This unnamed doctor looked after Dean following a collision with a truck.
This doctor watched over Dean, unaware that Dean had become a detached spirit. When Sam Winchester paid Dean's unconscious body a visit, the doctor told Sam that his father John was awake and he could pay John a visit. When asked about Dean's condition, the doctor informed Sam that Dean's condition was indeed severe, and he did not expect Dean to survive.
He told Sam that Dean was fighting very hard, and there was no guarantee of helping Dean unless he woke up. This infuriated Dean, who was watching the conversation.
Dean eventually recovered due to a deal made by John with Azazel. John died in Dean's stead and the doctor was unable to revive John.