 as measured by point of care (POCUS) ultrasound. Secondary outcomes include incidence of hemidiaphragmatic paralysis as measured by point of care ultrasound (POCUS) in the immediate postoperative period, postoperative day (POD) 1, POD2, and POD3 and noninvasive measures of pulmonary gas exchange at pre-op, post-op, POD1, POD2, and POD3. Additionally, the investigators will look at pain scores (scale of 0-10) and opioid consumption (in oral morphine equivalents) at previously defined time points listed above. Furthermore, the investigators will record known side effects of interscalene blocks including hoarseness and Horner's syndrome.