Critical care, also known as intensive care, is a medical specialty that deals with seriously or critically ill patients who have, are at risk of, or are recovering from conditions that may be life-threatening. Critical care involves providing life support, invasive monitoring techniques, resuscitation, and end-of-life care. Patients in critical care units, also called ICUs, are cared for by a team of specially trained healthcare providers that may include physicians, nurses, respiratory therapists, care managers, physical and occupational therapists, and other providers. Critical care treatment takes place in an intensive care unit (ICU) in a hospital, where patients get round-the-clock care by a specially trained team. Critical care is appropriate for hospital patients of every age who are severely ill, and patients may go to the ICU from the Emergency Department or may move there from the general hospital ward if they become critically ill. Examples of patients who need critical care include those who undergo very invasive surgery or who have poor outcomes after surgery, those who are severely injured in an accident, people with serious infections, or people who have trouble breathing on their own and require a ventilator to breathe for them. Critical care medicine encompasses the diagnosis and treatment of a wide variety of clinical problems representing the extreme of human disease.