Dr Andy post today about peak flow

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Hi everyone

If you're on the Asthma UK mailing list you may have got an email today from Dr Andy about using your Peak Flow to record symptoms.

I find my PF doesn't really reduce when my asthma kicks off, but it is very informative and useful. But I would just add one thing and I don't know if anyone else finds this - different peak flow manufactures give different readings. I used a Mini-Wright meter for years and the last few times I've been prescribed a new one I got a blue one (can't remember the manufacturer) and a flat grey one (again can't remember the brand) and they both give readings that are 50-80 litres higher than the MW. This gives the false impression my asthma has improved and it means the scores I show at my appointments are not consistent. So I've had to go back to my old MW until I can get another one. Just something to keep in mind if anyone else has found their PF score has suddenly improved!

[DeanSamson]

My peak flow never really changed even when I'm feeling bad it still stays around 560. I can understand how it can be a good indication for some people. 😊

[Lysistrata Administrator Community Ambassador]

Thanks for highlighting this. A small blue one I was given in hospital last year is usually consistent with the mini-Wright. However, I've found digital meters especially have this discrepancy - for me they're usually at least 50l higher than MW, and of course they use those in clinic without accounting for my personal best also increasing Vs MW.

[twinkly29]

Agree that in some people peak flow doesn't really change when struggling - a good point because if someone was waiting til it dropped that could be dangerous!

Doing peak flow before reliever medication and about 15 mins afterwards can be really useful though as it can show if symptoms are likely to be asthma or not. Obviously it's not a black and white situation but generally speaking if peak flow never increases even with ventolin, then it's suggestive of alternative reasons for the symptoms. Even in those whose PF doesn't drop much when struggling, it should still increase with reliever medication if it's asthma.

Similarly, if peak flow is always pretty much the same and preventers (once given their kicking in time) don't have a positive impact on it, then other diagnosis options need to be explored.

But measuring peak flow regularly (usually twice a day before inhalers) can provide good evidence for reviews or if there are issues longer term - needing the data and not having it is a bit unhelpful as it often needs to be more than a one off snapshot.

[Lysistrata Administrator Community Ambassador in reply to twinkly29]

Yep - mine doesn't drop neatly in the way it 'should' - it likes to sit in mid yellow when I'm not the best.and low yellow when getting worse, but won't necessarily drop below 50% best even when I have other markers of an attack.

However, I do have a bronchodilator response - that's the part that changes for me. It starts with being BIG in response to reliever, but then starts not to last and the response gets smaller and smaller and shorter and shorter. (I have read scientific papers supporting this pattern but it seems not to be well known by clinicians).

However I do get that initial response, which as Twinkly suggests does indicate asthma as a key element - if it didn't change or consistently sat very high I might reconsider whether it's asthma or something else. (My friend who had severe COVID found her peak flows hadn't dropped that much even when she was struggling to breathe with the COVID - not that that's the only alternative, but just as an example).