Not quite correct. ICU is not for "observation." There are specific criteria that a patient needs to meet to be transferred to a critical care unit. We don't take patients for "observation."
Also, your staffing comment is incorrect. Hospital staffing is tied to EVERY department. The medical floors do not have staff specially assigned for whatever an ICU call is. I think what you are referring to is whats called an RRT (Rapid Response Team). Hospitals due staff a crisis RN 24/7 typically to respond to RRT's. RRT's typically consist of an ICU Dr that is taking the calls from that shift, an RT, and the crisis RN. Depending on the hospital size, depends on how many crisis RN's are on staff.