What is delirium

Delirium is an expression of acute brain failure. In DSM-5 (the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders), delirium is defined as: “a disturbance in attention and awareness. The disturbance develops over a short period, tends to fluctuate and with an additional disturbance in cognition”. Delirium is the most common surgical complication in older adults, but can occur in patients of any age (Source: Marcantonio, 2017, NEJM)


The impact of delirium

Delirium has a big impact on patients

Types of delirium

Suffering from delirium is stressful and can cause frightening thoughts or hallucinations. Although many clinicians think of patients with delirium as being in an agitated state, hyperactive delirium represents only 25% of cases, with the others having hypo- active (“quiet”) delirium. The classic teaching is that delirium is transient; however, a growing body of literature shows that this is not always the case. (Marcantonio, 2017, NEJM).

Hypoactive type

Hypoactive delirium is associated with a poorer prognosis, potentially because it is less frequently recognised. Patients with hypoactive delirium may often present as calm and mearly appear drowsy. This type of delirium is often confused with depression or dementia.

Mixed type

Patients with this type are occasionally restless.

Hyperactive type

Patients with hyperactive delirium are restless, often agitated, and are physically hyperactive.

The longer delirium lasts, the higher the impact

The complex and unclear clinical presence makes it difficult to recognise delirium. According to international guidelines and research, only 12% to 35% of delirium cases are currently recognised in clinical practice. This means that 65% to 88% of people with delirium do not receive the necessary treatment (Source: Marcantonio, 2017, NEJM).

To date, delirium detection is recognised too little and too late

There is a clinical need to improve delirium detection. Detection, monitoring and hence diagnosis through the use of questionnaires are missing the majority of delirium cases and often only detects the hyperactive type of delirium.

Complex and confusing

Approximately 33% of admitted patients over 70 years of age suffer from delirium. Half of this group is, on admission to hospital, already suffering from delirium. The other 50% of the elderly and fragile patient group will develop delirium during their hospital stay.  

Subjective and ineffective

In most hospitals, nurses are tasked with delirium detection. The patients who are at risk of delirium are monitored with a standardised checklist. Current screening tools are subjective, ineffective and often unused. Therefore, the diagnostic sensitivity varies and would appear to be related to the individual that does or does not apply any screening tool.


With DeltaScan, Prolira offers a solution to the problem highlighted above. Healthcare professionals can use DeltaScan to measure brain activity of their patients to determine the presence of delirium. This therefore makes DeltaScan a valuable supporting screening tool in the diagnosis of delirium.

Revision number: 2

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