Question 1

Q: A 62-year-old man is brought to the emergency department with a 2-day history of cough productive of yellowish sputum. He has had fever, chills, and worsening shortness of breath over this time. He has a 10-year history of hypertension and hyperlipidemia. He does not drink alcohol or smoke cigarettes. His current medications include atorvastatin, amlodipine, and metoprolol. His temperature is 38.9°C (102.0°F), pulse is 105/min, respirations are 27/min, and blood pressure is 110/70 mm Hg. He appears in mild distress. He has rales over the left lower lung field. The remainder of the examination shows no abnormalities. Leukocyte count is 15,000/mm3 (87% segmented neutrophils). Arterial blood gas analysis on room air shows: pH 7.44 pO2 68 mm Hg pCO2 28 mm Hg HCO3- 24 mEq/L O2 saturation 91% An x-ray of the chest shows a consolidation in the left lower lobe. Asking the patient to lie down in the left lateral decubitus position would most likely result in which of the following?

Increase in A-a gradient. ***Increase in A-a gradient*** - Placing the patient in the **left lateral decubitus position** would worsen V/Q mismatch because the **diseased left lung** (with consolidation) would receive increased perfusion due to gravity. - This increased perfusion to a poorly ventilated area would further impair gas exchange, leading to a larger **alveolar-arterial (A-a) gradient**. *Decreased ventilation of the left lung* - While lying on the left side might slightly restrict the expansion of the left lung, the primary issue is the **consolidation** itself, which already severely impairs ventilation. - The main problem with positioning is not a further decrease in ventilation but rather the **redistribution of blood flow** to an already compromised lung. *Worsen the hypocapnia* - The patient has **hypocapnia (pCO2 28 mm Hg)** due to tachypnea as compensation for hypoxemia, indicating increased minute ventilation. - While worsening the V/Q mismatch will worsen hypoxemia, it's unlikely to directly worsen hypocapnia further; the body would still try to compensate through increased respiratory drive unless the respiratory muscles become fatigued. *Increased perfusion of right lung* - In the left lateral decubitus position, **perfusion due to gravity** would increase in the dependent (left) lung, not the non-dependent (right) lung. - The right lung would experience relatively decreased perfusion compared to the left lung in this position. *Improve the hypoxemia* - Lying on the side of the **diseased lung** (left) typically **worsens hypoxemia** because gravity directs more blood flow to the poorly ventilated, consolidated lung. - To improve hypoxemia, the patient should be positioned with the **healthy lung dependent** (e.g., right lateral decubitus or semi-Fowler's with the right lung lower) to optimize V/Q matching.

Question

A 62-year-old man is brought to the emergency department with a 2-day history of cough productive of yellowish sputum. He has had fever, chills, and worsening shortness of breath over this time. He has a 10-year history of hypertension and hyperlipidemia. He does not drink alcohol or smoke cigarettes. His current medications include atorvastatin, amlodipine, and metoprolol. His temperature is 38.9°C (102.0°F), pulse is 105/min, respirations are 27/min, and blood pressure is 110/70 mm Hg. He appears in mild distress. He has rales over the left lower lung field. The remainder of the examination shows no abnormalities. Leukocyte count is 15,000/mm3 (87% segmented neutrophils). Arterial blood gas analysis on room air shows:
pH 7.44
pO2 68 mm Hg
pCO2 28 mm Hg
HCO3- 24 mEq/L
O2 saturation 91%
An x-ray of the chest shows a consolidation in the left lower lobe. Asking the patient to lie down in the left lateral decubitus position would most likely result in which of the following?

Accepted Answer

Increase in A-a gradient

Answer

Decreased ventilation of the left lung

Answer

Worsen the hypocapnia

Answer

Increased perfusion of right lung

Answer

Improve the hypoxemia

V/Q mismatch — MCQs

V/Q mismatch — MCQs

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