Liposomal Bupivacaine in Shoulder Arthroscopy

Background: The research study is being conducted to see if using the liposomal Bupivacaine for the Interscalene block will improve the patient pain control and the whole patient's experience 48 hours after surgery when compared to using the regular Marcaine (bupivacaine hydrochloride) in addition to the dexamethasone. All preoperative, surgical, post-operative care in the recovery room, and discharge instructions will be the same as any other patient undergoing this surgery. Study procedures: 1. After obtaining informed consent, an anesthesiologist will receive an envelope with result of randomization. Patients will receive a single injection interscalene nerve block prior to surgery 2. Patients will be randomized to one of two groups: * GROUP 1 liposomal Bupivacaine - will receive a 20 ml mixture of 10 ml of Liposomal Bupivacaine 1.3% and 10 ml of Bupivacaine HCl 0.5%. * GROUP 2 Bupivacaine with dexamethasone - will receive 20 ml of Bupivacaine HCl 0.5% with 4 mg of preservative-free dexamethasone. 4\. Patients will undergo general endotracheal anesthesia with inhaled anesthetic (Sevoflurane) for a goal MAC 1.0. Other than the aforementioned interscalene nerve block, patients will not receive any other local anesthetic. 5\. Patients will receive a multimodal analgesic and antiemetic regimen standardized for shoulder arthroscopies at our institution. Preoperatively, all patients will receive 300 mg of gabapentin and 1,000 mg of acetaminophen orally. Intraoperatively, patients will receive 4 mg of ondansetron and 15 mg of ketorolac intravenously. Postoperatively, patients will remain on an oral regimen of 300 mg of gabapentin three times daily for one week, and 1,000 mg of acetaminophen and 10 mg of ketorolac every 8 hours for 48 hours after surgery. 6\. Additional intraoperative or postoperative opioid analgesics will be administered as needed. Patients with a history of PONV or otherwise deemed high risk for PONV by the attending anesthesiologist wil