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Personal Best Peak flow

I managed to get a copy of my spiro results the other day and was surprised by the reading I blew post neb.. Managed 621. Anyway since starting my PF diary the best I have managed is 570. Would I be right in thinking that it's unrealistic to expect to get as good as 620 normally/when having good days etc..? I mean post nebuliser is 'not normal' right?

On an aside, would a non asthmatic have any improvement in PF post neb?

7 Replies

I don't think you can compare spirometry results with the results you get on your normal peak flow meter. Generally you get a bit lower peak flows with the peak flow meter (I think because of the resistance of blowing the little plastic disc).

If your asthma is well controlled hopefully you should be getting at or near your best. I think you are supposed to aim for less than 20% variation in peak flows (sounds like a wonderful dream to me at the moment!).

Not sure about the answers to your other questions- hopefully someone else will know!

Take care



I guess the reason I was asking was wether to go by 20% from the post neb PF as my personal best or the best I've achieved with my PF meter at home.. Just curious really, tho certainly don't feel any urgency with things as they are at the moment.


Even though you can't get the same high reading with the manual one, I'd be inclined to work with the high reading. I have an electronic meter and that reads higher than manual meters.

To answer your last question, possibly but not as much as someone with asthma


Do you know what your predicted peak flow should be? You could use which ever is the highest and then you will be seeking help earlier if your peak flow decreases.

Non-asthmatics will get some variation in peak flow but not as much. The only figures I could find on the internet about pre and post neb spirometry talked about variations in FEV not peak flow. 12% increase after a neb seemed to be the most quoted figure (indicating asthma), however if your asthma is mild and well controlled you won't always see that much variation.


here's an online PF calculator but expect you have exceeded the predicted value already.


same link, just full version below.



Thanks for the replies, yes, I already exceed what is expected. In fact in my spiro my before neb readings were my expected levels (495), post neb was 618. So far, in my PF diary I range from 500 to 570 but admittedly this is with a normal plastic PF meter, not an electronic one..

I find I am mildly symptomatic if my PF is low in the 500's. Yet to have another cold whilst doing the diary. I feel like I am coping fine, some days having more venolin than others, I'm jsut trying to get to grips with the numbers so I know when I should be thinking about speaking to doc/nurse.

Trying to avoid another hellish chest infection like I had through the winter which also put my back out several times because of the coughing.

Thanks for all the comments, I really find all this stuff interesting. :)

For info, if anyone is interested my results were as follows (yet to google what the other measurements mean):

FVC: Pre=4.83 (predicted 4.59) Post=6.67 (go me!)

FEV1: Pre=4.26 (predicted 4.01) Post=4.78

FEV1/FVC: Pre=0.88 (predicted 0.87) Post=0.72 (not sure if it's good that it went down or not really?)

PEF: Pre=492 (predicted 495) Post=618 (more go me!)

FEF25-75: Pre=4.65 (predicted 4.20) Post=2.98 (again not sure why this goes down?)


best peak flow

Hi my best peak flow is 350 and it goes up and down between that and 200 like a yoyo.


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