FEV1 test for Affrezza: best method, interpretation?

I already posted here that I have received our self-test spirometry meter to perform regular FEV1 tests for Afrezza. A few questions for those who have been through the procedure in a lab setting:

  • what are the instructions you were given to obtain as repeatable numbers as you can? I have read in several places that getting repeatable readings sometimes takes some instruction.

  • does anyone know the official US guidelines to interpret readings? I have found scales to interpret normal PEF and FEV1, but I have not been able to find the official US/Canadian guidelines.

What I have found online so far

  • Calculator of normal predicted values:


  • Normal PEF (Peak Expiratory Flow) ranges, depends upon height, gender, age, should not be used for diagnosis since there is too much variability
  • Normal FEV1 (Forced Expiratory Volume in 1 second) ranges, depends upon gender & age, can be used for diagnosis in combination with other numbers (Forced Vital capacity FVC):

[check diagram at the lower left]

  • GOLD system to measure asthmatic impairment or COPD (chronic obstructive pulmonary disease):

I may be partially answering my own question here :slight_smile:

Here is a CDC calculator for expected values:


Here is a healthline generic write-up about the procedure:

I would still like to read more about what others know on this, in particular the best procedure instructions.


The procedure I did required that I breathe normally for 5 seconds or so and then inhale deeply, breathe out all the way, then inhale deeply again. The test administrator said that breathing normally for a few seconds enabled them to develop a baseline. I don’t know how that impacted my results though.

She told me exactly when to start the deep inhale and when to breathe out. Timing that was the more difficult part. The results sheet she gave me looks very similar to the calculated values section on the bottom of the page you linked. In addition, there are a couple of graphs, but I have no idea what they mean.

If it’s helpful, I’m happy to send the graph and results to you. Just let me know.


Entirely too much is being read into this… the spirometry is a joke.

You breathe in and then breathe out into the measuring device as hard and as fast as you can. The expected value is pretty much a joke, they look at the curve instead. If the fev1 is less than 70% of expected value they have someone who actually knows what they’re talking about look at the curve and the ratios to other measurements …

In meaningful context, the test was required to ensure that with long term use patients lung volume wasn’t significantly decreasing with afrezza use… which hasn’t turned out to be a thing…

For a screening, they told me they want to see an fev1 above 70% of expected to ensure it was “normal” and if it was below that they’d actually want the pulmonologist to examine you to rule out any issues, although normal healthy people do score low sometimes just due to anatomical differences…


I think this is why home testing isn’t likely to be very meaningful… say you do get a marginal result… what does it mean? A real pulmonologist might evaluate it, and the patient… and might say oh well actually in context this is even higher than I’d expect for someone with his physical characteristics, chest size vs height, ethnicity, blah blah blah (whatever it may be that someone who knows this stuff knows that we don’t)… all results have to be evaluated in context… if you’re evaluating results and don’t know context it’s not necessarily a good thing…

I agree with @Sam - it is a joke. My “Afrezza Endo” (yes, I use different endos for different things) has my baseline from 2 years ago, and when I asked him about a follow-up, he told me he never repeats the test because it is too variable - even with a pulmonologist.

My first test recorded an FEV1 at 73%. The pulmonologist who read the results said I have the lungs of a 72 yo and “failed” the test. The instructions he gave me was to pretend I was blowing out candles on a birthday cake. Well, I tend to blow slow and long in that situation - so bad instructions and invalid result.

My internist did one recently, and she ignored the percentage. It is obvious she doesn’t know what to look for, nor the variability. I had 83% on that test.

On home testing, on a professional machine, I see between 70-105%. Depends on lots of things: do I have a cold, did I breath in deeply enough, did I exhale long enough, etc. If I do 2 years in a row, I can get vastly different results.

In general, I find my results to be similar from test to test when I look at average tends. This is all I care about.

For the record, my machine requires 5 consecutive tests for a result and averages them.

I guess my overall comment is that home monitoring isn’t bad, and you may see if a major problem occurs, but even done on the doctor’s office, they are too variable to mean much.


@kmichel, do you have a method you use?

My son is having trouble generating consistent readings.

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It is kind of like monitoring weight. Watch the average tends. That said, I sit at a table with feet flat on the floor. Relax, breath a few normal breaths, and with my hand y abdomen to ensure I fill it well, I take a deep breath. Exhale as much as possible as quickly as possible from the abdomen, then the upper chest.

My machine requires a 6 second exhale, but I try to exhale everything in that 1 second. I am drained for the last 5


That’s a great tip, thank you!

I understand what you mean. the variability on both the PEF and the FEV1 seem higher than you’d like them.

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Here are a couple articles I saved when I started looking at Afrezza:

Good explanation of differences in values, and causes:

Good video explanation of doing the test properly, and interpreting the results:


This is why imo home testing is a poor idea… I’m afraid people will test constantly and read way too much into the results and incorrectly assume clinical significance where there is none…

Also think it has potential to be relatively psychologically unhealthy… like sending a teenage girl with an eating disorder home with a scale and a puke bucket and telling her to watch her weight…

Eh. I still think of it being more like weighing yourself daily. You can’t get bent out of shape on the gains and losses, rather you have to look at tends.

The clinical tests are no more stable.

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But look at how many people do get bent out of shape over daily weight fluctuations… even though it isn’t really reflective of the true trend… people aren’t always rational

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I agree. But what to do? Been scales except at doctor’s offices? :wink:

If a person misinterprets the information their scale gives them and makes harmful decisions based on that info, then I’d suggest it might not be in their best interest to own one. That’s not to say that everyone would… I’d suggest the same is true for home spirometry monitoring, although I’d be willing to bet that latter is more likely amongst the people who own them…

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Sam, I understand your concern, but in some ways it echos the concern that medical professionals were having with the idea of giving unblinded CGMs to patients. The patients might check their BG 30 or 40 times per day (oh the horror) and worse yet, make treatment decisions based on the excessively frequent BG data. I’m generally in favor of having data except in cases where it is actually causing a problem.


I agree with @bkh. I refuse to have medical professionals make decisions for me. I want them as my valued advisers, but I expect to make the decisions, and I need to see the data. Data is always good! I don’t want anyone keeping data from me because “it is unhealthy for me to see it.” So I don’t even mkae the exception. Data should always be the patient’s in my mind.

Do you know that, in France, medical professionals are not obliged, ethically, to tell patients they are dying? How crazy is that: the ultimate data may be hidden from you, and hiding it from you is ethical. In my mind, all my medical data belongs to me, and it is up to me to decide if I want to use it or not—but nobody else should have that right.

I think it should be up to them to make that decision.


@kmichel, thanks so much for the links, they are excellent. When I have a day with some free time, I will try to put together a wiki on this.

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It should be, and it is, and that should never change

Still doesn’t mean it’s necessarily in their best interest


I know re: scales, I think often people really don’t need or benefit from home scales—most people can track weight gain to the extent necessary based on how their clothes fit (which also does a better job of figuring in the whole muscle is denser than fat thing in terms of tracking improvement in fitness). If it works for a person to own and use one, fine of course. For many people, it causes more stress/reactivity to non-meaningful changes than help.

I could be convinced that home FEV tracking could be similar depending on the ratio of signal to noise—you need a pretty strong/meaningful signal in there (assuming actual, not perfect, measurement) for it to be worth it.

I definitely think all the data with CGM takes some getting used to and that the data has the ability to cause problems especially if people aren’t well prepared for the potential pitfalls—initially for me, it drove rollercoasters until I learned not to overtreat both highs and lows while waiting for whatever I did to kick in, no matter if the CGM was still yelling at me. That said, no way in hell would I have signed up for the blind version ever with only my doctor seeing the results.