USMLE Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
741 Posts
Discussion Starter · #1 ·
The DLco can be a nice buzzword in CK exam cases. They usually give it to help us reach a specific diagnosis. Therefore, it's a good idea to know something about it.

It measures the diffusion capacity of the lung of CO. Values less than 75% is considered decreased and values above 120% is considered increased.

Causes of Decreased DLCO:
Then you have to look at the FEV pattern to determine the cause;

  • If you have a restrictive pattern in the FEVs then think of restrictive lung diseases such as fibrosis, pneumonitis, elveolitis, idiopathic pulmonary fibrosis, Bleomycin therapy ...etc
  • If you have an obstructive pattern in the FEVs then think of emphysema.
  • If you neither have a restrictive nor an obstructive pattern (such as the question did not mention about it) then think either pulmonary embolism or pulmonary hypertension.

Causes of Increased DLCO:
This is rarely tested but I mention it here for completion
- the cause is usually an increased pulmonary blood volume examples are; exercise, congestive heart failure, and pulmonary hemorrhage.
- Asthma also may increase the DLCO
- Smoking
- Polycythemia (of course you have more hemoglobin to exchange the CO with the alveolar space)

Another interesting condition is extrathoracic restriction (for example fracture rib or abdominal distension) this will cause a restrictive pattern in the FEVs yet there's normal DLCO ;)
 

·
Registered
Joined
·
51 Posts
Chronic bronchitis has normal DLCO, emphysema has decreased DLCO
yes, actually the way I remember it is thinking of Chronic bronchitis as a kind of Asthma related pathology...
 

·
Registered
Joined
·
1 Posts
DOUBT : early vs late onset dyspnoea

Hypoxemia occurs early in chronic bronchitis but dyspnoea occurs late and vice versa for emphysema
Can someone please explain why

Thanks :)
 
1 - 11 of 11 Posts
Top