ABEM Toxicology, Environmental & Infectious Diseases 5 — Questions and Answers
Question 1: A patient on warfarin presents with an INR of 9.8 and active intracranial hemorrhage. Which is the FASTEST and most appropriate reversal strategy?
- Vitamin K 10 mg IV alone
- Fresh frozen plasma 4 units
- 4-factor prothrombin complex concentrate (4F-PCC) (Correct answer)
- Recombinant factor VIIa
Correct answer: 4-factor prothrombin complex concentrate (4F-PCC)
4-factor PCC reverses warfarin-related INR within minutes, contains all vitamin K-dependent factors, requires small volume, and is superior to FFP for emergent reversal.
Question 2: A patient presents with fever, hepatosplenomegaly, and pancytopenia after returning from a tropical trip; a bone marrow biopsy shows macrophages engulfing red blood cells and platelets. What is the diagnosis?
- Disseminated histoplasmosis
- Visceral leishmaniasis (kala-azar) (Correct answer)
- Hemophagocytic lymphohistiocytosis
- Malignant tertian malaria
Correct answer: Visceral leishmaniasis (kala-azar)
Visceral leishmaniasis (kala-azar) causes macrophage invasion of the reticuloendothelial system, presenting with fever, massive splenomegaly, and pancytopenia in a returning traveler.
Question 3: Which ECG finding in a patient with digoxin toxicity is MOST specific for toxicity rather than therapeutic effect?
- PR prolongation
- Bidirectional ventricular tachycardia (Correct answer)
- Scooped ST depression
- QT shortening
Correct answer: Bidirectional ventricular tachycardia
Bidirectional ventricular tachycardia is highly specific for digoxin (and aconitine) toxicity and is not a therapeutic ECG change.
Question 4: A patient presents with fever, cough, and bilateral hilar lymphadenopathy after disturbing bat guano in an Ohio cave. Bronchoalveolar lavage reveals intracellular yeast within macrophages. What is the treatment for severe pulmonary disease?
- Fluconazole 400 mg daily PO
- Itraconazole 200 mg TID for 3 days then BID
- Amphotericin B lipid complex (Correct answer)
- Voriconazole IV loading dose
Correct answer: Amphotericin B lipid complex
Severe or disseminated histoplasmosis requires amphotericin B lipid formulation as initial therapy, followed by step-down to itraconazole after clinical improvement.
Question 5: A construction worker collapses on a hot summer day with core temperature of 41.5°C, anhidrosis, and delirium. What is the MOST effective cooling method to reduce core temperature rapidly?
- Misting fans and evaporative cooling
- Ice water immersion (Correct answer)
- Ice packs to axillae, groin, and neck
- Cooling blanket set at 20°C
Correct answer: Ice water immersion
Ice water immersion provides the fastest rate of core cooling (0.2°C/min) for exertional heat stroke and is the gold standard cooling method.
Question 6: A patient presents with ascending flaccid paralysis, areflexia, and respiratory insufficiency 10 days after a gastroenteritis illness. CSF shows elevated protein with normal glucose and no pleocytosis. What is the most appropriate emergency intervention?
- High-dose methylprednisolone IV
- Plasmapheresis or IVIG
- Intubation and mechanical ventilation if FVC < 20 mL/kg (Correct answer)
- Thiamine 100 mg IV and glucose
Correct answer: Intubation and mechanical ventilation if FVC < 20 mL/kg
In Guillain-Barré syndrome, the most critical emergency intervention is airway management; intubation is indicated when FVC falls below 20 mL/kg or the patient cannot complete a sentence.
Question 7: A patient presents with septic shock from suspected gram-negative bacteremia. Which of the following represents the BEST evidence-based initial fluid resuscitation target in the first 3 hours per surviving sepsis guidelines?
- 30 mL/kg of crystalloid IV, then reassess (Correct answer)
- 1 L boluses until MAP > 65 mmHg, maximum 4 L
- Colloid 20 mL/kg to minimize fluid overload
- Vasopressors first without fluid bolus
Correct answer: 30 mL/kg of crystalloid IV, then reassess
The Surviving Sepsis Campaign recommends at least 30 mL/kg of IV crystalloid within the first 3 hours of sepsis-induced hypoperfusion recognition.
ABEM Toxicology, Environmental & Infectious Diseases 5
A patient on warfarin presents with an INR of 9.8 and active intracranial hemorrhage.
Which is the FASTEST and most appropriate reversal strategy?