peak flow?

[WoodSheddin]

flow rate does not correlate ot capacity. if you want to measure capacity you could use this http://www.windsongpress.com/breathing% ... oldyne.htm

another aid which does not give precise measurements but gives rougher feedback measurements is a breathing bag. I use a 6 liter bag which I know I can fill just full on my fullest breath and most thorough exhale. this works well to double check I am replenishing properly or inhaling deeply enough in general. it is easy to get lazy and only take 60% breaths.