Chapter SPINAL, EPIDURAL, AND 17 CAUDAL ANESTHESIA Alan J.R. Macfarlane, Richard Brull, and Vincent W.S. Chan PRINCIPLES COMBINED SPINAL-EPIDURAL ANESTHESIA PRACTICE Technique ANATOMY CAUDAL ANESTHESIA Spinal Nerves Pharmacology Blood Supply Technique Anatomic Variations COMPLICATIONS MECHANISM OF ACTION Neurologic Drug Uptake and Distribution Cardiovascular Drug Elimination Respiratory PHYSIOLOGIC EFFECTS Infection Cardiovascular Backache Central Nervous System Nausea and Vomiting Respiratory Urinary Retention Gastrointestinal Pruritus Renal Shivering Complications Unique to Epidural Anesthesia INDICATIONS Neuraxial Anesthesia RECENT ADVANCES IN ULTRASONOGRAPHY Neuraxial Analgesia QUESTIONS OF THE DAY CONTRAINDICATIONS Absolute Relative PRINCIPLES SPINAL ANESTHESIA Factors Affecting Block Height Spinal, epidural, and caudal blocks are collectively referred Duration of the Block to as central neuraxial blocks. Significant technical, physi- Pharmacology ologic, and pharmacologic differences exist between the Technique techniques, although all result in one or a combination of Monitoring of the Block sympathetic, sensory, and motor blockade. Spinal anes- EPIDURAL ANESTHESIA thesia requires a small amount of drug to produce rapid, Factors Affecting Epidural Block Height profound, reproducible, but finite sensory analgesia. In Pharmacology contrast, epidural anesthesia progresses more slowly, is Technique commonly prolonged using a catheter, and requires a large amount of local anesthetic, which may be associated with The editors and publisher would like to thank Drs. Kenneth Dras- ner and Merlin D. Larson for contributing to this chapter in the previous edition of this work. It has served as the foundation for the current chapter. 273 Downloaded for Wendy Nguyen (
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