The account of Jesus being pierced with a lance and producing first water than blood from the wound would be an indication that the wound would be fatal even if he wasn't already dead. The water followed by blood is an indication the wound penetrated a fluid filled lung before piercing either the heart or a major blood vessel the the chest cavity. This is a wound that would be fatal even with prompt modern medical attention.
So one say might if the description of the lance thrust was authentic, then he could not be in any extended coma and was right and truly dead shortly after receiving the wound even if he wasn't before.