Intensive Care Unit (ICU) delirium – also known as acute confusional state – is an extreme form of anxiety that occurs when someone is in critical care.

It can take the form of hallucinations or delusions, and leave someone feeling confused and frightened, or unable to think or speak clearly. The experiences leave some struggling with anxiety or depression long after being discharged.

Delirium affects up to 80 per cent of patients in intensive care, but lack of understanding, fear of judgement or even shame can stop people seeking help.

Prevention, recognition and education is vital – and so is speaking up if you are struggling with your own experiences. Together, we need to challenge the stigma.

ICU delirium is very common, but that doesn’t mean it’s normal, and we need to talk about it more.

Katarzyna Zamoscik

Katarzyna (Kate) Zamoscik is a Senior Staff Nurse in Critical Care at Royal Papworth Hospital, the only hospital in the UK that performs pulmonary endarterectomy surgery for people with chronic thromboembolic pulmonary hypertension (CTEPH). She is also an ICU delirium ‘champion’, with many years behind her of caring for people with these experiences.

“Every year, 170,000 patients are admitted to intensive care in the UK and a large number of these patients are likely to experience ICU delirium. This also means that there is a lot of relatives are affected by it too.

ICU delirium is very common and it’s really important that we encourage understanding of it. We don’t want patients leaving intensive care feeling traumatised or feeling unable to return to normal life because of psychological distress.

Defining ICU delirium

Patients may not remember why they are in hospital, and they may be hyper-alert and very observant of what it happening around them (so they will become ‘over-stimulated’) or they can be the opposite – too drowsy to be aware of what’s going on around them.

They can be easily distracted, so will have difficulty taking in information or understanding what is being said. They may be forgetful and feel disorientated. They may have difficulty making judgements, have incoherent speech (rambling), or be unable to recognise spaces or shapes.

Some patients may hallucinate or have delusions. The deterioration of mental faculties might affect their understanding of their surroundings and situation, which can make it very frightening for them. 

Some patients are very hyperactive – agitated and restless – with severe anxiety or mood swings. They can be very fearful and think that something bad is happening to them. This type of hyperactive delirium is actually quite dangerous, because patients might pull the tubes out and put themselves at risk of harm.

The opposite type of behaviour, which is much more common in delirium, is known as ‘hypoactive’ delirium. Patients are lethargic, very quiet and unusually sleepy.

The most common presentation in critical care is when patients move between the two states – from agitated, hyperactive behaviour to becoming sleepy and unresponsive. 

Delirium often comes and goes and fluctuates throughout the day.

Most cases of delirium resolve within days, but some do persist for weeks or months. It does depend on the individual and the disease burden.

Risk factors for ICU delirium 

There are certain risk factors for delirium. It can be a consequence of low oxygen level, of infections, kidney or liver disease, or even a sign of withdrawing from substances – for example if someone is used to smoking, but has been in hospital for a long time.

It could be a side effect of taking certain drugs, or immobility, constipation, dehydration, or sleep deprivation – or simply the experience of being in hospital. Usually, patients have multiple drivers for their delirium rather than just one thing. There can be so many reasons.

From research, we know that certain groups of patients are more likely to get delirium than others – including those of advanced age (over 65), and those with dementia, depression, anxiety, or other mental health challenges. Those with poor vision or poor hearing are also more likely to misinterpret their environment.

The impact and consequences of ICU delirium

The short-term consequences are that patients with delirium are more likely to spend longer on a breathing machine. They are more likely to get chest infections, bed sores, or clots – and as a result of that, they spend more time in the ICU.

Some patients make a quick and full recovery from delirium. Others go on to suffer from anxiety, depression and in rare cases, they might develop post-traumatic stress disorder (PTSD). This is because some patients have very vivid recollections and flashbacks, and this can affect their ability to return to ‘normal life’ – to function within the family and in society.

Delirium can affect not only the patient, but the family too. And the psychological impact of delirium can slow down the physical recovery from whatever the patient is in hospital for.

There is also some evidence that some patients may go on to develop what’s known as ‘dementia-like cognitive impairment’ – where they have trouble with thinking, concentration or memory. But seeking help early can minimise the risk of this.

Encouraging conversations

Not all patients flag up the delirium they have experienced to their care team. Some can’t even remember it taking place. Others don’t bring it up because they are embarrassed or scared to say they have these horrible nightmares or hallucinations.

They might feel ashamed of their irrational behaviour, and sometimes of how they behaved towards staff during that time. But as medical staff we are very used to patients with delirium, so we are very understanding and make no judgement.

Sometimes patients stay quiet because they think that talking about it will bring back distressing memories, so they try to deal with it by themselves.

ICU delirium is very common, but that doesn’t mean it’s normal, and we need to talk about it more. 

It’s important for patients to know that this kind of delirium is a well-known complication from critical care illness so if they talk to their specialist PH nurse about it, or go to their GP, they will understand. Don’t pretend it doesn’t exist; it’s really important to talk about it.

There is a lot of support available and the most important thing for patients to know is to know they are not alone. ICU delirium is yet another health problem they are battling, and it is nothing to be ashamed of.

We need to keep talking about it and keep on educating about it. It’s a difficult subject, but it’s an important one for everyone.”

  • Kate is a ‘delirium champion’ at Royal Papworth Hospital, one of 13 nursing staff members who have taken on the additional role to educate and raise awareness of ICU delirium amongst staff, patients and their families.

Click here to hear from people with pulmonary hypertension who have have experienced ICU delirium