Epidural Anesthesia and Analgesia
Clinical indications for epidural anesthesia and analgesia have expanded significantly over the past several decades.* Epidural analgesia is often used to supplement general anesthesia (GA) for surgical procedures in patients of all ages with moderate-to-severe comorbid disease; provide analgesia in the intraoperative, postoperative, peripartum, and end-of-life settings; and can be used as the primary anesthetic for surgeries from the mediastinum to the lower extremities. In addition, epidural techniques are used increasingly for diagnostic procedures, acute pain therapy, and management of chronic pain. Epidural blockade may also reduce the surgical stress response, the risk of cancer recurrence, the incidence of perioperative thromboembolic events, and, possibly, the morbidity and mortality associated with major surgery.
This chapter covers the essentials of epidural anesthesia and analgesia. After a brief history of the transformation from single-shot to continuous epidural catheter techniques, it reviews (1) indications for and contraindications to epidural blockade; (2) basic anatomic considerations for epidural placement; (3) physiologic effects of epidural blockade; (4) pharmacology of drugs used for epidural anesthesia and analgesia; (5) techniques for successful epidural placement; and (6) major and minor complications associated with epidural blockade. This chapter also addresses several areas of controversy concerning epidural techniques. These include controversies about epidural space anatomy, the traditional epinephrine test dose, methods used to identify the epidural space, and whether particular clinical outcomes may be improved with epidural techniques when compared to GA. More detailed information about local anesthetics (LAs), the mechanism of neuraxial blockade, the combined spinal-epidural (CSE) technique, obstetric anesthesia, and complications of central neuraxial blockade is provided elsewhere in this textbook.
The neurologist J. Leonard Corning proposed injecting an anesthetic solution into the epidural space in the 1880s, but devoted his research primarily to subarachnoid blocks. Despite coining the term spinal anesthesia, he may unknowingly have been investigating the epidural space. The French physicians Jean Sicard and Fernand Cathelin are credited with the first intentional administration of epidural anesthesia. At the turn of the 20th century, they independently introduced single-shot caudal blocks with cocaine for neurologic and genitourinary procedures, respectively.1 Nineteen years later, the Spanish surgeon Fidel Pagés Miravé described a single-shot thoracolumbar approach to “peridural” anesthesia, identifying the epidural space through subtle tactile distinctions in the ligaments.2 Within a decade and seemingly without the knowledge of Pagés’s work, the Italian surgeon Achille Dogliotti popularized a reproducible loss-of-resistance (LOR) technique to identify the epidural space.3 Contemporaneously, the Argentine surgeon Alberto Gutiérrez described the “sign of the drop” for identification of the epidural space.
A number of innovations by Eugene Aburel, Robert Hingson, Waldo Edwards, and James Southworth, among others, attempted to prolong the single-shot epidural technique. ...