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Old 03-23-2013
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Lungs Expiratory Flow Rate in Restrictive Lung Disease!

In "restrictive" lung Dz
Why the "expiratory flow rate" increase due to decrease "lung compliance".
I mean what's the relationship btw compliance and expiratory flow.

Thank u guys
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Old 03-23-2013
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You know that confused me as well, but here is another way of looking at it. In fact the flow rate is actually reduced, but what isnt reduced is the ratio. The FEV1/FVC ratio. That ratio is either increased or its normal.

Wikipedia lays it out pretty clearly: "In restrictive lung disease, both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are reduced, however, the decline in FVC is more than that of FEV1, resulting in a higher than 80% FEV1/FVC ratio" . Its just the rate of decline that is more in FVC than FEV1.
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Old 03-23-2013
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Quote:
Originally Posted by CisternaChyli View Post
You know that confused me as well, but here is another way of looking at it. In fact the flow rate is actually reduced, but what isnt reduced is the ratio. The FEV1/FVC ratio. That ratio is either increased or its normal.

Wikipedia lays it out pretty clearly: "In restrictive lung disease, both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are reduced, however, the decline in FVC is more than that of FEV1, resulting in a higher than 80% FEV1/FVC ratio" . Its just the rate of decline that is more in FVC than FEV1.
just to add to CisternaChyli's post .. here's how i think of it

in restrictive, the ptn has a problem with filling up the lungs (decreased compliance)and they have low lung volumes.. so when they huffed for the first second, they got all the air out (it's still decreased though) and nothing left for the FVC (even more decreased than FEV1) so higher ratio (or normal).

same idea can be applied to obstructive
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Old 03-23-2013
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Quote:
Originally Posted by ` Faith ` View Post
just to add to CisternaChyli's post .. here's how i think of it

in restrictive, the ptn has a problem with filling up the lungs (decreased compliance)and they have low lung volumes.. so when they huffed for the first second, they got all the air out (it's still decreased though) and nothing left for the FVC (even more decreased than FEV1) so higher ratio (or normal).

same idea can be applied to obstructive
yeah thats also a good way of looking at it . Yeah there isnt much volume there to begin with. In obstructive, the volume is there, but they arent able to get much of it out, so thats why you see a decreased FEV1, but a stable FVC.

I know Wikipedia is kinda frowned upon, but its actually a pretty decent source if Kaplan or FA doesnt have something.
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Old 03-24-2013
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Now it makes sense for me
Thank u CisternaChyli and ` Faith `
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Pathology-, Physiology-, Respiratory-

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