If I was in a burning building I'd make my own Jason shaped fire exit
It is possible to open fire escape hardware using a slim jim or something similar IF the door is badly fitted or the rebate on a pair of doors is bad enough to let a slim jim in (try saying that 3 times fast!).
Even if the bars run top to bottom the panic/crash bar still has to be horizontal for the firebrigade to be happy.
Bypass keys for the firebrigade are available (I had one till it got nicked!)
I have been advised that I can get another one but it'll cost me about £30. I have got one on "order" it is a hinged piece of metal with a number of wards once the key passes the wards it drops down and you then turn it - you hear a loud buzz as the electric strikes all disengage at the same time. Get caught with one without a good reason and you could have a lot of explaining to do.