Hmm, I always pictured Breathtaker's effects being closer to the bronchoconstriction caused by Anaphylaxis.
Reading up on the Toxic spirit power called Anaphylaxis though, it's not even a little similar, game-wise.
QUOTE
Anaphylactic Shock: If the damage is not completely resisted,
the victim enters anaphylactic shock, resulting in muscle
spasms and systemic failure resulting in death if untreated. The
victim takes 1 box of damage each Combat Turn until he dies
from cardiovascular breakdown, unless he is treated by a First
Aid + Logic (2) Test with appropriate drugs (i.e. a medkit), or
an Antidote, Detox, or Heal spell.
Wow, what does that even mean? It doesn't say that the damage is unresisted, so...
Anyway, true anaphylaxis lasts hours to days if left untreated.
But, yeah, Breathtaker is a mega-nasty almost illegal bio-chemical crowd control gas. If you're a totalitarian state looking to put down a marching mob of orks and trolls, you're going to want to see them go down and stay down for more than 10 minutes. Thirty minutes for the standard "heal this stun" rush-rest-test seems fine to me... If you let dudes rush the job on recovery... which isn't disallowed by RAW.. Anyway, ye olde average Ork would be back on his feet, but still hurting after 30 minutes without treatment. That's almost too quick if you're a squad of jackboots trying to cart off 50 angry metas.