Hi Jess,
I just use a peak flow meter -- which only measures the large airways. Even though it isn't the more sophisticated FEV1 meter which I assume you mean is the kind some doctors's offices have, it has helped me a lot.
My doctor gave me the peak flow meter when I first started going to her. I had to measure my peak flow a few times a day, and was shocked at how much it varied because I couldn't always tell that it was so low. Soon, I was able to establish what was my normal and if it fell below a certain number, I had to take extra treatments with a bronchodilator. I started to see patterns too. My doctor saw me once every month and used my chart of my peak flow to try to find the right medications and lifestyle changes to try to get my FEV1 up.
There were times that it was scary low and I had to receive either a cortisone shot (my numbers could go up at least 100 points) or even get an IVP treatment in the doctor's office.
As my asthma became better controlled, my FEV1 started to rise, and I was about to resume more vigorous exercise, I had to hit a certain number before I was allowed to excercise (after using a bronchodilator).
Nowadays, I use my peak flow meter if I'm short of breath or sick, as an indication of how bad off I am. Sometimes, I am surprised by the number, because it doesn't always match the way that I feel. If the number is high and I feel short of breath, I have learned that the small airways may be contricted. I do extra treatments as prescribed and I'm a little more careful about being exposed to bad air. I think knowing your peak flow or FEV1 is important tool.
I see my doctor once a month and have my peak flow checked every time -- and if it stops dropping she changes my medication or something else in my routine.
