Local Anesthesia, Sedation and Pain Control
This domain tests safe pain control: nerve anatomy, drug dose, patient selection, monitoring and rescue.
Core rules
- Maxillary anesthesia includes posterior superior alveolar, infraorbital, greater palatine and nasopalatine blocks. Mandibular anesthesia includes inferior alveolar nerve block, lingual and buccal infiltration; alternatives are Gow-Gates and Vazirani-Akinosi.
- For inferior alveolar block, target the pterygomandibular space with the mouth wide; aspirate in two planes.
- Calculate maximum dose by weight and concentration. Lidocaine 2% = 20 mg/mL; a 1.8 mL cartridge contains 36 mg. With epinephrine 1:100,000, limit 7 mg/kg; without epinephrine, 4.4 mg/kg. Articaine 4% = 40 mg/mL; a 1.8 mL cartridge contains 72 mg.
- Epinephrine 1:100,000 = 10 micrograms/mL; 1:200,000 = 5 micrograms/mL. Avoid in uncontrolled hyperthyroidism, pheochromocytoma and severe cardiovascular disease; caution with tricyclics and cocaine.
- Sedation ranges from minimal to moderate to deep. Moderate sedation requires monitoring, oxygen, suction, rescue drugs and trained staff. Capnography improves safety.
- Local anesthetic systemic toxicity: stop injection, call help, airway, 100% oxygen, benzodiazepine for seizures, lipid emulsion for severe cardiovascular collapse.
Worked example
A 70 kg adult needs 2% lidocaine with 1:100,000 epinephrine. Maximum 7 mg/kg = 490 mg, capped at 500 mg. Each 1.8 mL cartridge contains 36 mg, so 13.6 cartridges is the calculated limit; clinically use the minimum. If 4% articaine were used, 40 mg/mL, 1.8 mL = 72 mg.
Traps
Using adult mg/kg for a child; injecting into a vessel; not aspirating; sedating without fasting assessment; lacking flumazenil or naloxone.