A 48-year-old woman with HTN, T2DM and an ex-smoker has dyspnoea after 2 blocks, distant heart sounds, trace oedema. ABG: pH 7.30, PaCO2 55, PaO2 70, HCO3 31, A-a gradient 8. What is the cause of her dyspnoea?
سؤال مجاني 10 من 10 اليوم · اشترك وكمّل بدون حد
اعرض الإجابة
الإجابة والشرح
ادخل لحسابك عشان نحفظ إجاباتك ونوريك أخطاءك.
الإجابة: B. Alveolar hypoventilation
PaCO2 55 (hypercapnia) with only mild hypoxaemia and a normal A-a gradient (8) → the lungs exchange gas normally, so the problem is alveolar hypoventilation (an extrapulmonary cause). V/Q mismatch, shunt and bronchospasm are lung problems that raise the A-a gradient.
ليش كل خيار صح أو غلط
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A
ليش غلط
Bronchospasm/obstructive disease causes V/Q mismatch, which raises the A-a gradient. Hers is normal (8), so the lungs are not the problem.
✓ ABG & A-a gradient.pdf · p. 3 -
B
ليش صح
A normal A-a gradient (normal 5-10) points outside the lungs; hypoventilation (CNS/neuromuscular causes) has no diffusion defect. Her high PaCO2 fits.
✓ ABG & A-a gradient.pdf · p. 3 -
C
ليش غلط
Right-to-left shunting is listed among the causes of an increased A-a gradient. Hers is normal (8).
✓ ABG & A-a gradient.pdf · p. 3 -
D
ليش غلط
V/Q mismatch is a lung cause of an increased A-a gradient (e.g. PE, pneumonia, obstructive disease). Her A-a gradient is normal at 8.
✓ ABG & A-a gradient.pdf · p. 3
- المصدر
- ABG & A-a gradient.pdf · p. 3
11• Respiratory Failure [Slides].pdf · p. 2 - المحاضرة
- Respiratory Failure & Acid–Base · Pulmonology · Module B
- ظهر في
- MED41 ♂ EOM B