Share:
Next Lesson - Headaches
Contents
Abstract
- Delirium is a transient (short-lived) state of confusion due to an organic insult to the brain (a physical cause such as infection, a metabolic disturbance or a drug effect).
- It can present with hyperactive (restless and agitated) or hypoactive (withdrawn, quiet and sleepy) features.
- There is a myriad of different causes of delirium.
- Management of delirium centres on identifying and treating its underlying cause. It also involves reorientation (explaining where the person is, who they are and what your role is), reassurance and a suitable care environment.
- There are several tools for detecting delirium, among which are the Single Question to Identify Delirium (SQiD), the 4AT (a short bedside test with four items, each starting with the letter A) and the Confusion Assessment Method (CAM). NICE recommends the 4AT for assessment in most settings.
Core
Delirium (sometimes called an acute confusional state) is an abrupt change in the brain’s function that causes mental confusion and disturbs attention, perception and consciousness, with a fluctuating course. It is a transient state that develops over hours to days and is usually temporary: most episodes last a few days, although some persist for weeks or months. It is caused by an organic insult to the brain (a physical cause such as infection, a metabolic disturbance or a drug effect). This insult triggers acute disruption in the nervous system.
Delirium is different from dementia, which usually has a gradual onset and gets worse over time, with no cure at present. The two can occur together: people with dementia are more at risk of delirium, and the two can be hard to tell apart.
Patients typically present with an acute onset of confusion and/or agitation. Their consciousness can be clouded on presentation and will commonly fluctuate multiple times in one day. Delirium can also be accompanied by visual hallucinations (seeing things that are not there) or persecutory delusions (fixed false beliefs that other people intend harm).
Delirium can be classified into hyperactive, hypoactive, or mixed. A hyperactive presentation will usually be more obvious as patients will present restless, agitated, and even aggressive (especially if they are experiencing hallucinations). On the other hand, hypoactive presentations can be harder to spot, especially if there is a background of dementia or depression. Hypoactive delirium is the most common subtype, so it is important to look for it if delirium is suspected. A hypoactive patient will present more withdrawn, quiet, and sleepy. During an episode of delirium, a patient can fluctuate between both presentations, and this is a mixed presentation. Symptoms are usually more pronounced later in the day or at night (sometimes referred to as sundowning).
If indicators of delirium are identified, NICE recommends assessment with the 4AT by a practitioner competent to use it. The 4AT is a short bedside test with four items, each starting with the letter A. In critical care or the recovery room after surgery, use the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) or the Intensive Care Delirium Screening Checklist (ICDSC) instead. If the assessment indicates delirium, a healthcare professional with relevant expertise should make the final diagnosis. A history from someone who knows the patient helps establish any change from their usual cognition (thinking and memory) and behaviour.
The Confusion Assessment Method (CAM) assesses four features: acute onset and a fluctuating course, inattention, disorganised thinking, and an altered level of consciousness. For a positive assessment using the shortened CAM screening algorithm, the first two features must be present, together with either disorganised thinking or an altered level of consciousness. A patient can be fully alert and still have a positive CAM, because disorganised thinking can take the place of an altered level of consciousness. A positive CAM supports further clinical assessment for delirium; it does not replace clinical judgement. Some modified short versions accept either acute onset or a fluctuating course, to improve sensitivity; the original validated algorithm requires both.
Similarly, the 4AT uses a score of 4 or higher to indicate possible delirium and the need for further assessment. A score of 1 to 3 suggests cognitive impairment without delirium. A score of 0 suggests no delirium and no moderate or severe cognitive impairment, although it does not completely exclude either. The total (out of 12) is calculated by assessing four items. Alertness scores 0 if normal (fully alert, not agitated) and 4 if clearly abnormal. The AMT4 (Abbreviated Mental Test 4) asks for age, date of birth, place and the current year. Two or more mistakes score 2, one mistake scores 1, and no mistakes score 0. Attention is usually assessed by asking for the months of the year backwards, and scores 0, 1 or 2. Acute change or fluctuating course scores 0 if absent and 4 if present.
Once diagnosed, it is very important to find the underlying cause of delirium in order to provide appropriate management and resolve the episode. There is a myriad of disturbances that can cause delirium, so it is important to approach it in a systematic way. The mnemonic DELIRIUM (a memory aid) lists some contributing factors. Some letters cover more than one potential cause:
- Drugs: it is important to keep this one at the top of your list. Taking too much of a drug can cause toxicity, and stopping some drugs suddenly can cause withdrawal. Both can contribute to delirium. Key drug classes that can contribute include:
- antiparkinsonian drugs (used for Parkinson’s disease)
- anticholinergics (drugs that block the action of acetylcholine, a chemical messenger in the nervous system)
- antidepressants (used for depression)
- antipsychotics such as haloperidol (used for psychosis, where a person loses touch with reality)
- benzodiazepines (sedatives)
- opioids (strong painkillers such as morphine)
- recreational drug or alcohol intoxication or withdrawal
- Electrolyte Imbalance: it is important to look at the urea and electrolytes (U&Es).
- Low O2: hypoxia.
- Infection or Inflammation: urinary tract infections, sepsis, encephalitis (inflammation of the brain), central nervous system abscess, post-surgery infection etc.
- Retention: urinary (being unable to empty the bladder) or faecal (constipation).
- Ischaemia: stroke or myocardial infarction (heart attack).
- Under-Nourished or Under-Hydrated: malnutrition or dehydration.
- Metabolic Disorder: renal failure, hypoglycaemia (low blood sugar, especially in patients with diabetes).
This mnemonic is not a complete list. Other things can also contribute to the development of delirium. Examples include sensory deficits (for example patients who need glasses or hearing aids but do not have them), pain that is not adequately controlled, or post-ictal states (for example following a seizure).
There is often more than one contributing factor in an episode of delirium. All possible causes should therefore be carefully considered and identified so that the delirium can be treated.
Management of delirium essentially consists of treating the underlying cause, together with supportive care. NICE advises clear communication, reorientation (explaining where the person is, who they are and what your role is) and reassurance in a suitable care environment. Consider involving family, friends and carers to help with this. If a person with delirium is distressed or a risk to themselves or others, first use verbal and non-verbal techniques to de-escalate (calm) the situation. Short-term haloperidol (an antipsychotic drug, usually for 1 week or less, starting at the lowest clinically appropriate dose) may be considered if these techniques are ineffective or inappropriate. Haloperidol carries risks of cardiac and neurological side effects, particularly in older people. The British National Formulary (BNF, the UK prescribing reference) lists Parkinson’s disease and dementia with Lewy bodies (a type of dementia) as contra-indications, so haloperidol should not be given to these patients. A baseline ECG and correction of any electrolyte disturbance are recommended before starting haloperidol, with cardiac monitoring during treatment. If delirium does not resolve, re-evaluate for underlying causes and assess for possible dementia. Delirium itself is associated with an increased risk of subsequent dementia, higher mortality and longer hospital stay. NICE notes that delirium can be prevented and treated if it is dealt with urgently, so it should be recognised and managed promptly.
To sum up, delirium is an important diagnosis to keep in mind in every specialty. It is especially important when dealing with elderly patients, those with dementia, or those with a hip fracture or severe illness. It is important to ask ‘Is this patient more confused than usual?’ This is close to the Single Question to Identify Delirium (SQiD), which is put to a relative, friend or carer: ‘Do you think (patient’s name) has been more confused lately?’
Edited by: Dr. Maddie Swannack
Reviewed by: Dr. Thomas Burnell and Dr. Marcus Judge
Quiz
- 796
