Normally there’s no real grey area when it comes to the distinction between living and dying in D&D. If you’ve got 1 or more hit points you’re living. If your hit points are between 0 and your negative bloodied value you’re dying. As long as you’re living then you can act on your turn whether you’ve got 1 hit point or 100 hit points. But when you reach 0 hit points or lower you fall down and start bleeding out.
In some cases taking excessive damage may kill you, dead-dead outright, but most of the time you’ve got a fighting chance of waking up. If you’ve got a leader in the party or an ally with a decent score in Heal, then you’ll likely be back in the action by the time your next turn comes around. Most of the time falling unconscious isn’t even a big concern. After all, the way that 4e is designed makes it practically impossible for PCs to die.
However, there will be those rare occasions when the leader can’t help you and the other PCs are in so much trouble that they can’t take the actions necessary to use their Heal skill on you. These are the rounds when all you can do is roll that death save and hope that you get a 20. Being in this situation sucks! What’s even worse is if you spend multiple rounds in a row making death saves and not getting that elusive 20. I’ve played in a few games where the rest of the PCs can’t or won’t help their wounded comrade and that player does nothing but make death save on their turn. This is not fun.
After this happened in a recent encounter where a player was sidelined for over an hour we decided to introduce a new house rule that would minimize this kind of player exclusion from happening again. The proposal was to create a new state somewhere between living and dying.