What accounts for changes in peak expiratory flow readings? - Asthma Message Board

kellysmum · 12-23-2007, 09:00 AM

Me again-another question.

My peak expiratory flow readings are all over the place. Before I started on Duoneb, I was only blowing around 320-350. Now, when I get up in the mornings, I can usualy blow about 390 (I even blew a 430 yesterday afternoon around 3:00, and I was so happy!) Now, this morning, even after using my meds, I'm only blowing a 350. Does anyone know what accounts for these changes, why it would be 390 a couple of hours ago and down to 350 now? Or am I just blowing in this thing way too much and that's my problem?

Thanks.

gcsjr · 12-23-2007, 02:37 PM

Peak flow readings tend to vary throughout the day. Usually they're lower in the morning and are higher later in the day based on your body's natural changes. Readings tend to peak in late afternoon/early evening. If you're checking your peak flow readings more than a couple of times a day (and aren't doing it in response to specific symptoms) you're probably overdoing it.

I don't know if the doctor told you this but usually readings from 80% to 100% of your "normal" reading are considered to be in the "green zone" or O.K. - 50% - 80% is considered "yellow" or cause for some concern and less than 50% of normal is medically serious.

If 390 is "normal" for you, anything about 312 would be in the Green zone and means your asthma is pretty well under control.

kellysmum · 12-23-2007, 02:51 PM

Thanks for the reply. I was so happy; I managed a 450 this afternoon. I notice my readings are higher after I've been out of the house and active for a little while. I don't know if that means that something in the house is bothering my asthma, or if it's just because the activity I'm engaging in outside of the house makes me relax more or makes my the smooth muscle in my lungs contract more or what. But it's nice to know these mid-afternoon peaks in my flow are normal.

Thanks again.