Epidural Anaesthesia
Epidural anaesthesia involves injection of local anaesthetic into the epidural space (potential space between ligamentum flavum and dura) producing segmental sensory block with less motor block than spinal. Anatomy:...
Clinical board
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Urgent signals
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- Total spinal from accidental dural puncture
- Severe hypotension with cardiovascular collapse
- Toxicity from intravascular local anaesthetic injection
- Epidural haematoma with neurological deficits
Exam focus
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- ANZCA Final Written
- ANZCA Final Clinical Viva
- ANZCA Final Medical Viva
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Quick Answer
Epidural anaesthesia involves injection of local anaesthetic into the epidural space (potential space between ligamentum flavum and dura) producing segmental sensory block with less motor block than spinal. Anatomy: Epidural space extends from foramen magnum to sacral hiatus (sacral canal), bounded anteriorly by posterior longitudinal ligament, posteriorly by ligamentum flavum, laterally by pedicles and intervertebral foramina. Technique: Loss of resistance (saline or air) or hanging drop method to identify epidural space, catheter inserted 3-5 cm into space. Labour analgesia: 0.0625-0.1% bupivacaine with fentanyl 2-5 μg/mL infused at 8-12 mL/hour or PCEA. Caesarean section: 15-20 mL 2% lidocaine or 0.5% bupivacaine with adrenaline (1:200,000) to prolong block and reduce toxicity. Contraindications: Patient refusal, coagulopathy (platelets <80-100 × 10⁹/L), infection at site, severe hypovolaemia. Complications: Accidental dural puncture (1-2%, PDPH 50-70%), intravascular injection (toxicity), hypotension (sympathetic blockade), inadequate block (10-15%, may need conversion to general). Advantages over spinal: Slower onset (15-30 min), can extend block duration via catheter, less hypotension, segmental block can be controlled. Indigenous patients may have higher rates of obesity making epidural technically challenging; ultrasound guidance and culturally sensitive positioning assistance are recommended. [1-10]