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Drastically different PFTs?

I'm going to my doctor this week but wanted to get a head start to see if anyone knows anything with my situation.

I've had "childhood asthma" but no symptoms since I was around 8 or 9. I've taken 2 methacholine challenge tests and an exercise challenge test and was negative for all tests.

Here is the kicker, I just went to an Air Force hospital for a PFT which included plethysmography, DLCO, and slow vital capacity tests. All tests which I have taken before with normal results. But this test that I took at the Air Force facility came back with extreme numbers on the plethysmography and they re-diagnosed me with severe asthma! Is there ANY chance that this test was bunk and had bad patient effort?


  1. Hi AF, and thanks for your post!

    You may be aware we cannot provide medical advice or diagnostics over the internet (for your own safety), but your concern certainly warrants a reply.
    Generally speaking, it would be unusual for someone to have a normal PFT (inclusive of 2 methacholine challenges and an exercise challenge), be asymptomatic and then have a such a dramatic change in test results. It is entirely possible the test was not performed properly, the equipment was not calibrated, you may have not given a good effort and a host of other reasons that would require explanations.
    I would suggest you take this up with your regular pulmonary physician and discuss this thoroughly. If you are symptom-free and are feeling well, at the very least, I would think the PFT should be repeated.
    What do you think?
    Leon (site moderator asthma.net)

    1. Hi Leon, thank you for the reply. Again like I mention, this was performed at an Air Force facility. Particularly for pilot applicants. So I am surprised that such an abnormal PFT with supporting history of methacholine and exercise challenge tests was viewed with such credibility, especially after a normal PFT with plethysmography was performed last year.


      I really want to explore options at this point of what you described. Could anything have affected the results - different mouthpiece, poor coaching, fixed mouthpiece vs handheld, poor instructions. I will keep everyone updated when I visit my pulmonologist sometime this upcoming week.


    2. Hi again, AF - it's our pleasure to be of assistance and support. I think you are on the right track here - looking into this further. Was this the same PFT laboratory that performed your other diagnostics studies? The same therapist who administered the test? All those that you mentioned can also certainly have a bearing on the test results.
      Glad to hear you plan on seeing your pulmonologist this coming week - this is the type of diagnostic result one should be able to rely on.
      As previously mentioned, if you are asymptomatic and feeling well, with no other significant changes in your state of health - this warrants an objective assessment and answer.
      I will look forward to hearing from you again.
      Good luck!
      Warmly,
      Leon (site moderator asthma.net)

  2. This was the same facility where I passed an exercise challenge test. I know that that test doesn't show the same data as a plethysmography, but I am a little shocked how it didn't matter to them at all, along with the 2 methacholine challenge tests that came back negative. And it was a different technician. It was the first time I took a plethysmography in an enclosed chamber, first time doing it on a fixed mouthpiece, first time having to make sure I bite down on the mouthpiece to keep a seal. Part of me wonders if I was focusing too much on biting down than blowing. Anyway, I will report back with my findings hopefully sometime next week. Thanks for the support!


    1. Hi again, AF - sounds like the plan is in place!
      I'm sure you will get some kind of response once you look into this more completely. Stay at it!!
      Have a good holiday tomorrow!
      Leon (site moderator asthma.net)

    2. Just want to say my heart goes out to you and I hope there is some avenue available to you for appeal, especially given your previous tests were solid. No matter what happens, we are here to support you. I hope your persistence pays off! Thank you for your desire to serve! My father-in-law is retired USAF, and one of my best friends is a USAF captain. 😀 Keep us posted! -Melissa, asthma.net team

  3. Hi everyone, thank you for the encouragement. I was able to talk to a pulmonologist and a tech and they are baffled at my situation. Took another PFT and plethysmography and everything came back normal. They kept stressing to me how important patient effort is during these tests. That begs the question - why are Air Force doctors so adamant about this and saying it has nothing to do with effort? Anyway I have my first piece of evidence in this fight. I am going to try and talk to some flight surgeons in the Air Force to see if I can build a case and fight it.


    1. Hi again, AF-Hopeful, and thanks for following up with us here. It's gratifying to hear you have been given the objectively proper information - namely, that among other factors, patient effort is a big one!
      I am so glad to hear this most recent PFT with plethysmography came back normal for you. You also must be relieved to hear this.
      As you move forward with your inquiry, please do check back and let us know how it all turns out for you.
      Once again, thanks for your input and your feedback, too.
      Leon (site moderator asthma.net)

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