Question
Lung functions in the lung marked as “A” reveal all of the following ,except?
A. Decreased vital capacity.
B. Increased diffusion capacity for carbon monoxide (DLCO).
C. Increased Total Lung capacity.
D. Decreased FEV.
Show Answer
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Correct Answer » B
Explanation
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THe lung marked as “A” represent emphysema while the lung marked as “B” is a normal functioning lung.
Emphysema is associated with a decreased diffusion capacity for carbon monoxide
Lung Function Tests in Emphysema
TLC : Normal or Increased
FEV : Decreased (< 80% predicted) (Decreased out of proportion to FVC)
FVC : Decreased
FEV1 / FVC : Decreased (< 0.7)
FEF25 – 75 : Decreased (
DLCO : Decreased
Note that DLCO is normal in other obstructive lung diseases like chronic bronchitis
Diffusion capacity for carbon monoxie (DLCO)
Diffusion capacity is altered in disease affecting the functional integrity of the alveolar capillary membrane.
In Emphysema, alveolar walls are destroyed, so the surface area of alveolar–capillary bed is diminished resulting in diminished DLCO.
Three main disoders are associated with lowerd DLCO
- Emphyseinae
- Interstitial Lung Diseasee
- Pulmonary vascular disease (Recurrent Pulmonary emboli or Primary Pulmonary Hypertension)Q
