Pressurised systems are utilised in the Uk. Usually for internal staircases. Design is to BS5588 (I think a new reg is out soon something like BS9999??)
The design is highly specialsed and requires a lot of experience. Biggest mistakes are that you need to relieve the air that you pump into the stairwell in some way. This sometimes means that a shaft has to be constructed to let is flow away otherwise pressure equalisation occurs.
Colt Ltd. Uk can provide a design but will possibly charge for it.
Yes, I'd have to agree with the pressure relief aspect - in 90% of the systems that have problems when we look at them (either during construction or during annual performance inspections), we find that insufficient relief is the main source of difficulty.