At sea level, when I was younger and more foolish, I found I could blow into a sphygmomanometer and make it go up to 200mm Hg. I ended up giving myself surgical emphysaema - somewhere near my ear, the Eustacian tubes burst and the skin near my ear began to feel like bubble wrap making little crackly noises if you massaged it.
200mmHg is 3.9 psi above atmospheric, so I can imagine that at high altitude it may buy you a little more conscious time with which to make an emergency descent. It's not a pleasant thing to do and I can't comment on other aspects such as whether it would work at high altitude, and whether it would be a good idea to breathe out whilst descending.