Emergency Medicine — USMLE Step 3 Practice
Emergency medicine on USMLE Step 3 covers the initial evaluation and stabilization of critically ill and injured patients. Topics include trauma, toxicology, environmental emergencies, and resuscitation protocols.
Frequently Asked Questions
What is the ATLS primary survey sequence on USMLE Step 3?
ABCDE: Airway (with cervical spine protection) → Breathing (ventilation) → Circulation (hemorrhage control) → Disability (neuro, GCS, pupils) → Exposure (fully undress patient, prevent hypothermia). Identify and treat life threats at each step before moving to the next. Simultaneous with IV access, monitoring, and labs.
What are the toxidromes tested most on Step 3?
Cholinergic (SLUDGE/DUMBELS): salivation, lacrimation, urination, defecation, GI distress, emesis; atropine + pralidoxime. Anticholinergic: hot/dry/red/mad/blind; physostigmine for severe. Sympathomimetic: HTN, tachycardia, hyperthermia, mydriasis; benzodiazepines. Opioid: miosis, respiratory depression, altered consciousness; naloxone. Serotonin syndrome: hyperthermia, clonus, diaphoresis; cyproheptadine.
How do you manage anaphylaxis on USMLE Step 3?
IM epinephrine 0.3-0.5 mg into the anterolateral thigh is the first and most important treatment. Lay patient flat, elevate legs. Supplemental O2, IV fluids for hypotension. Antihistamines (diphenhydramine + ranitidine) and corticosteroids are adjuncts, not primary treatment. Observe for biphasic reaction (4-8 hours). Discharge with epinephrine autoinjector prescription.
What is the management of heat stroke on Step 3?
Classic heat stroke: elderly during heat wave, anhidrotic. Exertional heat stroke: young athletes, diaphoretic. Both: core temp >40°C with CNS dysfunction. Treatment: rapid cooling is critical — evaporative cooling (mist + fan) or ice water immersion. Target temp <39°C within 30 minutes. Avoid antipyretics (no benefit; organ damage is not from pyrogenic mechanism).
How do you manage a patient with suspected carbon monoxide poisoning?
CO poisoning: cherry-red skin (unreliable), headache, confusion, nausea in multiple people from same location. Pulse oximetry is FALSELY NORMAL (cannot distinguish CO-Hgb from O2-Hgb). Diagnose with co-oximetry (COHgb level). Treatment: 100% O2 via non-rebreather mask. Hyperbaric oxygen for COHgb >25%, pregnancy, neurological symptoms, or cardiac involvement.
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