WBR0397

Author	Vendhan Ramanujam
Exam Type	USMLE Step 2 CK
Main Category	Internal medicine
Sub Category	Miscellaneous
Prompt	A deep-sea water diver is brought to the ER with complaints of lightheadedness, dizziness, ataxia, and nausea. He was on a diving expedition to explore sunken ships. He started experiencing these symptoms after reaching 110 ft of depth. Which of the following is the most likely diagnosis?
Answer A	Nitrogen narcosis
Answer A Explanation	Correct-Nitrogen narcosis is due to increased partial pressure of nitrogen in the nervous system; symptoms are analogous to those of alcohol intoxication like lightheadedness, dizziness, ataxia, and nausea. It is a manifestation of compression sickness occurring during descent.
Answer B	Barotrauma
Answer B Explanation	Incorrect-Barotrauma is due to the mechanical effects of expansion and contraction of gases when pressure differences exist between the body cavities and the environment. It is a manifestation of compression sickness occurring during descent.
Answer C	Vertigo
Answer C Explanation	Incorrect-Vertigo (barotrauma) is due to the mechanical effects of expansion and contraction of gases when pressure differences exist between the body cavities and the environment. It is also a manifestation of compression sickness occurring during descent.
Answer D	Barosinusitis
Answer D Explanation	Incorrect-Barosinusitis (barotrauma) is due to the mechanical effects of expansion and contraction of gases when pressure differences exist between the body cavities and the environment. It is also a manifestation of compression sickness occurring during descent.
Answer E	Bends
Answer E Explanation	[[AnswerEExp::Incorrect-Bends (so called because the person can be stooped due to severe joint pain) are a form of decompression sickness (also called caisson disease) due to inadequate elimination of dissolved gas after a dive affecting the skin and joints. Decompression sickness can occur either after a too-rapid ascent from a dive below 9 m or a sudden pressure loss at altitudes above 7000 ft.]]
Right Answer	A
Explanation	[[Explanation::Nitrogen narcosis is due to increased partial pressure of nitrogen in the nervous system; symptoms are analogous to those of alcohol intoxication like lightheadedness, dizziness, ataxia, and nausea. It is a manifestation of compression sickness occurring during descent. Educational Objective: Manifestations of compression sickness are nitrogen narcosis, vertigo, barosinusitis, middle ear or barotitis media that occur during the descent of a drive. Decompression sickness (also called caisson disease) occurs during the ascent of a dive. Educational Objective: References: ]]
Approved	Yes
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