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Question:
An 18-year-old woman has gastroenteritis with nausea and vomiting and is able to ingest only small amounts of water. After 3 days, she develops light-headedness, especially when sitting or standing. Arterial blood gas analysis is most likely to show which of the following sets of values?
Correct Answer: E. pH 7.50, pCO2 47, HCO3 35
Due to the vomiting, this woman is losing HCl (the main stomach acid). Since she is unable to control the vomiting and is not eating she cannot adequately compensate for the acid loss. Therefore, she is in a state of metabolic alkalosis (pH>7.40) which eliminates options A, B, and C. Although her kidneys will eventually compensate by excreting HCO3, this process takes about a week to compensate, and therefore HCO3 will be increased (>24). In order to compensate, the respiratory drive decreases so that the body retains more CO2, and therefore pCO2 is increased (>40). Only option E has increased pH, pCO2 and HCO3.
Option A is metabolic acidosis
Option B is respiratory acidosis
Option C is Normal
Option D is respiratory alkalosis
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1. Question
Category: PhysiologyAn 18-year-old woman has gastroenteritis with nausea and vomiting and is able to ingest only small amounts of water. After 3 days, she develops light-headedness, especially when sitting or standing. Arterial blood gas analysis is most likely to show which of the following sets of values?
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