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Delirium

Last updated 14th June 2019 - Tom Heaton
This is a good introductory video from the Osmosis team: https://www.youtube.com/watch?v=qmMYsVaZ0zo

Delirium is an acute neuropsychiatric disorder.
The key features of delirium are:
  1. Disturbed consciousness
  2. Disturbed cognitive function or perception
  3. Acute onset
  4. Fluctuating course

These features can help differentiate it from other conditions e.g. dementia.
There are 3 main forms that it can present:
  • Hyperactive
  • Hypoactive
  • Mixed

The pathophysiology is not well understood.
It may be a result of disruption of neurotransmitter levels or release, or the effect of inflammatory mediators in the brain.

Risk Factors

Clinical contributing factors
Patient
  • Age (>60)
  • Sensory impairment (hearing, visual)
  • Cognitive impairment/mental health issues
  • Medications (below)
Surgical/Illness
  • Electrolyte disturbance/dehydration
  • Poor nutrition
  • Constipation
  • Acute illness/infection
  • Drug withdrawal
  • Hypoxia
Anaesthetic/Intervention
  • Poor mobility - limited to ICU bed
  • Medication (below)
  • Sleep disturbance
  • Sensory overload e.g. lights and sounds on the ICU

Medication
These are a major risk, both in terms of taking or withdrawal.

Directly deliriogenic:
  • Analgesics - Pethidine, morphine, fentanyl, codeine
  • Hypnotics - benzopaines, thiopentone
  • CVS - atenolol, digoxin, dopamine
  • Corticosteroids
  • Other - furosemide, ranitidine

Affecting sleep cycle:
  • Benzodiazepines
  • Analgesics- opioids, NSAIDs
  • Antidepressants
  • CVS - beta blockers, amiodarone, dopamine
  • Anticonvulsants - phenytoin, phenobarbital

Features

Delirium may present as changes in behaviour:
Cognitive function - changes in concentration, responsiveness, confusion
Perception - hallucinations, delusions
Physical function - changes in mobility, movement, restlessness, agitation, appetite, sleep
Social behaviour - lack of cooperation, withdrawal, altered communication, mood change.

These fit in with the pattern of delirium described above, in that there are of acute onset and fluctuating.

Assessment

A full clinical history and assessment is important, but it is well recognised that delirium can be difficult to detect, especially in its hypoactive form.
The use of a validated assessment tool can improve the sensitivity of detecting delirium.
Examples:
  • RASS
  • CAM-ICU
  • Intensive care delirium screening checklist

CAM-ICU
Not possible if patient is deeply sedated of unconscious.
There is a stepped flowchart looking at:
  1. Acute change/fluctuating course in their normal mental status
  2. Inattention errors -
    1. “squeeze my hand every time I say the letter A”
    2. SAVEAHAART
    3. More than 2 errors is abnormal
  3. RASS - alert and calm () is normal
  4. Disordered thinking
    1. Questions designed to elicit this - does a stone float on water

There are good links to assessment tools here: http://gmccn.org.uk/delirium

Screening of high risk patients should be undertaken to ensure that it isn’t missed.
This will include essentially every patient on ICU.

Prevention

Non pharmacological interventions
  • Ensure good communication
  • Get family involved
  • Minimise changes in staff
  • Appropriate lighting
  • Clock and calendar
  • Reorientation
  • Minimise movement between sites
  • Cognitively stimulating activities
  • Mobilise as able
  • Detect and treat pain
  • Assess for infection
  • Reverse sensory impairment e.g. glasses, hearing aids
  • Promote sleep

Ensure medication review to minimise impact

Management

Identify and treat cause
Consider similar, serious medical conditions:
  • Withdrawal
  • Wernicke’s
  • Electrolyte/metabolic disturbance
  • Intracranial pathology e.g. infection
  • Toxicity
Reorientate
Consider involving family/friends
Optimise preventative measures
If needed, Low dose sedatives - olanzapine/haloperidol
Only if other efforts have failed

Communication with family is also important.
Can be very upsetting for family.

Incidence & Complications

30-60% of ICU patients
60-80% of ventilated patients
Undetected in ⅔

Complications include an increased risk of:
  • Death
  • Dementia
  • Long term neuropsychological disease
  • Prolonged ICU and hospital stay

Cognitive impairment can be in 50% of these patients at 12 months after their ICU delirium episode.
This may be reflected in increased care needs following an episode.
Mortality is increased by a factor of 3.2 at 6 months.

Links & References

  1. Osmosis. Delirium -causes, symptoms, diagnosis, treatment & pathology. Youtube. 2016. https://www.youtube.com/watch?v=qmMYsVaZ0zo
  2. Nickson, C. Delirium in ICU. LITFL. 2019. https://litfl.com/delirium-in-icu/
  3. Delirium. https://greatermanchestercares.co.uk
  4. Greater Manchester Critical Care Network. Delirium. http://gmccn.org.uk/delirium
  5. ICU Delirium. https://www.icudelirium.org/
  6. Shi, Q. et al. Confusion assessment method: a systematic review and meta-analysis of diagnostic accuracy. Neuropsych Dis Treat. 2013. 9:1359-1370 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3788697/​
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