storing pressure before using "fix NPT"

how can I store the pressure of the system before it becomes zero with “fix npt x 0 0 1 y 0 0 1 z 0 0 50” during the simulation?
there is a “fix store/force” for saving the forces before they become zero with “fix setforce”, but I cant find anything about “fix npt”.

you cannot do that. pressure is a state function of the system. Axel.