my asthma nurse explained this to me as th efirst puff opens up your airways for the second puff to go down farther and do the job. does that make sense the first is a primer adn the second is the worker
i agree with the above poster the palpatiosn and jittery feelings go away after a tiem usignthe inhalers i think th ebody gets used to it
best of luck and odnt worry abotu holdign your breath if you cant

I have same issue soemtimes and the inhalers work just fien as long as i space the does as th esbove said though i use any where form one minute to fiv emnut3es then y secodn does as per my nurse
MK