Unmissable Story achievement. Can be done on any difficulty.
This guide shows how to activate all the vents better than I could show you. Credit to HMRoyalMachine.
To rescue the Female doctor, hurry a little and use detective mode. Place explosive gel on the wall in the front. Then creep around to the left, and place explosive gel there, too.
The other doctor is just a fight with about ten unarmed goons. Pretty easy.