El efecto del bloqueo nervioso con bupivacaína liposomal (Exparel) en la cirugía del manguito rotador

Nerve blocks are typically performed for shoulder surgery for perioperative pain control. This is performed in the shoulder using an interscalene block, which is localized between the anterior and middle scalene muscles in the neck and provides analgesia to the clavicle, shoulder and its capsule and some to the arm. Using this method allows for conscious sedation to be used over general anesthesia, mitigating the dangers associated with the latter, and also comes with the added benefit of providing improved postoperative analgesia.

Bupivacaine is the medication that is typically used for these procedures to provide the analgesia in these sensory patterns. It works by binding to the intracellular portion of voltage-gated sodium channels, preventing depolarization of the nerve and subsequently inhibiting transmission of nerve signals. Typical interscalene blocks have been shown to have pain control for 6-8 hours and have an effect decreasing opioid usage for up to 24 hours. Liposomal bupivacaine, trade name Exparel, was recently introduced as an alternative to drugs such as bupivacaine, but boasting a longer duration of action. In Exparel, bupivacaine is stored in liposomes, which allows for a controlled and longer duration of release of the analgesia-producing molecules. This allows nerve blockades to last longer, allowing for longer prevention of neurotransmitter release. It was initially only approved for local infiltration, most notably in the joint capsule for a total knee arthroplasty. Recently however, it was FDA approved for interscalene blocks, opening up a new avenue for pain control modalities. No studies have yet been performed comparing the difference in analgesia provided by liposomal bupivacaine compared to bupivacaine alone in the context of interscalene blocks in rotator cuff surgery

Nerve blocks with local anesthetics has been proven safe and effective for perioperative pain control. With recent talks of healthcare providers decreasing narcotic usage postoperatively in an effort to prevent opiate addiction, longer acting nerve blocks are becoming more and more appealing. By increasing the duration of a nerve blockade, postoperative narcotic use may be significantly decreased, with minimal risk of harm to the patient.

This is a prospective, double-blinded (surgeon and patient) randomized therapeutic trial. Patients will either receive a standard interscalene block with bupivacaine (25 cc of bupivacaine) or will receive similar dosing of liposomal bupivacaine mixed with bupivacaine (10cc liposomal bupivacaine + 15cc bupivacaine), which has recently been approved and instituted. These blocks (both) are currently in practice at the study institution and the decision of which to use is currently up to the anesthesiologist. It is current practice that every patient undergoing a rotator cuff surgery is offered a nerve block. Data will be prospectively collected and the data from the experimental group will be compared to the control group at the completion of the study period.

Patents will present for surgery and follow up postoperatively as they would routinely for rotator cuff surgery or shoulder arthroscopy. The anesthesiologist administering the injection will be not be blinded to the mixture of injection (the surgeon and the patient will), which will be designated and randomized prior to administration. They will order and draw up the medication as they have been previously with no change in the standard of care.

When discharged home, patients will be asked to keep a log of their narcotic consumption, as well as bringing in their prescription vial to the postoperative follow up and also logging other medications that are consumed during this time period. They will also be asked to log their pain scores in the form of a standardized VAS pain scale form that they will fill out daily until their first follow up visit.