Delirium

Delirium is an acute state of confusion or otherwise disorder mental state caused by somatic (non-psychiatric) illness. It is characterised by lack of the attention and awareness of the environment, and disordered stream of thought. Patients are usually disorientated, confused, have amnesia, are agitated, and have hallucinations (most commonly visual). It usually worsens at night, and develops over a short period of time. The patient may be hypoactive or hyperactive.

Delirium mostly affects elderly (> 65 years), due to their reduced physiological reserves. It's a very common condition, affecting almost 30% of elderly patients at some point during hospitalisation; in addition to this, it's probably underdiagnosed. It’s clinically relevant because it increases mortality, prolongs the hospital stay, and increases reintubation rate. It usually occurs during acute illness and is therefore common in the hospital, especially the ICU. It’s especially common in the ICU because many of the patients are elderly and because there is a lot happening at night in the ICU, so sleep withdrawal is common.

It's one of the neurocognitive or organic mental disorders, disorders characterising reduced brain function due to non-psychiatric illness.

Etiology

Delirium can be caused by many disorders. The mnemonic I WATCH DEATH can be used to remember them:

• Infection (even a small UTI)
• Withdrawal (alcohol, benzodiazepines)
• Acute metabolic (acidosis, electrolyte disturbance, liver failure, kidney failure)
• Trauma (especially to the head)
• CNS pathology (stroke, tumour, seizures, hypoxia))
• Hypoxia of the brain
• Deficiencies
• Endocrine
• Acute vascular
• Toxins (drug intoxication (illicit drugs, anticholinergics))
• Heavy metal poisoning

Clinical features

Delirium develops over a short period of time and fluctuates during the course of a day, usually worsening during the night. Characteristic for delirium is:

• Disturbed attention (e.g. unable to name months of the year backwards)
• Disturbed awareness (e.g. not oriented to time and space)
• Disturbed memory, language, perception, or visuospatial ability

Delirium may manifest as psychosis, with hallucinations, delusions, or thought disorder.

We distinguish two major types of delirium based on the clinical presentation, hyperactive delirium and hypoactive delirium.

Hyperactive delirium

The hyperactive delirium is the most commonly diagnosed form, characterised by restlessness, agitation, trembling,

Hypoactive delirium

Hypoactive delirium is probably under-diagnosed as it's easier to miss than the hyperactive form. It's characterised by increased drowsiness, lethargy, and inactivity.

Hypoactive delirium likely has a worse prognosis than the hyperactive form.

Diagnosis and evaluation

The diagnosis is clinical, and should be suspected in all elderly with an altered mental status. Determining and treating the underlying cause is essential. Labs, medication review, and medical history may provide clues to the etiology.

Screening

The patients can be screened with the intensive care delirium screening checklist (ICDSC) or confusion assessment method in the ICU (CAM-ICU).

Management

There is no causative treatment for delirium; treating the underlying cause is the aim.

Environmental and interpersonal measures are essential in symptomatically managing delirium. The hospital environment itself, with all its noises and busy personell, worsens the confusion. One must try to avoid these worsening factors. Frequent reassurance, verbal orientation, pain management, maintainance of hydration, and mobilisation are all helpful in improving the symptoms of delirium.

Agitated patients

In some cases of hyperactive delirium, patient behaviour may interfere with patient care or safety. Physical restraint should be avoided if possible, but may sometimes be necessary.

If all else fails, low-dose antipsychotics can be used to treat severe agitation in delirium. Haloperidol is often used. It can be administered intramuscularly if necessary. Benzodiazepines should be avoided as they may worsen the condition.