Epidural Anesthesia

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Epidural Anesthesia - Spine's Comfort Zone

  • Local anesthetic (LA) injected into epidural space (potential space between dura mater & ligamentum flavum).
  • Advantages: Segmental block, prolonged analgesia (via catheter), ↓ risk of post-dural puncture headache.
  • Disadvantages: Slower onset than spinal, larger LA volume needed, risk of intravascular/subarachnoid injection.
  • Epidural Space Contents: Fat, lymphatics, Batson's venous plexus, nerve roots.
  • Layers Pierced (midline): Skin → Subcutaneous tissue → Supraspinous ligament → Interspinous ligament → Ligamentum flavum → Epidural space. 📌 SSSILE. Neuraxial Anatomy and Epidural Needle Insertion

⭐ A test dose (e.g., 3ml lignocaine with adrenaline 1:200,000) helps detect accidental intravascular or intrathecal placement before injecting the full dose.

Epidural Anesthesia - Green & Red Lights

  • Green Lights (Indications):
    • Surgical: Lower abdominal, pelvic, lower limb surgeries.
    • Obstetrics: Labor analgesia (gold standard), C-section.
    • Pain Management: Post-operative, chronic pain (e.g., cancer).
  • Red Lights (Contraindications):
    • Absolute: Patient refusal, site infection, ↑ICP, severe hypovolemia, coagulopathy (INR > 1.5, Plt < 80k), severe valvular stenosis (AS/MS).
    • Relative: Sepsis, uncooperative, neurological deficit, prior local spine surgery.

⭐ Epidural analgesia is the gold standard for labor pain relief.

Epidural Anesthesia - Epidural Elixirs

  • Local Anesthetics (LAs):
    • Bupivacaine (0.0625%-0.5%), Ropivacaine (0.1%-0.5%), Lidocaine (1%-2%).
    • Mech: Na+ channel block.
  • Opioids:
    • Fentanyl (1-2 µg/mL), Morphine (preservative-free).
    • Mech: Spinal opioid receptors; ↑ analgesia, ↓ LA dose.
  • Adjuvants:
    • Epinephrine (1:200,000): Vasoconstriction → ↑ LA duration, ↓ absorption.
    • Clonidine (α2-agonist): ↑ Analgesia, ↑ block duration.
  • Factors Influencing Effect:
    • Drug: dose, volume, concentration.
    • Injection site, patient position.
    • Pregnancy: ↑ spread (engorged veins).

⭐ Highly lipid-soluble opioids (e.g., Fentanyl) offer faster onset & shorter duration epidurally vs. less lipid-soluble ones (e.g., Morphine).

Epidural Anesthesia - Needle Know-How

  • Needles:
    • Tuohy: 16-18G, curved Huber tip (directs catheter).
    • Crawford: Straight tip (↑ dural puncture risk).
  • Position: Sitting/Lateral decubitus. Tuffier's line (L4-L5).
  • Technique: Loss Of Resistance (LOR) to saline (preferred) or air.
    • 📌 Layers (midline): Skin → SubQ → Supraspinous lig. → Interspinous lig. → Ligamentum flavum → Epidural space.
  • Catheter: Advance 3-5 cm into epidural space.

⭐ Skin-to-epidural depth (adults): 4-6 cm.

Epidural Anesthesia Procedure and Anatomy

Epidural Anesthesia - Trouble Tidings

  • Hypotension: Most common; sympathetic blockade. Manage: Fluids, vasopressors (e.g., phenylephrine, ephedrine).
  • High/Total Spinal: Accidental intrathecal injection. Apnea, profound ↓BP, unconsciousness. Manage: Airway (intubate), ventilate, CPR if needed.
  • PDPH (Post-Dural Puncture Headache): CSF leak. Postural headache. Manage: Conservative (hydration, caffeine, analgesics), epidural blood patch if severe.
  • Epidural Hematoma: Rare, serious. Risk factors: coagulopathy, traumatic tap. New/progressive motor/sensory deficit, back pain, sphincter dysfunction. Urgent MRI, surgical decompression.
  • Epidural Abscess: Rare. Fever, severe back pain, neurological deficits. Risk: Immunocompromised, diabetes. Urgent MRI, antibiotics, possible drainage.
  • Nerve Injury: Direct needle/catheter trauma, hematoma, neurotoxicity. Persistent paresthesia or motor deficit.
  • LAST (Local Anesthetic Systemic Toxicity): CNS excitation (seizures) then depression; CVS toxicity (arrhythmias, cardiac arrest). Manage: Airway, 20% lipid emulsion.

⭐ Epidural hematoma requires urgent surgical decompression, ideally within 8 hours of symptom onset, for best neurological outcome.

High‑Yield Points - ⚡ Biggest Takeaways

  • Epidural space is a potential space; target for analgesia/anesthesia.
  • Tuohy needle (curved tip) used; Loss of Resistance (LOR) technique (air/saline) identifies space.
  • Key indications: labor analgesia, postoperative pain relief.
  • Test dose (e.g., lignocaine + adrenaline) vital for detecting intravascular/intrathecal injection.
  • Risks: PDPH, epidural hematoma/abscess, hypotension, total spinal anesthesia.
  • Achieves segmental blockade, allowing targeted analgesia.
  • Differential blockade: sympathetic (first) > sensory > motor (last).

Practice Questions: Epidural Anesthesia

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Best site for administering spinal anesthesia is the intervertebral space between.

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Flashcards: Epidural Anesthesia

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_____ needle is used in epidural anesthesia and has a blunt curved tip (Huber tip), which helps prevent accidental dural rupture

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_____ needle is used in epidural anesthesia and has a blunt curved tip (Huber tip), which helps prevent accidental dural rupture

Tuohy

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