Question about positive bronchodilator response in obstructive disease

[SB100]

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Hey guys,

I have conflicting notes from different sources on how to determine if an obstructive disease can qualify as having a positive bronchodilator response. One source tells me that the FEV1 or FVC must increase post-use by >12% or 200ml. Another tells me that the FEV1/FVC ratio must increase by that amount. Which is it?

 

[aggie08]

FVC increase of 10% or more.
FEV1 increase of 200mL or +15% from baseline.
FEF25%-75% increase of 20% or more.

Source: http://www2.nau.edu/~daa/lecture/pft.htm
Scroll down to bullet point VIII.

 

[MediumDef]

Hey guys,

I have conflicting notes from different sources on how to determine if an obstructive disease can qualify as having a positive bronchodilator response. One source tells me that the FEV1 or FVC must increase post-use by >12% or 200ml. Another tells me that the FEV1/FVC ratio must increase by that amount. Which is it?

In short there is not a really great answer. People use varying numbers in different studies . The ATS looked at spirometry interpretations in '91 and decided (+) bronchodilator response should be 12% or 200ml but really any reasonable value can probably be justified so that's probably why you get conflicting data.