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:
These features can help differentiate it from other conditions e.g. dementia.
There are 3 main forms that it can present:
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.
Delirium is an acute neuropsychiatric disorder.
The key features of delirium are:
- Disturbed consciousness
- Disturbed cognitive function or perception
- Acute onset
- 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
Medication
These are a major risk, both in terms of taking or withdrawal.
Directly deliriogenic:
Affecting sleep cycle:
Patient
- Age (>60)
- Sensory impairment (hearing, visual)
- Cognitive impairment/mental health issues
- Medications (below)
- Electrolyte disturbance/dehydration
- Poor nutrition
- Constipation
- Acute illness/infection
- Drug withdrawal
- Hypoxia
- 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.
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:
CAM-ICU
Not possible if patient is deeply sedated of unconscious.
There is a stepped flowchart looking at:
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.
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:
- Acute change/fluctuating course in their normal mental status
- Inattention errors -
- “squeeze my hand every time I say the letter A”
- SAVEAHAART
- More than 2 errors is abnormal
- RASS - alert and calm () is normal
- Disordered thinking
- 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 medication review to minimise impact
- 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:
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.
Consider similar, serious medical conditions:
- Withdrawal
- Wernicke’s
- Electrolyte/metabolic disturbance
- Intracranial pathology e.g. infection
- Toxicity
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:
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.
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
- Osmosis. Delirium -causes, symptoms, diagnosis, treatment & pathology. Youtube. 2016. https://www.youtube.com/watch?v=qmMYsVaZ0zo
- Nickson, C. Delirium in ICU. LITFL. 2019. https://litfl.com/delirium-in-icu/
- Delirium. https://greatermanchestercares.co.uk
- Greater Manchester Critical Care Network. Delirium. http://gmccn.org.uk/delirium
- ICU Delirium. https://www.icudelirium.org/
- 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/
