Delirium is an acute, transient and reversible state of confusion, usually the result of other organic processes (infection, drugs, dehydration), the onset is acute and the cognition of the patient can be highly fluctuant over a short period of time.
One in five elderly patients on medical and surgical wards are affected by delirium at any one time.1
There are two main states of delirium, known as ‘hyperactive‘ and ‘hypoactive‘ delirium.
It is common for patients to fluctuate between these two states.
Hyperactive delirium is the ‘typical’ delirium presentation that most people are aware of.
Clinical features of hyperactive delirium include:
Hypoactive delirium is less well known and as a result, often missed or confused with depression.
Clinical features of hypoactive delirium include:
Slowness with everyday tasks
Aetiology and risk factors
A change in environment coupled with sensory impairment (common in the elderly) increases the risk of developing delirium. These factors alone can cause delirium without any deeper organic cause, but this should only be considered as a diagnosis of exclusion.
Things that can cause or lead to delirium include pretty much anything, ever. Some of the biggies are listed below. I’m generally not a fan of acronyms for the sake of acronyms, but CHIMPS PHONED is a useful reminder that it is not just our old friend ‘UTI’ that should be considered:
Organ dysfunction (hepatic or renal impairment)
Drugs (over the counter, illicit, alcohol and smoking)
Assessment of the confused patient
It is essential to perform a comprehensive assessment of all patients suspected of having delirium, given the wide range of possible causes and varying clinical features.
Taking a history directly from the patient may not be possible in the context of acute confusion (although you should always try):
Conversation can give big clues to the patient’s current mental state
Provide reassurance and gentle re-orientation if appropriate
Ask the patient what they are seeing/hearing/experiencing
Other useful sources of information include:
Collateral history (e.g. family, friends, nursing staff)
Medical notes (e.g. past medical history, current medications)
Useful information in the patient’s medical notes may include:
Past medical history (e.g. atherosclerosis, stroke, previous episodes of confusion, head injury, recent admissions)
Current medications: review for drugs that may cause or contribute to confusion (e.g. opiates)
Social history (e.g. how are they coping at home, excess alcohol, illicit drug use)
The Abbreviated Mental Test Score (AMTS) is a useful screening tool for assessing cognition.
This tool can be used to objectively monitor for improvement or deterioration in cognitive function over time.
Other cognitive screening tools which provide more detailed assessment include MMSE and ACE-III.
A thorough clinical examination (including assessment of vital signs) should be performed, looking for signs which may provide clues as to the underlying cause of confusion:
Vital signs (e.g. fever in infection, low SpO2 in pneumonia)
Level of consciousness (e.g. GCS/AVPU)
Evidence of head trauma
Sources of infection (e.g. suprapubic tenderness in urinary tract infection)
Asterixis (e.g. uraemia/encephalopathy)
When investigating why a patient might be confused, there are a standard set of further investigations which are often referred to as a ‘confusion screen‘. This panel of investigations is useful for identifying or ruling out common causes of confusion.
FBC (e.g. infection, anaemia, malignancy)
U&Es (e.g. hyponatraemia, hypernatraemia)
LFTs (e.g. liver failure with secondary encephalopathy)