Arterial blood gases MCQ

1. A 25 year old man is seen in the Emergency Room following a drug over dose (? Nature). He is semi-responsive. Arterial blood gases show a PaCO2 of 60 mmHg. The elevated PaCO2 signifies:

A. Normal alveolar ventilation
B. Alveolar hypoventilation
C. Alveolar hyperventilation
D. None of the above

2. A 65 year old cigarette smoker with previously diagnosed COPD has the following arterial blood gases on room air: PaCO2 = 40 mmHg. PaO2 = 65 mmHg, and pHa = 7.38. Calculate his alveolar arterial PO2 gradient (A-a DO2):

A. 20 mmHg
B. 15 mmHg
C. 35 mmHg
D. 50 mmHg

3. In a subject with an arterial PCO2 of 30 mm Hg, you would consider which of the following in the differential diagnosis:

A. Acute airway obstruction
B. Interstitial lung disease
C. Pulmonary embolism
D. Diabetic ketoacidosis


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