Below is an instruction that describes a task. Write a response that appropriately completes the request. ### Instruction: Hey guys,Today I had a pulmonary function test performed and results are mostly normal, which I expected. The only abnormal result is my FEF25-75%. The final value was 2.04, 64% of the expected reference value.I didn't have a bronchio dilator test performed due to palpitations, which I take beta-blockers for. Still being studied in cardiology.I didn't expect much to come out of this, because my GP suspects it might be exercise induced asthma. I wasn't feeling particularly bad when I had the test performed either.I experience chest tightness, wheezing, sob, air-way burning feeling and it hurts when I try to take a deep breathe. If I talk too much or laugh, I also get chest pain and cough.I have been prescribed Atrovent/Ipratropium bromide and it's so far the only thing that has helped me. It has taken me from barely being able to walk 40-50min, to walking 40-90min (usually 40-60) depending on the day without collapsing.. ### Response: The FEF25-75 is the forced expiratory flow throughout the middle of your expiration. When we fully exhale our lungs are left with some air leftover (called residual volume, or RV on your PFT). This RV is there because as we exhale our small airways close down as the intrathoracic pressure rises above the intra-bronchiolar pressure -- it's a normal part of expiration. A lower FEF25-75 is thought to reflect early small airway closure, which could be a component of asthma (as asthma affects small airways).You'll notice I use a bunch of hedgy language (lots of "could" and "thought to"). PFT guidelines recommend against using FEF25-75 to diagnose or treat anything. The data just isn't very strong. The American Thoracic Society recommends not even putting the FEF25-75 on the PFT report. All that said, the FEF25-75 isn't entirely worthless, it just has to be interpreted with caution. If you have the right symptoms, a reduced FEF25-75, and a positive clinical response to bronchodilators it can be very reasonable to suspect asthma.If you have a great response to the inhaler, great, there's your answer. If not, it would be a reasonable time to seek an evaluation by a pulmonologist. Your goal should be feeling normal. All-too-often asthmatics will talk about having daily symptoms, which is a real shame. They either need more aggressive treatment or a different diagnosis altogether..