>>59Больной isn't really an adjective here. In this case it functions as a noun and an object. It means patient. Just like рабочий - worker, учащийся - student, служащий - officer. The quantity IS specified - one patient. It is actually in accusative case here (the action is directed to the patient). It doesn't have anything to do with that "выпью вина" - pattern. Speaking of which it appears only consumable items can be spoken of like this. It just occurred to me that this pattern uses a kind of ellipsis:
"выпью (немного/некоторое количество) вина". So now it makes sense - "некоторое количество" or "немного" is the actual subject in Accusative and "вина" its the determinant that should be in Genitive.
Back to больной. This word is the same in either Accusative and Genitive cases.
Sometimes these cases are difficult to tell apart. So a simple technique might be of some help. To check a word for Genitive, you ask the following question:
"Нет кого?" for animate things (больного)
"Нет чего?" for inanimate ones (стула)
To check for Accusative:
"Вижу кого?" for animate (больного)
"Вижу что?" for inanimate (стул)
It works OK for native speakers. For foreigners... no idea, at least it's better that nothing at all.