An Intensive Care Unit (ICU) or Critical Care Unit (CCU) is a specialised facility in a hospital that provides intensive care medicine. Many hospitals also have designated intensive care areas for certain specialities of medicine, as dictated by the needs and available resources of each hospital. The naming is not rigidly standardized.

Medicine suggests a relation between ICU volume and quality of care for mechanically ventilated patients. [3] After adjustment for severity of illness, demographic variables, and characteristics of the ICUs (including staffing by intensivists), higher ICU volume was significantly associated with lower ICU and hospital mortality rates. For example, adjusted ICU mortality (for a patient at average predicted risk for ICU death) was 21.2% in hospitals with 87 to 150 mechanically ventilated patients annually, and 14.5% in hospitals with 401 to 617 mechanically ventilated patients annually.