*Extracted from comprehensive anesthesia notes.*

Preparatory Mindset

Focus on: physiologic effects of anesthesia, drug mechanisms, airway management, and complication recognition. Exam questions often test classification systems (ASA, airway assessment) and complication management.

Core Concepts

1. Overview

• Neuraxial anesthesia includes spinal, epidural, combined spinal-epidural (CSEA), and caudal anesthesia.

• - Landmarks: L4 (supracrustal line), S2, sacral hiatus


• - Ligaments: supraspinous → interspinous → ligamentum flavum


• - Spaces: epidural space; subarachnoid space (contains CSF)


• - Spinal cord ends at L1 in adults, L3 in children

Indications

• - Surgery below T4: lower abdomen, pelvis, perineum, lower extremities, cesarean section

• - Patient refusal, increased ICP, hypovolemia, coagulopathy, local infection, severe valvular stenosis

• - Lateral decubitus (most common), sitting, prone

• - Adults: L2–3, L3–4, L4–5


• - Children: L3–4, L4–5 (below spinal cord)

• - Skin → fat → supraspinous → interspinous → ligamentum flavum → epidural space → dura →


• subarachnoid space (CSF backflow)

• - Short: Lidocaine


• - Long: Bupivacaine (0.5%–0.75%)


• - Duration affected by baricity, position, vasoconstrictors

Indications

• - Abdominal/pelvic surgery, labor analgesia, postoperative pain

• - Same as spinal anesthesia

• - Loss of resistance (to air/saline) when entering epidural space

• - 3–5 mL lidocaine ± epinephrine: rule out intravascular or subarachnoid injection

• - Lidocaine, bupivacaine, ropivacaine


• - Spread: ~1–2 mL per dermatome

• - Rapid, dense block (spinal) + flexible duration (epidural catheter)

• - Injection via sacral hiatus; blocks sacral/coccygeal nerves


• - Used for perineal procedures

• - Space: Subarachnoid (spinal) vs epidural (epidural)


• - Onset: fast (2–5 min) vs slow (15–20 min)


• - Dose: small vs large


• - CSF: yes vs no


• - Hypotension: rapid vs gradual


• - Headache: common (PDPH) vs rare

• - Hypotension (most common): sympathetic block → treat with fluids, Trendelenburg, vasopressors


• - Post-dural puncture headache (PDPH): CSF leak → bed rest, fluids, caffeine, blood patch


• - Urinary retention: bladder catheter


• - Total spinal: respiratory distress, hypotension → intubate, resuscitate


• - Epidural hematoma/abscess: urgent neurologic evaluation


• - Nausea, infection, local anesthetic toxicity

• - Cervical plexus: neck surgery


• - Brachial plexus: shoulder/arm surgery


• - Lumbar/femoral/saphenous: hip, knee, leg surgery


• - Rectus sheath: abdominal wall procedures

High-Yield Points

• ASA classification is a must-know for exam


• Understand differences between general vs regional anesthesia


• Complications and their management are frequently tested


• Know the Mallampati score and airway assessment criteria