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Value of MEF25-75 on Spirometry

I have been reading over some patient answers from great Dr Tom Petty on the old Yourlunghealth website.

Dr Tom constantly refers to the MEF25-75 of being no value and the only values that matter are the FEV1 and FVC. I'm puzzled by this but appreciate things change by the hour never mind the decade.

I ask this question in the context of an FEV1 of 106% and an FVC of 113% with an MEF75 of 69% and an MEF of 92 post bronchodilator.

Is this correct or not about the MEF range being of no relevance?

  1. The way I see it is that if you have symptoms in the face of normal FEV1 / FVC etc the mid range is of value. If you’ve no symptoms with the same results they’re of little value.

    1. Thanks for responding Leon, I will take it up for certain. It is indeed confusing when different opinions are considered. I did also find this interesting article on the PFT blog.


      https://www.pftforum.com/blog/it-it-time-to-scuttle-the-fef25-75/


      1. Hi again, Cruzer, and thanks for sharing the article from the blog. You make a good point, about how you analyze the FEF 25-75. Have you had an opportunity to discuss your results with the physician who prescribed the PFT test to begin with?
        This doctor would be the best individual for you to discuss your results with at length. He/she should be able to address your concerns about the results and how to view the mid-range flow rate data.
        If you are able to have that conversation, please do check back and let us know how this all works out for you.
        All the best,
        Leon (site moderator COPD.net)


    2. Hi Cruzer, and thanks for this post. With all due respect to you (and Dr. Thomas L. Petty, too), I have not heard of an MEF 25-75, when it comes to pulmonary function testing and flow rates.
      Is it possible you meant to say FEF 25-75? That would be forced expiratory flow rate (FEF), and is well known as a gauge for the severity of obstruction when used in conjunction with FEV1 and FVC results and ratios (which you mentioned).
      If this is what you are referring to, the best person for you to ask about its significance in your particular case, would be your physician or pulmonary specialist.
      What do you think?
      Leon (site moderator COPD.net)

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