For what it's worth, here's the game text you get when you learn the skill:
After the combat, you patch yourself up, healing 1 hit point.
Your practice with the Trauma Reference has given you some excellent insights into first aid as a whole.
You've learned a new Skill: Trauma Tech
I had the trauma reference equipped and no other first aid items or effects. Maybe you have to heal a certain number of HP with the reference equipped, but I suspect it's just a random roll each time you heal with it equipped.