A patient breathing room air has PaO2 60 mmHg and PaCO2 48 mmHg. Using PAO2 = 150 - PaCO2/0.8, what is the A-a gradient?
Answer and explanation
Correct answer: D. 30 mmHg
- Step 1: PAO2 = 150 - 48/0.8 = 90 mmHg.
- Step 2: A-a gradient = PAO2 - PaO2 = 90 - 60 = 30 mmHg.
Answer
30 mmHg.
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