use the same system for defense. if you really want to stick with cards, you'll have to use more than one deck.... unless you want to split off cards.
say use the non-trumps for the random effects. you'll have to decide when you shuffle drawn cards back into the deck. use the trump cards for status. instead of hitpoints per say, you can have the k, q, j, and joker be the four levels of status, the fifth level being knocked out or dead, depending on how deadly you want to go. you could even set having no status card as knocked out, and taking any more damage auto-kills you.
you might also want to check out "deadlands", it had a fully functional card based system presented in the game.