Here is a interesting on the effect of caffeine and people with asthma. It's actually a positive effect as caffeine is found in this study to have a bronchodialation affect on people with bronchoconstriction. My conclusion, if you have respiratory issues drink tea or coffee on a consistent basis for maintenance it could work. Wonder though if your having an attack if you could down a Mountain Dew quick to get some relief?
Here is the link to the study:
Caffeine helps Asthmatics.