I dont think you killed him. That is the typical high spine, shoulder hit scenario. Start to bleed about 20 yards out, pick up to unbelievable levels, then quit at 300-400 yards. Thats a skeletal hit deer with lots of muscle blood. You did not one lung him. That is a tough scenario to have happen on a broadside. If the arrow went into the chest cavity, the lungs collapse once the pleural barrier was broken, both of them. If either is punctured the blood flow will not stop. It would be a near impossible chance for the deer to have a punctured lung and live. Hemo/Pneumothorax will kill everything, unless acted upon. Air will flow into the chest via the arrow hole and not the deers trachea. Causing tension on the lungs. Hence a tension pneumothorax. Collapsed lungs do not reinflate without help, and pneumothorax do not just go away. There is more than a probable chance this deers shoulder stopped the broadhead and the arrow did not cause a fatal hit.
Now I will give you this, my medical training is in humans with penetrating trauma. My Paramedical degree is only in humans and not cervid medicine. But we are both mammals with extremely similar cardio/pulmonary systems.
Again, I dont think you killed the deer.