He couldn't pass out. 

As much as he wanted to, as light-headed as he felt, his adrenaline kept him 
going, keeping his just alert enough to make sure she didn't take a second shot 
at him. She'd have a much easier change trying to kill him if she attempted to 
try it now. His muscles ached, his head was swimming, and he could barely draw a 
breath. 

And still, he was awake. Hell, it was a miracle he was even alive. She'd had a 
clear shot for his neck, and almost connected with it. Only a moment's warning 
saved him from a rather bitter end. 

He wanted to sleep so badly, but his body simply wouldn't let him do that. 

Inwardly, he hoped that someone would chance upon him in this cavern... and 
cursed himself for not telling Bella about where he'd gone off to. 

"She'll find me... I'm sure of it..." His words were mere blood-speckled wheezes. 
"I'm... sure of it..." His eyes tried to close, only to snap open a moment later. 

He couldn't pass out. And quite frankly, he was thankful for the fact.