Okay, so theres a few ways that I've found. Technically there's supposed to be like 8 endings. But I've only found a few.
1. Simply laying low and eavesdropping: if you just eavesdrop for a few days in every room that its possible, you will learn enough about the doctor and then you can simply walk out the front door to leave.
2. Talking/flirting with the guard: (orgy scene) Flirt with the guard multiple times until eventually he will invite you up to stay the night, if you accept there will be a massive orgy scene and then after you will be able to sneak into the bosses room and get information on the doctor, then you leave.
3. Breaking the pipe with the crowbar: after you get the crowbar you can enter the back room in the showers, there will be a bunch of pipes and you can break one. If you are fit enough, and well rested. It will take a few trys to break. Then you escape.
4. Breaking the guards door open with the crowbar: if you go to the 2nd floor and to the 3rd room with "nothing" in it after having the crowbar, there will be a new option to "wait for the guard to go on a smoke break" click it a few times and wait until he does, then rush to the door and use the crowbar on it. It will take about as many tries to break the door as it did for the pipe. Just keep trying. After that there's a few endings once you get upstairs....
5. Good upstairs ending after breaking door with crowbar: once you get upstairs you will have to find a good hiding spot and wait until night, then go into the room at the end of the hallway. You will get the information for the doctor then you can leave.
6. Bad upstairs ending after breaking door with crowbar #1: basically do all the same things in the good ending but jump out the window when almost getting caught, you will wake up in the hospital with a broken body.
7. Bad upstairs ending after breaking door with crowbar #2: basically do all the same things but instead of jumping out of the window, stay and get caught. They will beat you and lock you up in a small room, you are essentially a slave. You will have to listen to your captures and make sure they don't get angry for a few weeks. There's quite a bit of sex scenes in this ending. Eventually you will get rescued by the Institute but only after you are pretty much broken.
8. (I think) (I don't really know if this is one of the main actual endings or not, but I'll include it anyway). Getting rescued by the Institute: draining yourself of everything, and passing out so much then walking outside. You will pass out infront of the Haven and be rescued by someone from the Institute and returned to the hospital with no information on the doctor.