Delirium after surgery: signs, causes, recovery and how families can help

Delirium is a state of sudden confusion with reduced awareness and attention. The Alzheimer's Society says the common feature is that people become less responsive or alert to things happening around them. It can look different from one person to the next: some people become agitated or distressed while others become drowsy or withdrawn.

After surgery it is often the brain's reaction to a physical problem. The Alzheimer's Society says delirium is usually the reaction of the brain to a separate problem, such as pain, infection, major surgery under general anaesthetic, injury, poor nutrition or dehydration, constipation or urinary retention, low blood oxygen, medicines, abnormal blood salts or sugar, or organ failure.

Guy's and St Thomas' says delirium usually affects people's brains for a short time, and that it can be a frightening condition for those who have it and for their families.

The most important sign, according to the Alzheimer's Society, is noticing a sudden change in a person's mental state, that they are "not themselves". Family, friends and carers are often best placed to notice this because they know them well.

• Being less alert and not responding to things happening around them.

• Being easily distracted, or not knowing where they are or what time it is.

• Suddenly being less able to do something such as walking or eating.

• Speaking less clearly or struggling to follow a conversation.

• Sudden swings in mood or behaviour.

• Seeing or hearing things that are not there, or strongly believing things that are not true.

• Sleepiness and withdrawal (hypoactive), or restlessness and agitation (hyperactive), or switching between the two (mixed).

• Symptoms that fluctuate; Guy's and St Thomas' notes they can change within a day and are often worse at night.

The Alzheimer's Society says hyperactive delirium may involve restlessness, pacing, resisting or responding aggressively to personal care, delusions and hallucinations. Hypoactive delirium involves seeming withdrawn, sluggish or tired, moving around less, being unusually sleepy and eating or drinking less.

It warns that hypoactive delirium is easy to miss because the person may just look tired or sleepy, and that it can go unnoticed when carers or healthcare workers are busy. Mixed delirium switches between the two during a day or from one day to the next.

The quiet form is therefore not milder in importance. Relatives who notice that someone is unusually sleepy, withdrawn or not drinking after an operation should tell the nurse or doctor.

The Alzheimer's Society lists dementia as the biggest single risk factor, being older than 65, being frail or having several medical conditions, poor hearing or vision, an unfamiliar or disorientating environment, sleep deprivation, not being able to sit up or move around, certain medicines particularly those that cause drowsiness, and having had delirium before.

Guy's and St Thomas' says people over 80 who have been diagnosed with some type of dementia are particularly at risk, and that delirium can happen in younger people too, especially if they are critically ill or after surgery.

The Alzheimer's Society says that with the right care delirium can often be prevented, and that when a person comes into hospital staff may check whether they are at risk and put measures in place.

In hospital, tell the nurse or doctor looking after the person about the changes you have noticed. The Alzheimer's Society notes that in England, if a person's condition is getting worse and concerns are not being responded to, there may be a way to ask for an urgent review by another clinical team, called Martha's Rule.

At home after discharge, sudden confusion needs medical attention. The NHS says to go to A&E or call 999 if someone suddenly becomes confused, because many causes need to be assessed and treated as soon as possible and sometimes may be life-threatening. It advises not to drive to A&E, but to ask someone to drive you or call 999.

While waiting for help, the NHS suggests staying with the person, telling them who you are and where they are, using simple words and short sentences, noting any medicines they take, not asking lots of questions and not stopping them moving around unless they are in danger.

The Alzheimer's Society says a doctor or nurse should assess the person's mental state as soon as possible, and that a short screening tool such as the 4AT, taking around two minutes, can help identify delirium more accurately. Once diagnosed, healthcare professionals try to work out the cause with a physical examination and tests such as blood tests, X-rays or scans.

It states that delirium is treated by resolving the health problems that have caused it, and that once this is done it is important to make conditions as ideal as possible for the brain to recover. Medicines to reduce hallucinations, delusions or aggressive behaviour are considered only if the person poses a risk of harm to themselves or others, or if symptoms are causing severe distress, and then a low dose of a sedative or antipsychotic may be tried for a few days.

The Alzheimer's Society says for many people the symptoms improve in a few days once the underlying causes have been treated. Some people do not make a quick or full recovery and may still have problems with memory and thinking several weeks or even months later, which is particularly common in older people who have had delirium after a major operation.

It adds that prolonged and severe delirium over several weeks can increase a person's risk of developing dementia. This does not mean delirium causes dementia, but if someone was already having problems with memory and thinking, it may speed up their decline so they develop dementia sooner.

Guy's and St Thomas' notes that not everyone remembers delirium, but those who do may find the memories distressing. Talking to the ward team or GP about those memories can help.

Delirium is managed by the surgical and medical team caring for the patient, whether in an NHS or independent hospital, usually with input from geriatric medicine or liaison psychiatry when it is severe or persistent. Recognising risk before an operation is part of good pre-operative assessment.

Before planned surgery, it is sensible to tell the team about any memory problems, previous delirium, regular medicines, and glasses or hearing aids, so that preventive steps can be planned. This applies equally to NHS and private hospitals.