Epidural Anesthesia

Background

Epidural anesthesia is used for analgesia in operations in the abdomen, perineum and extremities as well as being used for postoperative pain control. Epidural anesthesia used during the course of general anesthesia and recovery has been found to reduce postoperative complications compared with the use of intravenous opioids alone for analgesia.

Epidural analgesia shows a greater preservation of preoperative pulmonary function, decreases myocardial ischemia, decreases the incidence of thromboembolic events and hastens the recovery of bowel function when compared with intravenous opio-ids. Epidural analgesia also increases blood flow to the viscera seen in lower anasto-motic leak rates for procedures using a combination of general and epidural anesthesia.

Procedure

Highly lipophillic opioids such as fentanyl are combined with local anesthetics such as bupivicaine in continuous infusions to provide optimal analgesia with the least side effects. The epidural space extends from the foramen magnum to the sac-rococcygeal membrane, and local anesthetics can be deposited in this space to block neural transmission diffusing intrathecally to block nerve roots. After catheter placement subarachnoid or intravenous cannulation is ruled out by injecting a test dose and monitoring for spinal anesthesia or tachycardia. The dose of anesthetic varies according to the level of anesthesia desired. Complications include arterial hypotension, transient backache, dural puncture, total spinal anesthesia, and epidural hematoma. Contraindications to epidural anesthesia include major coagulation defects, uncorrected hypovolemia, infection at the needle insertion site and patients with unstable neurologic disease.

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