Trial of Injected Liposomal Bupivacaine vs Bupivacaine Infusion After Surgical Stabilization of Rib Fractures

Rib fractures represent a common injury pattern with high associated morbidity and mortality. Effective pain control in both the acute and long term periods remains a challenge. Surgical stabilization of rib fractures (SSRF) is now a recommended treatment for patients with severe chest wall injuries. In addition to stabilization of the chest wall, SSRF offers a unique opportunity to deliver directed, loco-regional anesthesia. Loco-regional anesthesia is a recognized, essential component of multi-modal anesthesia for patients with rib fractures in order to both decrease pain and minimize the use of opioids and their associated side effects.

Delivery options for loco-regional anesthesia to patients with rib fractures share in common the intention of anesthetizing the intercostal nerves. Moving from the spinal cord laterally, modalities include thoracic epidural catheters, paravertebral blocks or catheters, and rib/intercostal blocks. Although rib blocks may be accomplished via a variety of techniques, the two most common intra-operative techniques are video-assisted thoracoscopic surgery (VATS) intercostal nerve blocks and indwelling, subscapular catheters In general, neuraxial modalities such as thoracic epidural and para-vertebral injections/catheters are subject to a wide array of limitations, including patient coagulopathy (International Normalized Ratio > 1.5), co-existing spine fractures, peri-insertion, peri-removal withholding of venous thromboembolism pharmacoprophylaxis, and provider availability. For these reasons, our current practice is to insert a subscapular "pain catheter" at the conclusion of the SSRF operation; this catheter is able to deliver a continuous infusion of 0.25% bupivacaine and may be left in place for several days.

Although favorable results using the pain catheter have been published in patients with rib fractures who have not undergone SSRF, we have noticed several limitations to this treatment modality. First, position is highly variable; and, because the catheter is not truly in the space of the intercostal nerves, drug delivery is likely irregular. This variability may be particularly relevant in obese patients; and the median body mass index of patient who underwent SSRF at Denver Health is 29 kg/m^2. Beyond catheter placement, we have also experienced issues with leakage of drug from the skin entry site of the catheter. Moreover, catheters frequently become dislodged or inadvertently removed during patient transport. Further, the indwelling foreign body likely introduces some risk of infection. Finally, the presence of the catheter is distressing to many patients.

Liposomal bupivacaine (Exparel, Pacira Pharmaceuticals, Inc., Parsippany, NJ, www.pacira.com) has been shown to provide sustained analgesia for up to 72 hours following a single injection of the drug delivery system. The safety and efficacy of liposomal bupivacaine has been evaluated in over 1,300 subjects and 21 clinical trials. Although many of these trials have included thoracic surgery patients, no trial has evaluated the efficacy and safety of liposomal bupivacaine administered to patients with rib fractures undergoing SSRF. Potential benefits as compared to current practice include directed injection immediately adjacent to the intercostal nerve using a VATS approach, as well as obviation of the need for an indwelling catheter. The hypothesis of the current clinical trial is that, among patients undergoing SSRF, liposomal bupivacaine delivered via video assisted thoracic surgery (VATS) is an intercostal nerve block that provides comparable analgesia to the pain catheter, as measured by pulmonary function, numeric pain scoring, and postoperative narcotic use.