Other way is just to make the revive give 60hp to whatever the current status of health of the player is. If player is fully dead, then after the revive health will be 60. If player has even 55hp then syringe adds still 60hp but as the overall healt is capped to a certain number, then even using syringe on 95hp player would not give some extra health boost. Then medpacks would not be so much used to revive at scene but to be dropped down to some key parts where someone can find them and get health back (for example in goldrush medic could drop some packs as allied to bridge area and move on).
Currently the revive train as youcan revive 10 people in a row faster than 10 seconds is bit absurd and something could be maybe capped there (syringe speed, amount of health..?).