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COPD

Hi everyone,

basically I know that the reason that patients with bronchitis are cyanosed due to a low V:Q ratio I'm confused about emphysema.
I've read conflicting sources, for example, cheese and onion (oxford handbook of medicine) states that in emphysema ventilation is increased where as in "Pathophysiology of pulmonary disease" it states that ventilation in emphysema is decreased. Both sources agree on the fact that perfusion is reduced.

Does anyone have an answer as to which source is more correct, and also why they disagree? I understand the first source (increased ventilation) but I'm confused as to how the other book can say that ventilation is decreased, especially when patients with emphysema are hyper inflated?

Many thanks,

Charles :smile:

Reply 1

Beska

They might be talking about the fact that actual movement of gas is reduced in emphysema due to air trapping, thus technically reduced ventilation even though there is gas there. In emphysema anyway it's a poor gas transfer medium due to loss of surface area of exchange surfaces, probably that paired with the air trapping means there's a net reduction in ventilation.