If you get injured, you are placed in the hospital. Even though you instantly recover, the hospital nurse will insist keeping you for observation, even if the Ants are about to overwhelm Lizard Breath.
You start at a bed on the second floor. Wait for the nurse to leave, and get out of bed. When you are walking the halls of the hospital, you will need to avoid any doctors and nurses by hiding in nearby rooms or beds. The doctors will capture you if they either make contact with you, or reach a room's entrance when you aren't hiding in a bed.
YOu need to reach the stairs or elevator in the middle of the hospital.
Once you reach the first floor, you need to exit at the bottom. However, there are two guards that are standing right next to the door. You can draw them away by circling around the first floor, then taking the exit, or by running out on a wheelchair. Approaching the doors on the first attempt will not work.