To buy a medic kit without need to use it now but can use it later or even drop it when die or let it drop. no idea if its possible to have it in equipment like number 5 or have it on a special button to use it. maybe with a display to see how many kits you have and can use.
another thing would be to buy medic speciality so you can heal other teammates with it (50 - 75 HP) and for own purpose it gains (33 - 50 HP) maybe with cvars how many you get for it and how much it costs to have that ability.
30 ammo packs and then you have it for 10 rounds after 10 rounds you need to buy medic again, when beeing medic you have a glow or another sign for beeing medic. medic class should have 20% hp more then normal human.