Spirometry results/peak flow

[Allisonc78]

I just got back from an asthma clinic and my peak flow was 380. My normal peak flow was suppose to be 458. But then I took the Spirometry test and my results were FVC 117%
FEV1106 %
FEV1/FVC 90%
FEF25-75% 80%
PEFR 93%

The doctor said my smaller airways were a little more obstructed and could be causing my symptoms lately. My question is how can I still have symptoms with these results and why is my peak flow lower? I am 5'5, 115 and 29. Thank you.

[National Jewish Health]

Spirometry measures the volume and rate of air flow in your larger airways and your results are within the range of predicted "normal values".

Peak flows should be compared, not to predicted normal values, but to your personal best peak flow, that is your peak flow when your asthma is optimally controlled.  You could, as suggested by your doctor, have small airway obstruction with air-trapping and a transient increase in lung volume; this could increase your work of breathing but without much change in the spirometric values.  An alternative explanation would be that, when your asthma is very well controlled, your spirometric values would be better than those listed and this is consistent with the small reduction in peak flow.

It would be appropriate for you and your doctor to step-up your asthma therapy for a few days to see if your symptoms and your spirometric values improve.