Possible one lung hit? Any advice?

[WestNDMuleys]

Hello, my friend shot a mule deer buck shortly before dark last night. He said it went about 100 yards and bedded down. He didn't want to get it out of its bed in case it was gut shot. He went to his bed this morning and there was a lot of blood with some bubbles as though at least one lung was hit. But the buck had kept moving at some point and he didn't have any luck finding it. Any advice or experience with one lung hits and or bubbles in the blood in its bed?

 

[WestNDMuleys]

With his bow. He looked today with no luck and I believe blood trail ran out. Was thinking tomorrow we would go gridsearch the thick cover surrounding the area.

 

[DW]

They usually head to water. If he cut lung or liver, he's dead. Good luck.