The intensive care unit is mainly for patients at risk, because it is equipped with all kinds of emergency equipment and observation equipment so that patients can be rescued and treated at the first time when their lives are in critical condition. If the patient is out of life-threatening condition, he can be transferred from the ICU to the general ward. In addition, intensive care units are generally laminar flow facilities, and the air is relatively clean. At this time, the resistance of weak patients is extremely poor, and they are easily infected with viruses or bacteria in the surrounding air. The staffing of ICU is also more adequate than that of general wards, so it is more timely to treat patients who are resuscitated, receive patients after major surgery, and patients with organ failure or shock.