Paravertebral Block Versus Simultaneous Ketamine and Lidocaine Infusions for Pain Management in Rib Fracture Patients

Traumatic rib fractures are a common pathology in the trauma population. It is estimated that 10% of all trauma patients have rib fractures. The mainstay of treatment of rib fracture is pain control to allow for good pulmonary hygiene and function. When pain is not controlled, patients have a higher chance of developing pneumonia, which can lead to respiratory failure needing mechanical ventilation, eventually increasing patients' morbidity and mortality. These sequelae are most common in the elderly population. Multiple studies has shown that elderly patients with rib fractures have worse outcomes compared to younger patients with the same fracture pattern.

Pain control for acute rib fracture is achieved using multimodal analgesia to reduce the usage of opioids. Multimodal analgesia means using 2 or more drugs that act by different mechanism to provide pain control. The benefit of multimodal strategy is twofold; decrease the use of opioids and the associated side effects (eg. depressed respiratory drive, delirium, alteration of mental status) and better pain control. However, even with multimodal analgesia, pain control for acute traumatic rib fractures can be challenging. There are currently no validated management guidelines for traumatic rib fracture pain control and the approach varies by organization. At the investigator's institution, the investigators use a scheduled regimen of acetaminophen and NSAIDs, along with opioid medication as needed for pain. If this regimen is insufficient, other adjuncts such as paravertebral blocks (PVBs) and intravenous ketamine and lidocaine infusions are utilized. There are currently limited data on the combined use of ketamine and lidocaine infusions for traumatic rib fractures and it is unclear if the combination is non-inferior to PVBs in this patient population.

Continuous PVB infusion is a well-documented approach for pain control in traumatic rib fractures. But, there are occasionally prohibitive situations that contraindicate PVBs, such as vertebral fractures. Ketamine and lidocaine infusions are an attractive alternative in these situations, but the data regarding efficacy are lacking. Low dose ketamine infusion is a new addition to the pain control algorithm for trauma patients. Given that this is a novel approach, studies evaluating efficacy are sparse. There have been two randomized controlled trials utilizing low dose ketamine in trauma patients and elderly patients with rib fractures. Both were unable to show a decrease in opioid use; however, the authors were able to show a decrease in pain scores in patients with injury severity score (ISS) >15 in both studies. Another study of ketamine infusion in traumatic rib fracture patients admitted to the ICU showed an improvement in numeric pain scores (NPS) and decreased opioids requirements but, as in the previous studies, the ISS of these patients was very high (40) in both the ketamine and non-ketamine groups making generalization to the overall trauma population difficult.

Lidocaine has also been extensively studied as a local anesthetic and more recently has become popular as an infusion for systemic pain control. A recent review article compared 16 randomized control trials of lidocaine infusion on postoperative patients and showed that patients undergoing abdominal surgery had significant decreases in postoperative opioid consumption and improved pain scores. There has been some research into lidocaine infusions in burn patients showing that it can decrease opioid usage by 25%, but the cohort was small and there was no difference in reported pain scores. These data are intriguing but the applicability to trauma patients is questionable. Unfortunately, there has been no study to assess lidocaine infusions in patients with traumatic rib fractures. The investigators believe that there is a role for simultaneous lidocaine and ketamine infusions in traumatic rib fracture patients that may provide better pain control than each one used as a single infusion. The investigators propose a prospective, randomized open label clinical trial evaluating continuous infusion of ropivacaine via PVBs against simultaneous ketamine and lidocaine infusions. The instigators hypothesize that simultaneous lidocaine and ketamine infusions is non inferior to PVBs in traumatic rib fracture patients. The results of this study could help guide pain control strategies in this patient population.