If you have to defend yourself should you give medical aid to the person that just tried to hurt you? 

No.  Is the simple easy answer and should be the end of it.

Three things to consider when making this decision: 

The Tactical Situation; will this act put you further in danger?  Morally; is it the right thing to do?  Legally; will this make your actions more or less defendable in court? 

See the entire discussion on https://modernselfprotection.com