Delirium is a syndrome of acute change in mental status, characterized by inattention and fluctuation, due to precipitating factors or noxious insults.

It is best thought of as “acute brain failure,” much in the same way as acute kidney injury — it is often caused by a medical precipitant, requires urgent evaluation and treatment, and is associated with worse immediate and long-term outcomes.

The development of delirium is thought to depend on the vulnerability of the patient (predisposing factors) and the magnitude of the noxious stimuli and insults (precipitating factors).

Dementia and delirium are like acute kidney injury and chronic kidney disease

• The AKI = delirium, CKD = dementia
• AKI is risk for CKD, CKD is risk for AKI.
• In CKD, smaller insults can result in AKI
• The more advanced the dementia, the more vulnerable the brain to smaller noxious precipitating factors

Pathophysiology (Nature – Mechanism/pathophysiology; Delirium – pathophysiology)
There are proposed mechanisms but no unifying mechanism:

-Cytokines/systemic inflammation?
-Neurotransmitters?
–Cholinergic deficiency
–Dopamine excess

The pathophysiology is probably multifactorial but this is an area of ongoing research.

Delirium is extremely common in older adults, especially in sick patients!

Unit Overall Occurrence
Surgical ~30-70%
Medical
-General ~30-50%
-Intensive ~25-80%
Post-acute/ ~35%
Long-term Care
Emergency dept. ~10-15%
Community ~1-2%

Adapted from Inouye SK, Westendorp RG, Saczynski JS. Delirium in elderly people. Lancet. 2014;383(9920):911-922. doi:10.1016/S0140-6736(13)60688-1

• Increased hospital length of stay,
• falls,
• worse cognition,
• worse physical function,
• complications in SNFs
• rehospitalizations,
• and death.

A 2010 JAMA meta analysis found that delirium in hospitalized elderly is independently associated in a 2.4x increase risk of institutionalization, 2x increase risk of death, and 12.5x risk of dementia even after controlling for confounding by age, sex, dementia, comorbidities, and illness severity

According to Postoperative Delirium in Older Adults: Best Practice Statement from the American Geriatrics Society, the implementation of the 10 interventions below (monitored by an interdisciplinary team) has been showed to reduce delirium rates by 30-40% in the hospital!

1. Sensory enhancement (ensuring glasses, hearing aids, or listening amplifiers)
2. Mobility enhancement (ambulating at least twice per day if possible)
3. Cognitive orientation and therapeutic activities (tailored to the individual)
4. Pain control with scheduled acetaminophen if appropriate
5. Cognitive stimulation (if possible, tailored to the individual’s interests and mental status)
6. Simple communication standards and approaches to prevent the escalation of behaviors
7. Nutritional and fluid repletion enhancement
8. Sleep enhancement (daytime sleep hygiene, relaxation, non-pharmacologic sleep protocol, and nighttime routine)
9. Medication review and appropriate medication management
10. Daily rounding by an interdisciplinary team to reinforce interventions

Imagine the reduced healthcare burden, improved functional and cognitive outcomes, and reduced mortality if 30-40% of delirium cases in the hospital were prevented.

The Delirium Triage Screen is a 10 – 20 second screen designed by Vanderbilt University to rapidly rule-out delirium in busy clinical environments, namely the emergency room, and has a 98% sensitivity and 55% specificity.

There are two components:

1. Richmond Agitation Sedation Scale (RASS) assessment
2. “Can you spell the word “LUNCH” backwards?

A positive result is a RASS other than 0, OR, 2+ spelling errors. A positive result needs to be confirmed by confirmatory testing (see Diagnosing Delirium)

A common nursing screen is the Nursing Delirium Screening Scale (NuDESC). With a sensitivity of 86% and specificity of 87%, the NuDESC measures 5 domains:

• Disorientation
• Inappropriate behavior
• Inappropriate communication
• Illusions/Hallucinations
• Psychomotor Retardation