ABEM Toxicology, Environmental & Infectious Diseases 4

Question 1

A scuba diver surfaces too quickly and develops joint pain, dyspnea, and marbling of the skin. Which chamber pressure is used in hyperbaric oxygen therapy for decompression sickness?

Accepted Answer

2.8 ATA

Answer

US Navy Treatment Table 6 uses 2.8 ATA with 100% oxygen to maximize bubble reabsorption and treat decompression illness.

Question 2

A 30-year-old with fever, painless ulcer on the penis, and bilateral inguinal lymphadenopathy is diagnosed with primary syphilis. He has a documented penicillin allergy with anaphylaxis. What is the recommended alternative?

Accepted Answer

Desensitization followed by penicillin G benzathine

Answer

Penicillin G benzathine is the only proven treatment for all stages of syphilis; in penicillin-allergic patients with primary syphilis, doxycycline is acceptable but desensitization is preferred in non-pregnant patients with neurosyphilis or pregnancy.

Question 3

A patient with fever and rigors after returning from sub-Saharan Africa has a peripheral blood smear showing ring-form parasites in >5% of RBCs with multiple parasites per RBC. Which malaria species is most likely?

Accepted Answer

Plasmodium falciparum

Answer

Plasmodium falciparum causes high-density parasitemia (>5% RBCs infected), multiple ring forms per cell, and is responsible for cerebral malaria and life-threatening complications.

Question 4

A patient presents with descending flaccid paralysis, dry mouth, diplopia, and ptosis after eating home-canned green beans. Autonomic function is preserved. Which toxin mechanism is responsible?

Accepted Answer

Blockade of presynaptic acetylcholine release at the neuromuscular junction

Answer

Botulinum toxin cleaves SNARE proteins, blocking presynaptic acetylcholine vesicle release at the neuromuscular junction, causing flaccid paralysis.

Question 5

Which of the following is a reliable clinical feature distinguishing heat stroke from severe heat exhaustion?

Accepted Answer

Central nervous system dysfunction

Answer

CNS dysfunction (altered mentation, seizures, coma) is the defining feature of heat stroke and differentiates it from heat exhaustion, where cognition remains intact.

(ABEM) American Board of Emergency Medicine Practice Test

(ABEM) American Board of Emergency Medicine Practice Test

ABEM Toxicology, Environmental & Infectious Diseases 4