Is peak flow meter reader an accurate measure of asthma?
Peak Flows are shockingly poor in terms of diagnostics. They are only really useful for the management of asthma as asthmatics can measure how much worse/better they are doing relative to their normal amount and adjust their medication as such – even then they’re pretty limited. The “normal” range is useless on an individual basis. They’re guidelines but perfectly healthy people can be well outside the range, when we were introduced to them there were people that had absolutely no breathing problems scoring well below the “expected value” – that doesn’t meant they have a disease, it just means that the value doesn’t fit them. The value that you can achieve depends on a hell of a lot of things, particularly the motivation you have to beat it. A doctor telling you to blow into it versus a doctor actively encouraging you to push as hard as possible are going to give you very markedly different results. It may just be that you can’t reach the “normal” value even when perfectly healthy, or
