Well, there are lies, damned lies... and statistics.

I would question whether the "low success rate" for CPR is mostly due to its ineffectiveness of helping people that CAN be saved or if it is used very often on people who are already good and dead.

As OBG said, if the brain is guacamole, or he's bled out, or its been too long, NOTHING is going to be effective. That doesn't mean you shouldn't try.