Modern intensive care originated during the poliomyelitis epidemics of the 1950s, when tracheal intubation and positive pressure ventilation were applied to polio victims, resulting in a substantial improvement in survival. Patients were managed in a specific part of the hospital and received one-to-one nursing care, features that still largely define intensive care units (ICUs) to this day. From these beginnings, there was a gradual development until the ICU was a recognizable component of most general hospitals.

In the early days of intensive care, patients were often young and previously fit, with only single organ failure. If they survived, a full functional recovery could be anticipated. Today, in keeping with the changing structure of society, patients are often elderly and many have complex pre-existing medical problems, which predispose them to develop multiple organ failure during critical illness. As a consequence, the prospects for survival from critical illness are sometimes limited. This, together with the realization of the large costs involved in providing intensive care, typically approaching £2000 per day, has led to debate about how intensive care should be provided in the future. In particular, there is increasing focus on the complex ethical issues that surround admission, provision and discontinuation of intensive care therapy.

Nevertheless, intensive care medicine has become an established and fundamental part of modern health care. Critical illness may arise from a variety of disease processes, but the pathophysiological changes that result lead to common patterns of organ dysfunction. By recognizing these patterns and understanding the interactions between different organ systems, intensive care teams can improve the outcome of critically ill patients. The role of intensive care includes:

Resuscitation and stabilization

Physiological optimization of patients to prevent organ failure

Facilitation of complex surgery

Support of failing organ systems

Recognition of futility.

Traditional definitions of ICUs and high dependency units (HDUs) attempt to separate the functions of each.

Critically ill patients can be classified according to the level of medical and nursing care required (see Intensive Care Society 2002 Levels of Critical Care for Adult Patients www.ics.ac.uk/icmprof/downloads/icsstandards-levelsofca.pdf) (Table 1.1).

TABLE 1.1 Levels of critical care

Specialist care is recorded by attaching one of the following letters as a suffix.

N – neurosurgical, C – cardiac, T – thoracic, B – burns, S – spinal injury, R – renal, L – liver, A – other specialist care.

Patients should be nursed in an area capable of providing the appropriate level of care. While level 2 care may be provided in an HDU or ICU, true level 3 care can only be provided in a suitably equipped ICU. In reality, these levels of care are not discrete entities, but represent points on a continuum or spectrum. As their condition changes, patients may need a greater or lesser level of care, and frequently move between the defined levels.

As the level of care required by an individual patient can change rapidly, it is important that those at risk of deterioration and needing increased levels of care are identified early, so that the appropriate interventions can be instituted.

A number of scoring systems have been developed to help staff detect those patients who are at risk. These are based on the principle that patients develop abnormal physiological parameters as their condition starts to deteriorate. The scoring system can be used by any member of the ward medical or nursing staff and if appropriate, the intensive care outreach team can be called (see below). An example of a typical early warning scoring system is shown in Table 1.2. The response triggered by the scoring system is shown in Table 1.3.

TABLE 1.3 Typical response to early warning scoring system

Outreach is a relatively new concept in critical care. Traditionally, intensive care staff have tended to stay in the ICU and await the referral of patients from other areas by the attending medical staff. It is increasingly recognized, however, that the ICU staff have much to offer critically ill and potentially critically ill patients outside the ICU. This has led to the development of critical care outreach teams.

These teams commonly consist of senior members of medical, nursing and physiotherapy staff from the ICU who provide a liaison service and an immediate point of contact between the ICU and other areas of the hospital. Their roles include:

Identification of patients at risk

Prevention of further deterioration and the need for subsequent ICU admission

Support for level 1 care on the wards

Education and the promotion of critical care skills

Identification of patients unlikely to benefit from ICU admission

Facilitation of discharges from higher levels of care back to the ward.

Once contacted, the outreach team will usually assess a patient and may offer advice and support to ward staff. Early advice on matters such as fluid management and provision of intermediate respiratory support (e.g. physiotherapy / high flow oxygen / CPAP) may prevent further deterioration and enable the care of the patient to continue at ward level (level 1 care). Alternatively, the team may institute more advanced therapy and expedite transfer to an area capable of providing a higher level of care (level 2 or 3).