Delirium care

Guide to delirium care

Here is a concise guide to the fundamentals of delirium care in adults outside of ICU settings. If you would like more detail please see this open access article.

Here is a link to an overview talk.

Author: Alasdair MacLullich, Professor of Geriatric Medicine, University of Edinburgh

General background on delirium

Delirium is a rapid change in mental functioning. It usually arises over hours or days. This fast speed of onset is characteristic of delirium and contrasts with dementia which typically develops slowly over months or years.

Most delirium lasts a few days, but in some cases (around 20%) it lasts longer and can take weeks or even months to resolve. In some patients there is only partial recovery and they do not return to their pre-delirium state. During a period of delirium the features can come and go (fluctuate). For example, a patient may be confused, disorientated and fearful overnight but appear more calm and less confused mid-morning. Patients may even fluctuate during a brief consultation, for example falling asleep then waking up again.

People with delirium can present in different ways. The main abnormality is inattention, ranging from being barely responsive to voice (that is, severely reduced level of arousal), to being unable to engage in simple conversation and follow simple commands, to more subtle difficulties in maintaining focus over periods of 10-15 seconds.

People with delirium who are able to produce speech are usually confused, often showing an impaired understanding of what is happening to them. They are often distressed and anxious. They may also believe that they are at risk, for example feeling that they have been imprisoned or that staff or other patients are trying to harm them. Hallucinations are also common. They are mostly visual and can be very frightening.

Some people with delirium can appear very restless and hyperactive. This is often a consequence of fear in that they feel unsafe and want to leave to reach a place of safety or to be with family.

Delirium can be typed by psychomotor disturbance, with hyperactive, hypoactive (less responsive, drowsy) and mixed forms recognised. Hypoactive delirium is the most common but is more commonly undetected, particularly in older patients.

Below are the DSM-5 criteria for delirium. Note that the DSM-5 Guidance Notes state that “Low-arousal states (of acute onset) should be recognized as indicating severe inattention and cognitive change, and hence delirium.” This means that there is no separate classification of states such as ‘stupor’ or ‘obtundation’. Reduced level of arousal above the level of coma that is of rapid onset is usually delirium.

Delirium is caused by anything that can rapidly disrupt brain functioning. There is a long list of potential acute medical causes, including: infections (commonly urine or chest, but any almost infection can trigger delirium), trauma, surgery, constipation, drug side-effects (e.g. opioids or benzodiazepines), and sudden drug withdrawal (e.g. antidepressants).

Physiological and metabolic changes happening at the same time as acute illness such as low blood oxygen, high blood carbon dioxide, low glucose, high or low sodium, or high calcium can also directly cause delirium.

Acute psychological stress caused by hospital admission, pain, discomfort, disorientation, fear, isolation, and so on, can also trigger delirium, particularly in patients with dementia. Sleep disruption is also a cause.

The pathophysiology of delirium is incompletely understood. Because the brain is so complex and its function can be disrupted in many ways, it is likely that there are multiple possible mechanisms of delirium. These include direct causes like depriving the brain of fuel (oxygen, glucose) and toxic effects from drugs, and indirect causes such as peripheral inflammation triggering inflammatory and neurotransmitter changes in the brain. Currently there is no single mechanism thought to be consistently present in delirium, and so there is no simple drug treatment available. This fits with drug trials which have not shown drugs to be effective in delirium treatment (though see below for the limited circumstances in which drug treatment as part of delirium care can be considered).

Increasing age, dementia, frailty, multiple co-morbidities, and sensory impairments all increase the risk of delirium.

Delirium is very common in acute hospitals. One recent meta-analysis found an overall occurrence of delirium of 23% in medical patients. Particular groups are at higher risk, with 30% of older patients undergoing emergency surgery and 40-60% of intensive care patients developing delirium.

Importantly, in hospitals two-thirds of delirium is present on admission, with the remainder arising during the inpatient stay.