Critical care: what intensive care covers, who is treated and what families can expect

Critical care is a hospital service rather than a single organ specialty. Intensive care units are described by the NHS as specialist wards that provide treatment and monitoring for very ill people. They are staffed by specially trained professionals and contain sophisticated monitoring equipment.

The Intensive Care Society says admission is reserved for seriously ill patients who need invasive treatments to save their lives, and that the team is multi-professional: doctors, nurses, psychologists, physiotherapists, speech and language therapists, dietitians, pharmacists and occupational therapists all take part. The lead doctors are consultants who have specialised in intensive care medicine.

Many hospitals also have a high dependency unit (HDU) for people who need closer observation than a ward can give but not full organ support. The boundaries between levels of care differ between hospitals, so ask which level your relative is on.

The NHS says that most people in an ICU have problems with one or more organs and gives common examples: a serious accident such as a road collision, severe head injury or burns; a serious short-term condition such as a heart attack or stroke; a serious infection such as sepsis or severe pneumonia; and major surgery, either as a planned part of recovery or as an emergency measure when complications arise.

In practice, the clinical groups behind those headings include breathing failure needing a ventilator, circulatory failure with very low blood pressure, kidney failure needing filtration, severe brain injury, and the aftermath of cardiac arrest. Our condition guides to sepsis, acute respiratory distress syndrome, mechanical ventilation and delirium in intensive care cover the individual problems in more depth.

The NHS describes a ventilator that helps breathing through a tube in the mouth, nose or a small cut in the throat (tracheostomy), monitors for heart rate, blood pressure and oxygen, intravenous lines and pumps for fluids, nutrition and medicines, feeding tubes, and drains and urinary catheters. Painkillers and sedatives are common because some equipment is uncomfortable.

The Intensive Care Society says an ICU is louder than an ordinary ward, partly because alarms sound frequently to keep patients safe, and that an alarm does not necessarily mean something is wrong. It also notes that the first few hours are often unstable and the condition can change often.

The NHS says visiting hours are usually flexible, though there may be times when visiting is not advised, and the number of people at the bedside may be limited. Visitors are asked to clean their hands on entering and leaving, and should avoid visiting if unwell. Patients may be drowsy, confused, swollen or bruised, which can be upsetting; staff will explain the equipment if you ask. You are usually free to touch and talk to the patient, and familiar voices may help even if there is no obvious response.

If the patient is awake and able to communicate, the NHS says they are fully involved in decisions. If they are unconscious or sedated, treatment follows any decision-maker they nominated or any advance decision they made. Where neither exists, the team will usually decide what is in the person's best interests, discussing it with relatives when possible. Families should feel able to ask for a regular named contact on the team and for updates at predictable times.

The NHS says that some people leave the ICU after a few days, others stay for months, and many make a good recovery. Lingering problems can include weakness and stiffness, extreme tiredness, loss of appetite and weight, sleep problems, depression, anxiety or post-traumatic stress, and difficulty thinking clearly or remembering. It says these can last several months and that some people need rehabilitation.

The Intensive Care Society adds that muscle and weight loss and joint stiffness improve as people become more active, and that vivid, unreal memories, hallucinations or nightmares are common during the stay and very rarely continue after recovery. ICUsteps, a patient support charity, produces a guide for patients and relatives that covers recovery at home. Ask the hospital whether it runs a follow-up clinic for people who have been in critical care.

Critical care is almost always provided on the basis of clinical need, and emergencies are managed in the nearest suitable hospital whatever the funding route. Planned private operations that carry a higher risk of needing post-operative intensive care are usually done in hospitals with an on-site critical care or high dependency unit, or with a transfer arrangement.

If you are having major private surgery, ask in advance where you would be looked after if you needed intensive care, whether that unit is on the same site, who the on-call intensivist would be, and whether your insurer or the hospital would cover an unplanned admission or transfer. These are questions about arrangements, not predictions of what will happen. Facilities change, so confirm details with the hospital.

Critical care starts with recognising that someone is seriously ill. The NHS tells people to call 999 or go to A&E if they think a person might have sepsis, and lists signs such as confusion or slurred speech, uncontrollable shivering, muscle pain, difficulty breathing, mottled or pale skin, and passing very little urine. It tells people to trust their instincts if they think something is seriously wrong.