Anesthesia, Pain Control and Sedation
Anesthesia, Pain Control and Sedation
This domain covers local anesthesia, sedation, and general anesthesia as applied to OMFS. You must know the pharmacology of local anesthetics (lidocaine, articaine, bupivacaine), vasoconstrictors (epinephrine), and their maximum doses. Understand the techniques of local anesthesia: infiltration, inferior alveolar nerve block, Gow-Gates, and Vazirani-Akinosi. Also, know the principles of conscious sedation (midazolam, nitrous oxide) and general anesthesia (induction agents, muscle relaxants). Pain control includes analgesics (NSAIDs, opioids) and the WHO analgesic ladder.
Traps: Questions often test the maximum dose of lidocaine with epinephrine (7 mg/kg, not to exceed 500 mg). Another trap is the paresthesia risk with articaine (higher than lidocaine) and the methemoglobinemia risk with prilocaine. Also, know that epinephrine is contraindicated in patients with unstable angina or severe hypertension. For sedation, know the ASA guidelines for fasting (2 hours for clear fluids, 6 hours for light meal).
Rule of thumb: For inferior alveolar nerve block, use a 25-gauge needle, aspirate before injection, and deposit 1.5 mL of solution. For pediatric patients, calculate maximum dose based on weight.
Worked example: A 70-kg patient needs extraction. Maximum dose of 2% lidocaine with 1:100,000 epinephrine: 7 mg/kg × 70 kg = 490 mg. Each 1.8 mL cartridge contains 36 mg lidocaine. Maximum cartridges = 490/36 ≈ 13.6, so do not exceed 13 cartridges.