ventilation/Perfusion

[Can2carib]

In first aid, they say that ventilation and perfusion are both better at the base of the lungs. I though perfusion is better in the lower lobes but ventilation was better in the upper lobes. Goljan says ventilation is better in the upper lobes to.

Or is it just that ventilation is better than perfusion in the upper lobes and perfusion is better than ventilation in the lower lobes. However, overall, perfusion and ventilation are better in the lower lobes?

Help would be appreciated..

[Dr. X]

In first aid, they say that ventilation and perfusion are both better at the base of the lungs. I though perfusion is better in the lower lobes but ventilation was better in the upper lobes. Goljan says ventilation is better in the upper lobes to.

Or is it just that ventilation is better than perfusion in the upper lobes and perfusion is better than ventilation in the lower lobes. However, overall, perfusion and ventilation are better in the lower lobes?


You are definitely on the right track.. esp. your 2nd paragraph. heres my input.

ventilation is lower at the apex (smaller) compared to the base (larger) because of regional differences. Goljan points out that the air going to the upper lobe sticks around longer than the air that goes to the lower lobes. Overall, the ventilation is better/higher at lower base.

perfusion is better at base of lung than the apex simply because of gravitational effects.

the key is to understand the V/Q differences.

Apex: ventilation is lower but the perfusion is even more low making the V/Q mismatch greater. This comes out as "better GAS exchange" at apex.

Base: ventilation is higher but the perfusion is even more higher making the V/Q mismatch lower. This comes out as "lesser GAS exchange" at base.

then comes the pathology part which im sure you could work through since you got the physio down.

[Can2carib]

Thanks Dr. X....makes total sense now