16 March 2022

Intensive care unit (ICU) delirium is very common. It affects up to 80 per cent of patients, but a lack of understanding, fear of judgement or even shame can stop patients seeking help.

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, and it can have a profound impact on their loved ones, too.

Prevention, recognition and education is vital – and so is speaking up if you are struggling with your own experiences.

Katarzyna (Kate) Zamoscik is a senior staff nurse in critical care and is a delirium champion at our 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.

Today (Wednesday 16 March) is World Delirium Awareness Day. Here is her guide to understanding ICU delirium…

ICU delirium is very common and it’s really important that we encourage understanding of it.
Kate Zamoscik
Senior nurse and delirium champion, Royal Papworth Hospital


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 are a lot of relatives 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.

Symptoms of ICU delirium

Patients may not remember why they are in hospital, and they may be hyper-alert and very observant of what is happening around them (so they will become ‘over-stimulated’).

They could also be 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 will be too drowsy to be aware of what’s going on around them. They will be lethargic, very quiet and unusually sleepy.

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

They can also 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.

Delirium often comes and goes and fluctuates throughout a 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

It can be a consequence of low oxygen level, 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 aged 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.

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 intensive/critical care.

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 all 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 hospital 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.

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 that they are not alone. ICU delirium is nothing to be ashamed of.

We need to keep talking about it and keep on educating both staff and patients about it.

It’s a difficult subject, but it’s an important one for everyone.

Patient case studies

"I experienced (in my mind) extended lucid periods when the staff were trying to kill me. Eventually when I was fully conscious, I recognised some of the staff which made it even more real and frightening. I finally opened up to a lovely nurse who gently explained that what I had experienced wasn’t real and helped me to realise that I had gone through a psychotic episode. She is a wonderful nurse and I feel like she saved me." 
Amanda, who experienced ICU delirium when she had her pulmonary endarterectomy (PEA) operation at Royal Papworth Hospital. 

I remember believing one nurse was going to hit me and I screamed.
Experienced ICU delirium after surgery

“The operation was successful, and I am now back to the things I used to do, but I was in hospital for a total of three weeks. I remember believing one nurse was going to hit me and tie me down or attack me and I screamed when she came back to do the night shift. That was awful."
Georgia, who also experienced vivid hallucinations whilst recovering from PEA surgery for chronic thromboembolic pulmonary hypertension (CTEPH)

Georgia and Amanda's stories can be read on the Pulmonary Hypertension Awareness UK website