Regional analgesia in thoracic trauma

Abstract

The contemporary multimodal therapeutic approach to the management of thoracic trauma is intended to decrease patient morbidity and mortality, improve functional recovery and long-term quality of life after trauma. It includes early diagnosis and treatment of injuries, the utilization of minimally invasive surgical techniques (e.g. thoracoscopic surgery, endovascular repair of thoracic aortic injuries), modern lung supportive therapies, physiotherapy, early nutrition and ambulation, and early and adequate pain control. The conceptual shift in the post-traumatic pain management is the result of a better understanding of the role of pain in stimulating the catabolic stress response after trauma with resultant tachycardia, increased oxygen consumption, hypercoagulability, and immunosupresssion. The stress response after trauma is even greater than the stress response after elective surgery. It is paramount therefore to initiate a strategy of pain control early (at the point of injury preferably) and continue it throughout the entire hospital stay (in ITU and after that) aiming to decrease the peripheral sensitisation from the injury and the central sensitisation with its subsequent windup. This concept has been called preventive analgesia and it is best achieved by capitalizing on the synergistic analgesia offered by various pharmacological agents and regional techniques (multimodal analgesia). The experience with multimodal preventive analgesia arises mainly from studies in postoperative patients; however, new data is emerging from the progress that military medical care has made in managing multiple trauma critically ill-wounded soldiers. Regional anaesthesia-analgesia may play an important role as part of the multimodal analgesia in thoracic trauma patients. It has been shown repeatedly in postoperative studies to offer improved analgesia, superior patient outcomes and better patient satisfaction. Numerous studies report improved analgesia after continuous neuraxial and peripheral regional blocks compared to systemic opioids, and less side effects such as nausea and vomiting, excessive sedation, respiratory depression, urinary retention, postoperative ileus and pruritus. Several patient outcomes such as the duration of ITU-stay, overall hospital-stay, postoperative morbidity (cardiac, pulmonary, ileus, infective complications) and mortality also show improvement with perioperative continuous regional anaesthesia. There is also strong evidence that regional anaesthesia improves patient satisfaction when compared to systemic analgesia. Other long-term patient outcomes such as the prevalence of posttraumatic stress disorders and chronic pain may be also improved, although it remains unclear whether better analgesia or the choice of analgesic technique is responsible for the beneficial effects. The advantages of epidural analgesia (regardless of the epidural delivery technique i.e. continuous infusion or patient-controlled) when compared to intravenous systemic analgesia have been well demonstrated in post-thoracotomy patients - the most commonly studied model of thoracic “trauma”. Paravertebral analgesia, confirmed to be equally analgesic-effective with thoracic epidural with fewer side effects, and superior to parenteral opioids, may be used in selective cases. There is generally a paucity of prospective randomised controlled studies to evaluate regional versus systemic analgesia in “true” thoracic trauma patients. Several retrospective studies have demonstrated better analgesia with thoracic epidural than intravenous patient-controlled analgesia, and shorter ITU stay in chest trauma patients with multiple rib fracture. In a recent randomised controlled study, continuous thoracic paravertebral analgesia proved to be as effective as continuous thoracic epidural for the pain management in patients with unilateral multiple rib fractures, and they were both associated with similar improvement in pulmonary function. The potential risks associated with the use of local anaesthetics (toxicity from inadvertent intravascular injection or overdose) can be avoided by using less toxic local anaesthetics as a sole agent or in association with adjunctive analgesics (drugs that enhance the analgesic effect of the primary pain relieving drug, often in a synergistic way, and allow a reduction of the local anaesthetic dose to levels that decrease the risk of toxicity). A scrupulous technique and the immediate availability of the resuscitation equipment and drugs (intralipid) are paramount. A meticulous technique also minimizes some other risks of regional blockade such as nerve injury, pneumothorax, inadvertent epidural or subarachnoid spread, hematoma, and infection. In conclusion, ongoing improvements in pain management after thoracic trauma include aggressive pain control from the initial point of evacuation and throughout the continuum of care in ITU and hospital wards. There is strong recognition that adequate pain management improves patient outcomes. Whether a specific drug, technique or combination is responsible is less clear, although some techniques are associated with better analgesia and less side effects than other. A multimodal approach is the best, and regional anaesthesia, where suitable, must be considered early in the management of pain control in thoracic trauma patients.