The spell Breath of Life says quite explicitly:
Creatures slain by death effects cannot be saved by breath of life.
But I have some issue regarding what "slain by death effects" means. Let's say a character is on the wrong end of a Wail of the Banshee. It doesn't kill instantly, but has a death descriptor and so is supposedly considered a death effect.
The character fails his save and is reduced to -5 hp. Is he considered "slain"? Would a Breath of Life work?