Deer can survive on one lung. I have seen one. A friend of mine shot a doe that had one lung collapsed and one lung fine. Now, the point has to be made as to how much of the lung is hit. If an arrow centers one lung and not the other, I would tend to think that the hemorage would be enough to kill the animal eventually. However, if one lung is just sliced, and it deflates, the hemorage may not be great enough to cause the animal to bleed out. The only thing I know for sure is that a deer can survive on one lung...I guess I am just trying to add fuel to the fire.