Gryan, do you have a picture of the rib cage? It looks to me like that scar is too high to be through the chest cavity??? Hard to tell with out seeing it in person.. and I'm not saying you're wrong. It just looks too high in that picture.

Anyhow, back to the question. In my opinion.. (and I have a pretty good handle on physiology)... There simply is no 'void' below the spine. In fact, if you shoot right under the spine, you'll hit the dorsal aorta.. which will drop a deer in seconds.

I do believe that one lunged deer do sometimes live. (deer have great physiologic compensation mechanisms) Also, I've believe that some double lunged deer can travel great distances if the arrow hits them just so. A double lunged deer usually drops quickly because of massive blood loss, not because it suffocates like a lot of people think.. If, for some reason, the part of the lungs hit are not very vascular .. and.. the arrow hole does not cause a double pneumothorax (collapse of both lungs) then the deer is going to go a long ways. Could it live? Nothing is impossible.

Still, just because it goes a long ways.. or even survives.. does not mean there's a void. There is no empty space inside a deer.