Documentation
You can stitch yourself up before fortified fights. If you have less HP than your opponent and are damaged, you spend resources to gain some HP.
It's just a temporary measure, however. If the HP aren't beaten out of you by the end of the combat, they fade on their own.
Use
Southside Park (Unlocked by buying 50 or more Omnitech trauma bandages at once from Little Eddie's Back Room)
Start text
In combat:
He stitching his wounds shut as you approach. That… looks painful, but will probably hold for the fight.
Or, if they already have less HP than you:
He is considering stitching his wounds shut as you approach, but seems to decide the better of it.
Inbox text:
You stitched yourself up before combat, healing yourself <X> HP.
Or, if they already have less HP than you:
Effects
Raises your HP for one fight.