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Contents
Abstract
- Delirium is a transient state of confusion due to an organic insult to the brain.
- It can present with hyperactive or hypoactive features.
- There is a myriad of different causes of delirium.
- Management of delirium consists in treating its underlying cause.
- There are several screening tools for delirium, among which are SQiD, 4AT, and CAM.
Core
Delirium is defined as an abrupt change in the brain that causes mental confusion, emotional disruption, and changes in consciousness. It is a transient state which can last for hours to days and is caused by an organic insult to the brain which triggers acute disruption in the nervous system.
This is different from dementia, which has a gradual onset and is an irreversible condition.
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. It can also be accompanied by visual hallucinations or persecutory delusions.
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, hence it is important to look for signs of it if suspected. A hypoactive patient will present more withdrawn, quiet, and sleepy. During an episode of delirium, a patient’s mood can fluctuate between both presentations, and symptoms are usually more pronounced later in the day or at night (sometimes referred to as sundowning), and this is a mixed presentation.
If indicators of delirium are identified, NICE recommends assessment with the 4AT by a practitioner competent to use it. In critical care or the recovery room after surgery, use CAM-ICU or 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 and behaviour.
The Confusion Assessment Method (CAM) assesses four features: acute onset or 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. Normal alertness therefore does not exclude a positive CAM assessment when the other required features are present. This result supports further clinical assessment for delirium rather than replacing clinical judgement. The original validation algorithm used acute onset and fluctuation; the author’s training manual describes the OR criterion for the shortened screening version.
Similarly, the 4AT uses a score of 4 or higher to indicate possible delirium and the need for further assessment. This is calculated by assessing alertness (0 or 4), AMT4 (DOB, Age, Place, Year - 2 or more mistakes score 2, 1 mistake scores 1, 0 mistakes score 0), Attention (usually assessed by asking the months of the year backwards scored 0, 1 or 2), and Acute change or fluctuating course (0 or 4).
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. To help remember some contributing factors more easily they are listed below in a mnemonic of DELIRIUM, though there are some letters with more than one potential cause listed under them:
- Drugs - it is important to keep this one on top of your list as both withdrawal and uptake of a drug in inappropriate doses can cause toxicity. Key drug classes that can contribute include: antiparkinsonian, anticholinergics, antidepressants, antipsychotics, benzodiazepines, opiates and recreational 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, central nervous system abscess, post-surgery infection etc.
- Retention - urinary or faecal.
- Ischaemia - stroke or myocardial infarction.
- Under-Nourished or Under-Hydrated - malnutrition or dehydration.
- Metabolic Disorder - renal failure, hypoglycaemia (especially in diabetes patients!).
This mnemonic is not a complete list, as there are other things that can contribute to the development of delirium, such as sensory deficits (for example patients with sensory impairments that are missing aids such as glasses or hearing aids), pain that is not adequately controlled, or post-ictal states (for example following a seizure).
It is also key to note that there is often more than one contributing factor of delirium. It is important to note that there is often more than one cause responsible for an episode of delirium and thus, all possible causes should be carefully considered and identified in order to treat it.
Management of delirium essentially consists of treating the underlying cause and prognosis is often dependent on how quickly the cause is identified. Delayed management is associated with an increased risk of subsequent dementia, higher mortality, and longer hospital stay.
To sum up, delirium is an important diagnosis to keep on the back of your mind, no matter the specialty you are working in but especially when dealing with elderly patients or those with dementia, and it is important to ask ‘Is this patient more confused than usual?’
Edited by: Dr. Maddie Swannack
Reviewed by: Dr. Thomas Burnell
Quiz
- 775
