Liposomal Bupivacaine Single-Injection Interscalene Block vs. Continuous Interscalene Block for Primary Total Shoulder Arthroplasty

Inclusion criteria

• Adult patients with an American Society of Anesthesiologists (ASA) physiological status I-III
• Patients presenting for unilateral primary total shoulder arthroplasty (includes anatomic and reverse total shoulder arthroplasty).
• Patients 18 years of age and older
• Able to provide informed consent for him or herself

Exclusion criteria

• Chronic pain syndromes
• Chronic opioid use (>1 month) with OME >5 mg/day OR acute opioid use (< 1 month) with OME > 30 mg/day.
• Body mass index (BMI) > 45 kg/m2
• Severe drug allergy* to medications used in this study, including non-steroidal anti-inflammatory drugs (i.e. celecoxib) and local anesthetics. *defined as an immune reaction resulting in shortness of breath, hives, anaphylaxis, wheezing, and fever
• Personal or family history of malignant hyperthermia.
• Major systemic medical problems such as:

• Pre-existing severe renal disorder defined as glomerular filtration rate (GFR) <50 units/m2 (if labs are available), currently on dialysis, or highly suspected based on history.
• Severe hepatic disorder defined as current or past diagnosis of acute/subacute necrosis of liver, acute hepatic failure, chronic liver disease, cirrhosis (primary biliary cirrhosis), chronic hepatitis/toxic hepatitis, liver abscess, hepatic coma, hepatorenal syndrome, other disorders of liver
• Pre-existing medical history of moderate to severe pulmonary disease requiring medical therapy (obstructive and/or restrictive), use of home oxygen, preoperative baseline oxygen saturation < 93% on room air.
• History of contralateral hemidiaphragm dysfunction (e.g., paralysis) or phrenic nerve injury.
• Contraindication to a regional anesthesia technique (e.g., preexisting neuropathy+ in the operative extremity, coagulopathy, sepsis, infection at site of injection, uncooperative, and refusal).

o + pre-existing neuropathy includes sensory and/or motor deficits due to nerve insult of surgical extremity, radicular symptoms of surgical extremity, history of unresolved brachial plexus injury/brachial plexopathy, and tumors of the brachial plexus. Patients with nerve compression distal to site of surgery, such as history of carpal tunnel syndrome or cubital tunnel syndrome, are NOT considered contraindications to regional anesthesia.

• Known to be currently pregnant or actively breastfeeding++

o ++ All surgical patients are currently screened using a standardized Pregnancy Assessment tool (http://mayoweb.mayo.edu/sp-forms/mc8800-mc8899/mc8801-161.pdf)

• Impaired cognition (e.g. Alzheimer's disease, moderate to severe dementia, encephalopathy)
• Non-English speaking