ICU delirium: what it is, why it happens and how families can help

The NHS describes sudden confusion (delirium) as a state in which a person may not be able to think or speak clearly or quickly, may not know where they are, may struggle to pay attention or remember things, and may see or hear things that are not there. In intensive care this is usually called ICU delirium.

ICUsteps, the UK intensive care patient support charity, explains that delirium is a name for acute confusion and is sometimes described as being in a nightmare, but feels very real to those experiencing it. Patients may believe they are not in hospital, see threatening animals, think they have been kidnapped, believe staff are impostors, or think they or loved ones have died. They may try to get out of bed or demand to go home.

NICE says changes that may indicate delirium appear within hours or days and may affect thinking (worsened concentration, slow responses, confusion), perception (visual or auditory hallucinations), physical function (restlessness, agitation, reduced movement, changes in appetite, sleep disturbance) and social behaviour (withdrawal, difficulty engaging, changes in mood or attitude).

NICE also warns of hypoactive delirium, which is often missed, with signs such as withdrawal, slow responses, reduced mobility and movement, worsened concentration and reduced appetite. A relative who sees the patient as quiet and drowsy may therefore be seeing delirium rather than simply tiredness, and should tell the nursing team about changes they notice. ICUsteps notes that delirium can fluctuate, with moments of clarity followed by confusion.

The NHS says sudden confusion can be caused by many things, including infection, stroke or TIA, low blood sugar, head injury, some prescription medicines, alcohol withdrawal, carbon monoxide poisoning, and problems with the lungs or heart. In intensive care several of these can occur together.

NICE lists risk factors assessed at admission: being aged 65 or over, past or present cognitive impairment or dementia, a current hip fracture and severe illness. It also describes the things that contribute to delirium and are addressed in prevention: disorientation, dehydration or constipation, low oxygen levels, infection, immobility, pain, medicines, poor nutrition, sensory impairment and poor sleep.

NICE guideline CG103 says that if indicators of delirium are noticed, a competent practitioner should assess using the 4AT tool, but that in critical care the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) or the Intensive Care Delirium Screening Checklist (ICDSC) should be used instead. A healthcare professional with the relevant expertise then makes the final diagnosis, and it should be documented in the person's record, including their primary care record.

The guideline also recommends observing people at least daily for changes that may indicate delirium, and documenting them, which is why staff on ICU commonly screen patients routinely.

NICE says the first step is to identify and manage the possible underlying cause or combination of causes. It recommends effective communication, reorientation and reassurance, for example explaining where the person is, who they are and what your role is, and considering involving family, friends and carers.

If a person with delirium is distressed or considered a risk to themselves or others, NICE says to try verbal and non-verbal de-escalation first. If these are ineffective or inappropriate, it says to consider short-term haloperidol, usually for 1 week or less, starting at the lowest clinically appropriate dose. NICE also lists a tailored multicomponent prevention package that includes appropriate lighting, a 24-hour clock in critical care, visits from family and friends, fluids, treating infection, early mobilisation, pain assessment, a medication review, hearing and visual aids, and protecting sleep.

ICUsteps has produced a leaflet for relatives, called You Are Safe Here, created by an ICU research nurse and an ICU survivor and available in 11 languages. It offers words and approaches to reassure someone with ICU delirium that they are safe. ICUsteps also has a delirium information sheet.

The NHS first-aid advice for sudden confusion suggests staying with the person, telling them who you are and where they are, reassuring them, using simple words and short sentences, and not asking lots of questions. Clinical staff on the unit will advise what is appropriate in the intensive care setting NICE also recommends that hearing and visual aids are available and used by people who need them.

Patients and relatives are often left with questions after delirium. ICUsteps says that patients and relatives are not always aware of delirium and how it presents, and that its information, support groups and online community are available. Survivors may remember frightening dreams or hallucinations without realising they were part of delirium, and it can help to talk this through with the ICU follow-up team or a support group.

NICE notes that delirium in hospital can have serious consequences, including increased risk of dementia and death, and may increase length of stay. If confusion or memory problems continue after discharge, speak to your GP.