Intensive care medicine or critical care medicine is concerned with providing greater than ordinary medical care and observation to people in a critical or unstable condition.

People requiring intensive care include those after major surgery, with severe head trauma, life-threatening acute illness, respiratory insufficiency, coma, haemodynamic insufficiency, severe fluid imblance or with the failure of one or more of the major organ systems (life-critical systems or others).

It is generally the most expensive, high technology and resource intensive area of medical care. It is offered only to those whose condition is retrievable and who have a good chance of surviving with intensive care aid, the issue is whether treatment will "prolong life or prolong suffering". People are not admitted to ICU to die.

Intensive care usually takes a system by system approach to treatment, rather than the SOAP (subjective, objective, analysis, plan) approach of high dependency care. The nine key systems[1] are each considered on an obervation-intervention-impression basis to produce a daily plan. As well as the key systems Intensive care treatment also raises other issues including psychological health, pressure points, mobilisation and physiotherapy, and secondary infections.

The provision of intensive care is generally administered in a specialized unit of a hospital called the Intensive Care Unit (ICU) or Critical Care Unit (CCU). Many hospitals also have designated intesive care areas for certain specialities of medicine, such as the Coronary Care Unit (CCU) for heart disease, Medical Intesive Care Unit (MICU), Surgical Intensive Care Unit (SICU), Pediatric Intensive Care Unit (ICU), Neuro Intensive Care Unit (NICU), Neonatal Intensive Care Unit (NICU), and other units, as dictated by the needs and available resources of each hospital. The naming is not rigidly standardized. For a time in the early 1960's it was not clear that specialized intensive care units were needed and intensive care resources (see below) were brough to the room of the patient who needed the additional nursing care and resources. It became rapidly evident, though, that a set location where intensive care resources and personel were available provided better care than ad hoc provision of intensive care services spread throughout a hospital.

Common equipment in an intensive care unit (ICU) includes ventilators to assist breathing through an endotracheal tube or a tracheotomy opening; dialysis equipment for renal problems; equipment for the constant monitoring of bodily functions; a web of intravenous lines, feeding tubes, nasogastric tubes, suction pumps, drains and catheters; and a wide array of drugs to treat the main condition(s), induce sedation, reduce pain, and prevent secondary infections.

Physicians that practice in an intensive care unit historically have been the same physicians that care for the patient before transferring to the ICU. This is still commonly the case. In some hospitals there is a special group of physicians that staff the ICU, known as Intensivists, which is becoming an speciality. Whether the intensivist becomes the lead doctor or a consultant on a case is a matter of policy in each hospital. The speciality is unusual among the specialties of medicine in that their backgrounds may be Pulmonary, Anesthesiology, Internal Medicine, or other specialties. The reason for the high representation of Pulmonary and Anesthesiology is the need to be familiar with ventilator management.

[1] The key IC systems are (alphabetically) -- central nervous system, cardiovascular system, endocrine system, gastro-intestinal tract (and nutritional condition), haematology, microbiology (including sepsis status), renal (and metabolic), respiratory system, peripheries (and skin)