Intensive care dates from the polio epidemic in Copenhagen in 1952. Doctors reduced the 90% mortality in patients receiving respiratory support with the cuirass ventilator to 40% by a combination of manual positive pressure ventilation provided through a tracheostomy by medical students and by caring for patients in a specific area of the hospital instead of across different wards. Having an attendant continuously at the bedside improved the quality of care but increased the costs and, in some cases, death was merely delayed. These findings are still relevant to intensive care today, even though it has expanded enormously so that almost every hospital will have some form of intensive care unit. Many questions still remain unanswered regarding the relation between costs and quality of intensive care, the size and location of intensive care units, the number of nursing and medical staff and intensive care beds required, and how to direct scarce resources towards those most likely to benefit.

Patients Intensive care beds are occupied by patients with a wide range of clinical conditions but all have dysfunction or failure of one or more organs, particularly respiratory and cardiovascular systems. Patients usually require intensive monitoring, and most need some form of mechanical or pharmacological support such as mechanical ventilation, renal replacement therapy, or vasoactive drugs. As patients are admitted from every department in the hospital, staff in intensive care need to have a broad range of clinical experience and a holistic approach to patient care. The length of patient stay varies widely. Most patients are discharged within 1-2 days, commonly after postoperative respiratory and cardiovascular support and monitoring. Some patients, however, may require support for several weeks or months. These patients often have multiple organ dysfunction. Overall mortality in intensive care is 20-30%, with a further 10% dying on the ward after discharge from intensive care.