Why would you limit it to having actions? You are much more likely to die from a fireball if you are unconscious so aren't you spiraling towards death? If you have penalties and you lie down and play dead, is the spiral over?
I'm not limiting it. I'm merely saying what the term has historically meant. Consider one of the original images:
You are (Snoopy?) in a WWI fighter plane. It's made out of wood, fabric, and bits of metal, but a good chunk of its cross section is only air or other things that aren't absolutely critical to keeping you aloft right this moment. You get into a tussle with the Red Baron. You burn some ammo, take a few minor knicks in the body of the plane, bloody your hand pulling it out of the way--but no spiral yet. You aren't 100%, but you can fight like you are. No death spiral has yet begun.
Then you take a nasty hit on one of the wings. You start to lose altitude. You can't evade to the right very well. The Baron comes in for another pass. You outsmart him with a barrel roll and quick loop, take a shot, but that wing makes you shake and you miss. Next time he comes around, he nails you again. The plan starts
spiraling down, not completely under your control. Fortunatley for you, one of your buddies engages the Baron. So at least you have a chance.
As you continue to spiral down in this classic "death spiral" things get worse the longer it goes. The structure starts to shake. You lose pieces. This makes it even harder to get control. You spin around and around, and finally crash into the ground. You plane is burning, and the "death spiral" is now over.
"Aha," you say, it only ends when you are dead, but you were effectively dead when you went into it. That was true for awhile. Then a desperate Allied aviator found out the trick (having nothing better to do in the few seconds he otherwise had left)--deliberately go into a dive to escape the spiral, and then pull out. Just make sure you start while you still have room to pull out and structure left to handle it.

That is, you can still act, but your options are increasingly limited. All the guys that didn't figure this out before tried things too. They simply didn't work.
As long as you still have options (i.e. can act) but are getting more limited and less effective as the spiral continues, you are in a death spiral. When you no longer have options, the spiral is over. That doesn't mean the options have to be good ones.
