The critical care unit has become an integral and essential part of a modern acute hospital, providing an environment for the observation and treatment of the severely ill patient. Many large hospitals are able to support separate medical, surgical, neurosurgical, and respiratory units, while in small institutions, a single multidisciplinary unit serves the needs of several specialties.

Critical care demands many clinical skills that are not always obtained during the course of basic medical or surgical training. Specific training, is therefore, widely acknowledged to be essential for those embarking on a career in critical care, regardless of their primary specialty. The critical care clinician must be able to sustain the physiological equilibrium of the patient by pharmacological and mechanical means. This requires constant surveillance of the patient, anticipation of adverse events and aggressive intervention when necessary (proactive management). Meticulous attention to detail of each organ system is essential and yet the patient must always be considered as a physical and psychological whole. Time is of the essence; when intervention is planned, it should be undertaken quickly and without delay.

A major component of critical care is counselling and support for the relatives and friends of the patient. Time must be set aside to explain the reasons for, and the consequences of, investigations and therapy. This responsibility cannot be delegated to the junior surgical or nursing staff but should be undertaken by the most senior member of the surgical team. Not only is this an essential part of the surgeon's responsibility to the patient, but it also minimizes errors in communication and the risk of litigation.

As with other aspects of health care delivery, the nurse fulfils the key role in the provision of critical care. The intense and unremitting nature of critical care practice places severe burdens upon nurses, and the clinician must provide a team approach to support nursing staff. A ‘one to one’ nurse to patient ratio is highly desirable and is probably the most important factor in ensuring quality of care.

The following chapter deals with several critical care topics, classified according to the major organ systems.