The intensive care unit (ICU) can be defined as an area reserved for patients with potential or established organ failure and has the facilities for the diagnosis, prevention, and treatment of multi-organ failure. Usually, the ICU is located in close proximity to A & E, the radiology department, and the operating theatres, as it is between these areas that patient flows are greatest. In large urban hospitals, there may be more than one ICU, some of which serve specific patient populations, such as paediatrics, neurosurgery, cardiothoracic surgery, liver failure, and burns. Many hospitals also have high-dependency units (HDUs) that offer higher nurse-to-patient ratios and more advanced monitoring than a general wards does, as well as limited organ support. In the UK, the distinctions between ICU, HDU, and general ward have been abandoned in favour of a classification based on the patient’s needs rather than their location.