Clinical Research Directory

Inclusion Criteria: 1. Adults aged 18 to 80 years 2. ASA physical status 1-3 3. Undergoing primary shoulder surgery with interscalene nerve block Exclusion Criteria: 1. ASA 4 or 5 2. Revision shoulder surgery 3. Daily chronic opioid use (over 3 months of continuous opioid use) 4. Inability to communicate pain scores or need for analgesia 5. Infection at the site of block placement 6. Age under 18 years old or greater than 80 years old 7. Pregnant women (as determined by point-of-care serum bHCG) 8. Intolerance/allergy to local anesthetics 9. Weight \<50 kg 10. BMI \> 40 11. severe pulmonary disease including chronic obstructive pulmonary disease and restrictive lung disease 12. Suspected, or known addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past 2 years. 13. Uncontrolled anxiety, schizophrenia, or other psychiatric disorder that, in the opinion of the investigator, may interfere with study assessments or compliance. 14. 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.