Critical care nursing is the nursing of people undergoing life-threatening physiological crises. According to the American Association of Critical Care Nurses (AACN), "the scope of critical care nursing is defined by the dynamic interaction of the critically ill patient, the critical care nurse and the critical care environment" ( American Association of Critical Care Nurses, 1984). Critical care nursing may be distinguished from nursing practice in general by the severity of the patient's illness, the particular skills of the nurse, and the setting where the nursing is practiced. Joan Lynaugh and Julie Fairman distinguish two criteria inherent in the meaning of critical care. "First, the person receiving care is physiologically unstable and at risk of dying. Second, intensive care is usually given in the expectation or hope, however slim, of the person's survival. The relationship between them [these criteria] changes over time" ( Lynaugh and Fairman, 1992: 20).
Critical care units emerged in American hospitals after World War II. Medical specialization, increasingly sophisticated medical technology, and advances in anesthesia, cardiology, and surgery influenced this phenomenon. Nathan Simon attributes the development of the modern intensive care unit (ICU) concept to three major forces. First, the recovery room experience in the 1940s and 1950s demonstrated to medicine and nursing the effectiveness of continuous nursing surveillance of very ill patients. Patients waking up after anesthesia and surgery could be monitored in one large room for immediate complications such as respiratory distress, cardiac or blood pressure abnormalities, or bleeding. Second, hospital planners proposed a progressive patient care concept: patients in hospitals would be grouped according to the amount and intensity of nursing care required. Their goal was efficiency -- the best matching of nurses with patients. Third, complex technology, medical specialization, and new surgical procedures required more sophisticated postoperative nursing care ( Simon, 1980: 2-3). The development in the early 1960s of cardiopulmonary resuscitation (CPR) machines for monitoring heart rhythm (cardiac monitors) and DC (direct current) defibrillation for the treatment of lethal