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 American Society of Anesthesiologists (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 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.

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.

Inclusion Criteria:

• English speaking 18-80 year old ASA 1-3 patients
• Primary shoulder surgery
• Must live within a 25 mile radius

Exclusion Criteria:

• ASA 4 or 5
• Revision shoulder surgery
• Diagnosis of chronic pain
• Daily chronic opioid use (over 3 months of continuous opioid use)
• Inability to communicate pain scores or need for analgesia
• Infection at the site of block placement
• Age under 18 years old or greater than 80 years old
• Pregnant women (as determined by point-of-care serum bHCG)
• Intolerance/allergy to local anesthetics
• Weight <50 kg
• BMI > 40
• severe pulmonary disease including chronic obstructive pulmonary disease and restrictive lung disease
• Suspected, or known addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past 2 years.
• Uncontrolled anxiety, schizophrenia, or other psychiatric disorder that, in the opinion of the investigator, may interfere with study assessments or compliance.
• Current or historical evidence of any clinically significant disease or condition that, in the opinion of the investigator, may increase the risk of surgery or complicate the subject's postoperative course.

Patients ages 18-80 undergoing shoulder surgery per standard of care.

Individual participant data will not be shared; patients will be deidentified and no personal information or medical records used once patient has completed the study.