exparel interscalene vs indwelling catheter

Conditions: Pain

Summary: the investigators are comparing an indwelling catheter with intermediate duration local anesthetic to a single shot peripheral nerve block with long acting a local anesthetic (exparel).

while placing an indwelling nerve catheter can prolong pain control, it can also have drawbacks and complications. while major complications like pneumothorax and hemidiaphragmatic paresis from interscalene continuous peripheral nerve blocks (cpnb) are rare, minor adverse effects associated with cpnbs may be more common. they include infection and anatomical damage to blood vessels and nerves due to the indwelling catheter. in addition, catheters take a significantly longer time to set up and place than single shot blocks, which is important as there is often a rush to block patients and trying to get them into the operating room on time. furthermore, the needle used for catheter placement is larger than the single shot needles, which creates more discomfort to patients during the nerve block. the catheter itself is taped around the entire sides and back of the patient's neck, which is also uncomfortable for patients. because of how shallow the interscalene block is, the catheter is often found to be dislodged from operating room positioning, patient transport or movement, which negates the placement of the catheter. an indwelling catheter must also be followed up by the acute pain service team until the catheter is removed. exparel, or liposomal bupivacaine, is formulated to release low dose bupivacaine over 96 hours, and was recently approved by the fda in april 2018 to be used in interscalene blocks. the sustained release of local anesthetic could theoretically act similarly to the continuous infusion of local anesthetic through an indwelling interscalene catheter, and could thus avoid the need for placement of a catheter. current existing data, although inconclusive, has in some studies shown an equal analgesic effect as catheters. as per pharmacy, the cost of the on-q pump and the local anesthesia needed for the pump together cost $390 for each indwelling catheter placed, not including the cost of anesthesia and pharmacy supplies and labor. the cost of each 20 ml vial of exparel is less at $285 and, for a single shot nerve block, would avoid the extra costs and time needed for a catheter placement. the investigators would like to perform a prospective randomized controlled pilot study to examine the efficacy of single shot interscalene blocks using exparel versus the traditional interscalene catheter used at our institution. the purpose of the study the investigators are proposing is to determine if single shot interscalene nerve blocks using exparel can provide equivalent or better analgesia than indwelling interscalene catheter in patients who undergo total shoulder replacement surgery. if so, single shot interscalene nerve blocks with exparel may serve as a quicker, easier, cheaper, safer, and more comfortable alternative to placing indwelling interscalene catheters.

Eligibility criteria:
inclusion criteria: * american society of anesthesia (asa) 1, 2, and 3 * ages 40-74 * patients scheduled for total shoulder replacement exclusion criteria: * asa 4 and 5 * pre-existing pain disorder * regular consumption of chronic pain medication * pregnant women * any medical condition such as a clotting disorder * anatomic abnormality that precludes use of an indwelling scalene catheter * body mass index (bmi) \>40 * patient refusal * pre-existing diabetic neuropathy or hemoglobin a1c \>9 * failed block

Keywords: shoulder surgery, post operative pain