An intensive care unit (ICU), also sometimes known as a critical care unit, or an intensive therapy department, is a special ward that is found in most hospitals. It provides intensive care (treatment and monitoring) for people who are in a critically ill or unstable condition.

People in ICUs need constant medical support to keep their body functioning. They may not be able to breathe on their own and they may have multiple organ failure. Medical equipment takes the place of these functions while the person recovers.

When intensive care is used

There are several circumstances in which a person may be admitted to intensive care. These include after surgery, an accident or a severe illness. ICU beds are a very expensive and limited resource because they provide:

• specialised monitoring equipment
• a high degree of medical expertise
• constant access to highly trained nurses (usually one nurse for each bed)

Some ICUs are attached to areas that treat specific conditions. Others specialise in the care of certain groups of people. For example, an ICU can specialise in:

• nervous disorders
• heart conditions
• babies (neonatal intensive care or NIC), for example, for babies born with serious conditions, such as heart defects, or if there is a complication during the birth
• children (paediatric intensive care, PIC), for children who are under 16 years of age

ICUs can be daunting

Being in an ICU can be a daunting experience, both for the person who is in hospital and for their family and friends. The healthcare professionals who work in ICUs understand this. They are there to help the person who is in intensive care, as well as offering support to their families.

Intensive care units (ICUs) contain a variety of specialised equipment, which may vary from one unit to another. The kind of equipment an ICU has depends on what kind of patients it specialises in treating. For example, a neonatal ICU will have incubators for critically ill babies.

The machines in ICUs make a variety of alarms, bleeps and other sounds. Many of the sounds alert staff about when something needs attention, or if the person’s condition has changed slightly. A few alarms will require immediate attention from the nurse, but most just indicate standard monitoring.

Details about some of the main ICU machines, and what each one does, are outlined below.

Ventilator

If your lungs have failed and you cannot breathe on your own, you will need to be attached to a ventilator. A ventilator is an artificial breathing machine that moves oxygen-enriched air in and out of your lungs.

Being helped to breathe by a ventilator means that you will usually need to be sedated (given medication to make you sleepy) because it would be very uncomfortable otherwise. Ventilators can offer different levels of breathing assistance. For example, if you have difficulty breathing in (inhaling), they can be used solely for this purpose.

If you only need help breathing for a couple of days, it is likely you will have a tube from the ventilator placed in your mouth (endotracheal tube or ETT), and sometimes also in your nose. The tube will usually be held in place behind your neck.

However, if you need help with breathing for more than a few days, you may have a short operation called a tracheostomy. This replaces the tube in your mouth with a shorter tube that is placed directly into your windpipe (trachea). As well as being more comfortable, a tracheostomy will make it easier to keep your lungs clean, and usually requires less sedation.

See the A-Z topic about Tracheostomy for more information about this procedure.

In some cases, your breathing may be assisted with the use of a non-invasive ventilator. This works without the need for invasive breathing tubes and sedation, and reduces the risk of an infection being caused by the ventilator.

During non-invasive ventilation, a mask is securely fitted over either just your mouth, or your mouth and your nose. Air is passed into the mask to help with your breathing.

Monitoring equipment

In order to measure important functions of your body, wires may be attached to various parts of your body by sensor pads, and linked to monitors (small television screens). These help to monitor closely several important functions such as:

• your heart and pulse rate (known as an electrocardiogram, or ECG)
• the air flow to your lungs
• your blood pressure and blood flow
• the pressure in your veins (known as central venous pressure, or CVP)
• the amount of oxygen in your blood
• your body temperature

Monitoring equipment will track every tiny change in your bodily functions, and will alert the intensive care doctors and nurses immediately if any of your functions rise or fall to a level that could be dangerous.

If you have had a head injury or brain surgery you may also have the pressure inside your head monitored. This is known as an intracranial pressure (ICP) reading. In some cases, you may also have the pressure in your abdomen (stomach) monitored. Rising pressure levels can prevent enough blood from getting to your organs and may require further treatment.

IVs and pumps

Tubes that are inserted intravenously (into a vein in your arm, chest, neck or leg) are used to provide your body with a steady supply of essential fluids, vitamins, nutrients and medication, directly into your bloodstream. A tube that is inserted into the main veins in your neck is known as a central line.

These tubes are often called IVs, IV lines or drips. They consist of one or more bags of fluid that hang from a pole (drip stands), and are attached to pumps (syringe drivers), which constantly regulate the supply. You may also be given blood intravenously using an IV.

Medication that is given slowly and continuously by IVs in intensive care can include:

• sedatives: to reduce anxiety and encourage you to sleep
• antibiotics: medication that is usually given in high doses and is used to treat infections that are caused by bacteria
• analgesics: also known as painkillers

In some cases, a small device called a cannula is fitted to the IV line. This allows the flow to be switched on and off like a tap, without having to attach, or re-attach, the line into your vein.

Kidney support

Your kidneys filter waste products from your blood and manage the levels of fluid in your body.

If your kidneys are not working properly, a kidney machine (dialysis machine) can be used to replace this function. During dialysis, your blood is fed through the machine, which removes any waste products, before it is returned to your body.

See the A-Z topic about Dialysis for more information about this procedure.

Feeding tube

If you need help breathing through a ventilator, you will not be able to swallow normally. Instead, a feeding tube can be placed in your nose, through your throat and down into your stomach. This is called a nasogastric tube, or NG tube, and can be used to provide liquid food.

The liquid food contains all the nutrients that you need, in the right amounts, including:

• protein
• carbohydrates
• vitamins and minerals
• fats

If your digestive system is not working, nutritional support can be fed directly into your veins.

Drains

After surgery, tubes called drains may be used to remove any build up of blood or fluid at the site of the wound. These are usually removed after a few days. 

Catheters

Catheters are thin, flexible tubes that can be inserted into your bladder. They allow urine to be passed out of your body without you having to visit the toilet.

You may notice a clear bag hanging from the side of the bed. This bag is called a foley catheter, and it is connected to the tube that goes into your bladder. It is used to measure the amount of fluid (urine) that you produce. This indicates to the doctors and nurses who are treating you how well your kidneys are working.

Suction pumps

Another tube can be passed down inside your endotracheal tube (breathing tube) and attached to a suction pump. Suction pumps are used to remove any excess secretions (fluid) and help to keep your airways clear.

Neonatal intensive care (NIC) equipment

Neonatal intensive care units have specialised equipment to care for babies who are unwell, and those that are born prematurely (before week 37 of pregnancy).

Instead of beds, babies in intensive care are placed in incubators, which are clear, enclosed cots that control the baby's body temperature and protect them from infection. The incubators have hand-sized holes to allow the intensive care doctors and nurses to gain access to your baby.

Babies in intensive care are monitored and treated in much the same way as adults. Your baby's temperature may be monitored using a small sensor on their skin, and the level of oxygen in their blood by a clip attached to their hand or foot.

If your baby is unable to breathe on their own, they will require artificial ventilation through a ventilator. They may also need to be fed intravenously (through a tube directly into a vein).

An intensive care unit (ICU) can often be an overwhelming place, both for the person who is in hospital and for their loved ones. It can, therefore, help to know a little about what to expect.

Medication

When you visit an ICU, many of the people in the ward may appear to be asleep because they are on painkilling medication (analgesics) and medication that can make them drowsy (sedatives). This medication is necessary if the person is unable to breathe on their own because artificial ventilation (when a machine is used to help you breathe) is very uncomfortable without it.

The doctors and nurses who work in intensive care will try to use the least amount of sedatives possible in order to maintain comfort. This means that the people who are being treated in ICUs will be partially awake for some of the time.

Unfamiliar appearances

The people being treated in ICUs are usually connected to intensive care equipment by a number of tubes, wires and cables. You should not be alarmed by this as the equipment is necessary to monitor the person’s condition. See Intensive care - treatment for an explanation of the equipment that is used to treat and monitor people in ICUs.

People who are in ICUs may appear to be slightly swollen. The swelling is caused by the person’s inability to move and the treatment that they are receiving. They may also have visible injuries, such as bruises or wounds. This can be upsetting to see, but the doctors and nurses will always make sure that the person is as comfortable as possible.

Unfamiliar sounds

In an ICU, there will usually be many unfamiliar noises, such as alarms and bleeps from the equipment. These help the nurses to monitor the patients. Most noises are nothing to worry about, but you should not be afraid to ask if you are unsure. The doctors and nurses who work in an ICU are highly skilled, and they will usually be very understanding.

Visiting

Visiting hours in an ICU are often very flexible, but there may be times when you have to wait, for example, if one of the people in the ward requires assistance from the intensive care doctors and nurses. The number of people who are allowed around a bed will usually be limited for the safety of the patient.

In an ICU, the levels of hygiene must always be kept very high, so you will need to use an alcohol hand rub before and after entering the unit. Dispensers are usually found at the entrance of the ICU and by every bed space.

If someone you care about is in an ICU, you may want to touch and comfort them, and this is usually encouraged. It is important to talk to the person you are visiting because they may be able to hear and recognise familiar voices, even if it appears that they cannot. You may want to tell your loved one about your day, or read them a book or newspaper. 

You can bring in things to make the person more comfortable, but you should check with the intensive care doctors and nurses before doing so. Flowers are not usually allowed in an ICU because there is a risk that they could spread infection.

Decisions about treatment

If you are admitted to an ICU, and you are awake and able to communicate your wishes, you have the right to be fully informed and to make decisions about your treatment in partnership with the doctors and nurses who are treating you. They should support your choice of treatment wherever possible.

However, if you are heavily sedated, you may not be able to consent to a particular treatment or procedure. In this case, the intensive care doctors and nurses treating you will decide what is best. They will always explain what they are doing to a person in an ICU, even if it appears that the person cannot hear them.

Wherever possible, planned treatments and procedures will also be discussed with the family of the person who is in an ICU. However, this may not always be possible in an emergency, where treatment is needed immediately.

See the A-Z topic about Consent to treatment for more information about how and when consent is given.

Designated decision makers

Under the Mental Capacity Act (2005), someone who knows that they are going into intensive care may nominate someone to make decisions about planned treatment on their behalf. This person is known as a designated decision maker. If the person in the ICU is unconscious, the designated decision maker has the final say about any planned treatments or procedures.

However, a designated decision maker can only be nominated through:

• a lasting power of attorney: a legal document in which the person who is in hospital has granted someone the power to make decisions on their behalf
• being made a court appointed deputy: someone who is chosen to make decisions on behalf of the person in hospital by the Court of Protection - the legal body that oversees the operation of the Mental Capacity Act (2005)

Therefore, a person who is admitted to an ICU as an emergency measure is not able to nominate a designated decision maker.

See the Direct Gov information on the Mental Capacity Act (2005) for a more detailed explanation.

Advance decisions

If you know that you are going into intensive care, and there are certain treatments that you do not want to have, it is possible to pre-arrange a legally binding advance decision (previously known as an advance directive).

This means that the intensive care doctors and nurses will not be able to perform certain procedures, or treatments, even if you are unconscious. However, these documents must be very specific regarding what you do not want done in order for them to apply.

To make an advance decision, make your wishes clear in writing and have it signed by a witness. You need to include specific details about which treatments you do not want to have, and the specific circumstances in which they may apply.

See the Direct Gov information on Advance decisions for an explanation of how these can be used.