Thoracic Epidural and Paravertebral Analgesia

Thoracotomies are among the most painful of surgical incisions. Postoperatively, the movement of the chest with each breath increases the pain, and patients often “splint” to the point of hypercapnea or hypoxia. Substantial analgesia is required to avoid postoperative respiratory complications, but heavy opioid use blunts the respiratory drive and may itself be associated with postoperative complications. Thoracic epidural and paravertebral analgesia can provide this relief, but are sometimes avoided due to anesthesiologists’ concerns about potential difficulty of placement, and the additional dangers of performing an epidural catheter placement in the thoracic region. There are significant differences between the lumbar and thoracic epidural anatomy, and thus the technique also needs to be different. The anatomy of the thoracic spine is considerably different from the lumbar region, the spinal cord lies easily within needle range, and pneumothorax is always a possibility. As seen in Figure 1, the posterior spinous processes of T6-T10 are significantly more angled and thus overlap one another more than in the cervical or epidural region. This overlap and the downward angle require that a midline approach requires a needle placement of at least 45 degrees to the spinal column, as opposed to the nearly 90 degree approach possible in the lumbar region. This angle can be acute enough that the needle actually impacts the underside of the upper spinous process prior to entering the epidural space. As can be appreciated by examining a skeleton, there are articulating surfaces on the underside of the spinous processes that can obstruct the passage of a needle advanced in the midline. As will be demonstrated in the workshop, and can been seen in the Figure 2, a paramedian and/or paravertebral approach is highly beneficial in the thoracic region. For epidural placement, it permits a significantly less angled approach, so that the epidural space will be encountered at a predictable depth in most patients.