Understanding Epidural Anesthesia

Epidural anesthesia is a versatile regional anesthesia technique involving catheter placement in the epidural space for continuous analgesia or anesthesia. This comprehensive guide covers essential knowledge for anesthesia residents.

Anatomical Considerations

The epidural space is a potential space between:

• Ligamentum flavum (anterior boundary)
• Dura mater (posterior boundary)
• Extends from foramen magnum to sacrococcygeal membrane
• Contains fat, blood vessels, and nerve roots

Key anatomical landmarks:

• Interspinous spaces (Tuffier's line at L4)
• Posterior superior iliac spines
• Spinous processes

Physiological Effects

1. Sensory Blockade:
   • Dose-dependent dermatomal coverage
   • Progressive loss: Temperature → Pain → Touch → Proprioception
2. Motor Blockade:
   • Concentration-dependent (lower concentrations preserve motor function)
   • Bromage scale assessment
3. Sympathetic Blockade:
   • Vasodilation → decreased systemic vascular resistance
   • Potential hypotension (especially with thoracic epidurals)

Indications

• Obstetrics: Labor analgesia, cesarean delivery
• Postoperative Pain: Thoracic, abdominal, orthopedic surgeries
• Chronic Pain: Cancer pain, radiculopathy
• Surgical Anesthesia: Lower abdominal, pelvic, lower extremity procedures
• Vascular Procedures: Aortic surgery, peripheral vascular reconstructions

Contraindications

Absolute:

• Patient refusal
• Infection at insertion site
• Coagulopathy (INR >1.5, platelets <80,000, therapeutic anticoagulation)
• Increased ICP
• Severe hypovolemia

Relative:

• Spinal deformities
• Pre-existing neurological disorders
• Septicemia
• Uncooperative patient

Pharmacology

Common local anesthetics and dosing:

Agent	Concentration (%)	Onset (min)	Duration (hr)
Bupivacaine	0.0625-0.25	10-20	2-5
Ropivacaine	0.1-0.2	10-15	2-4
Lidocaine	1-2	5-15	1-1.5

Next Steps

Ready to master the technique? See our Step-by-Step Guide to Epidural Catheter Insertion. Learn about essential equipment in our Epidural Needles and Equipment guide.