Odd PEF readings

Hi - new here and I have a query about some recent PEF readings.

So I was only diagnosed with asthma in October, and it’s been relatively uncontrolled since then so I’m still trying to find my true personal best. It goes up with every new medication I’m given, which is great. I’m a 5ft tall woman and I just hit 590 after being on montelukast for two and a half weeks (did it twice to be sure!).

I’m not looking a gift horse in the mouth, but that’s about 200 over the estimate for a woman my age.

Is this normal? What factors impact someone having an unusually high PEF personal best?

Side note: this is also retrospectively frightening as it means my first attack in December took my lung function down even farther than initially thought (to roughly 17%).

[EmmaF91 Community Ambassador]

Hi

PF best has a lot of factors which can affect it... if you were very sporty as a child, or are so now, if you sing or play a wind instrument etc, if you have a naturally larger lung field and even things like learning the correct technique you will usually have a higher best. If you smoke, are very obese, have a naturally smaller lung field etc you will usually have a lower best. The predicted is sort of the average expected for your age and height.

My best is 630 my predicted is 440. I used to be very sporty before my lungs kicked off big time. The main issue with very high personal bests is when people compare your scores to your predicted. As you found out now your first attack was actually 17% rather than whatever % they said you were, so getting appropriate treatment can be more difficult unfortunately. Hopefully you have an asthma action plan as this can help you explain the situation to medics when you’re needing emergency treatment and it also gives you the boundaries of when to seek help.

Hope this explains this a bit

[Lysistrata Administrator Community Ambassador]

Hi, Emma has said most of it but just wanted to add that I'm another one with a much higher personal best than expected. Predicted is 450-470, actual best is 630 like Emma. In my case I played the oboe for about 10 years and have also sung regularly from about age 6. I can have a 'good' peak flow, take reliever and get 20% of reversibility going up to my best (improvement of about 15% after reliever is usually used to diagnose asthma).

I also have issues with them thinking I'm fine because I am around my predicted (plus my peak flow doesn't actually drop neatly either - I can have a bad attack and still be over 50% of my best which is unhelpful!) I usually state that my best is much higher than predicted and they often listen to.some degree, but it hasn't stopped some drs refusing to believe it (one nurse told me only men could have that peak flow...right and I'm taller than the average woman at 5 ft 8 so that's also impossible, because all women have to be the average height and only men can be 5 ft 8?! I feel like they don't quite understand what a population average is...)

If you have any spirometry tests done you will probably do much better than predicted in those too especially if you're having a good day - worth bearing in mind especially to use as a comparison for any future tests.

[Hidden]

It’s so good to know it’s not just me! I was very sporty as a child, and even now I still walk about 5 miles a day. I also used to play the cornet and the trumpet when I was younger. I guess these things have helped me more than I thought.

You’re both right though. Dr’s have seriously underestimated my asthma because of this. I have too. One A&E Dr told me I was fine to go home without steroids since my PEF was 300...after 2 nebulisers. For a normal woman my height that’s about 75%, but for me barely scrapes 50%. I was in the low amber zone for weeks after that.

I had a spirometry done a short while after this all started. At that time my reading without meds was 238. I forget what the other outputs were. I know I improved drastically after Ventolin and my nurse had a right go at the Dr (who’d told me no meds for 24hrs beforehand).

I suppose it’s just good to hear that there are others like me out there. It really helps me to put all of this in perspective. Thanks so much guys.

[Poobah]

Keep a record of your PEF so that you can demonstrate a decline in capacity if necessary when seeking emergency treatment. Doctors will look at the charts and assume you're OK but showing a pattern of your normal PEF will help them decide on treatment.

Some asthma plans will have a space to record you personal best and what action to take at certain decline points. This should be a good record to carry for emergency treatment situations. Hopefully you'll never need it.

[hilary39]

My peak flow is higher than average too in spite of my having severe and often incapacitating asthma.

I feel like I broken record because I say this in so many comments on this site but I'll repeat myself again here in case it's a concept you aren't familiar with

For many of us, severe asthma manifests in the small airways so, for example, you could be pretty miserable and struggling to breathe, but have "normal" readings on the devices that measure the big airways--peak flow and FEV1 on in spirometry results. Controller inhalers do a good job of keepring large airways open but the medicine can't always reach the small aiways because they are too tiny. The only measurement that gets at how well the small airways are working is the FEV25-75 spirometry measurement.

A lot of doctors will tell you there are too many variables affecting FEV25-75 to make it ideal for definitiely classifying obstruction in the small airways but it's at least a good way to get a sense of what's going on. For example, my FEV1 (big airways) is sometimes 120% of predicted but my FEV25-75 is in the 50-60% range.

[Hamscoul]

My peak flow at a recent asthma appointment was 680. I have severe eosinophilic asthma and I am being started on a biogic tomorrow. No matter how bad my asthma gets my peak flow never gets very low. Last severe bout my peak flow was 470 so it was low for me.

I now have a written down asthma plan. I have always thought peak flows readings were a bit pointless because my symptoms were always worse that my peak flow suggested. Now I have seen my plan written down, peak flow readings make much more sense. That said mine are all over the place but I am learning what is normal for me.

[Blue-Breeze]

My normal is 400. I downloaded an app some time ago which I'm so pleased I did. At the GP on Friday last week I was able to show him the various levels and the increase in PF after reliever. After listening to my chest I had generally poor air in take and was given a course of pred, with next step instructions. This app has proved it's worth a few times now.