Spinal analgesia

Abstract

The use of spinal (epidural or intrathecal) narcotics and local anesthetics for postoperative analgesia is becoming popular. The pharmacokinetics and pharmacodynamics of spinal narcotics are very important to determine dosage and intervals with bolus administration. Less lipid-soluble narcotics have slower onset, greater dermatomal spread, and longer duration of action than more lipid-soluble narcotics. Certain specific narcotics have unusual features affecting their use. Bupivacaine is the local anesthetic of choice for epidural analgesia, but lidocaine and others have been used successfully. Both bolus and infusion technique can be used for a given practice. Epidural rather than intrathecal techniques are needed to provide analgesia consistently for more than 24 hours. Many surgical cases are appropriate for spinal analgesia; both analgesia and other benefits (for example, sympathetic block, improved pulmonary function) need to be considered. Spinal analgesia for intensive-care critically ill patients can be very beneficial but requires extensive follow-up. Both narcotics and local anesthetics by spinal application have been shown to be an improvement over most 'standard orders' for analgesia, pulmonary function, and hospital stay; other possible benefits are less certain or specific to technique and surgery. Possible complications are extensive and require consistent physician monitoring of patient response.