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strange findings!

I was taking my peak flow yesterday and just wondering why I always get higher at the gp, than I get at home. First I though it was just down to the pf meter, but then I thought, hang in the cardboard tube at the gp, is wider than the plastic mouthpiece I have on mine. So the scientist in me thought, hmm experiment. So blow on the plastic mouthpiece, get 450, take mouthpiece off and seal lips round the bit that's left, get 500.

Now am I doing something wrong, or is the size / shape of the mouthpiece influencing the pf result? My highest at home reading is 550, at the gp it is 570.

4 Replies

I've always wondered the same thing because my PF is lower at home, and I'd got a vague idea that, like any mechanism, the well used meter at the surgery has a certain amount of wear which means that it moves more easily and gives a higher reading (does that make sense?) I like your idea about the size of the mouthpiece, though - you've clearly thought about it more deeply than I did.

Anyway, whatever the reason for it, I came to the conclusion that the best thing I could do would be to take my own meter with me to the GP so that my readings are always consistent.


I've found this, but I wasn't sure if I trusted it given my technique is variable anyway, and if I'm struggling I can have variation between blows. Not sure how it works but perhaps on the basis that narrowed airways tend to mean a lower PF, a narrowed device might also lead to a lower reading?

Good idea re taking own meter, will have to remember that!


probably because at home you are doing it AM and PM, BEFORE you take your meds. By the time you have it done elsewhere, you have had your inhalers and any other meds.

When I have LFT's I cant have my inhalers that morning. My readings are then very similar to home.

Lynda :)


I've often wondered about this! Surely it can only be accurate if you use the same pf meter for every measurement. Otherwise it's like doing a scientific experiment but always using a different set of scales or something!

I really noticed it last time I went to see the nurse. I was struggling so took my pf that morning and got 360. I walked a mileish uphill to the health centre and apparently got 400! It confused me because I definitely felt worse and the nurse looked concerned and asked me if I was ok.

Unfortunately my nurse only paid attention to pf so sent me away and told me to take it easy. In future I Kay take my own pf meter with me. Maybe even compare the results on mine and hers!


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