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First posted November 2009 by Charles Gomersall
Definition
- Delirium: acute change in mental status or fluctuation in mood,
associated with:
- impaired attention
- disorganized thinking
- confusion
- altered state of consciousness
Usually acute in onset and varies in intensity during day with peak at
night. Usually reversible.
Easily detected in patient who is combative (active delirium) but may
also be present in a calm and quiet patient (hypoactive delirium).
Epidemiology
Delirium occurs in 15-40% of patients but is only detected in about 1/3 of
these patients. Associated with higher mortality, prolonged length of ICU stay
and increased healthcare costs
Risk factors
Pre-existing conditions
- age>70 years
- transfer from nursing home
- visual or hearing impairment
- depression, dementia, congestive heart failure, stroke or epilepsy
- renal impairment
- liver impairment
- HIV infection
- alcohol abuse in previous month
- psychotropic drug use
- malnutrition
Acute condition
- severe illness
- drug overdose or drug abuse
- metabolic
- hypo/hyperglycaemia
- hypo/hypernatraemia
- hypo/hyperthyroidism
- body temperature disturbance
- sepsis
- hypoxaemia
- dehydration
- intracerebral lesion
- brain trauma
- fits
Iatrogenic/environmental
- drugs:
- anti-cholinergics
- sedatives
- analgesics
- antibiotics, antihistamines, antihypertensives, bronchodilators,
diuretics, H2 blockers, steroids
- physical restraints
- tube feeding
- rectal or urinary catheter
- central venous catheter
Diagnosis
Diagnosis is often obvious in patients with active delirium but is harder to
detect in patients with the more common hypoactive or mixed pictures. In these
patients screening tools may be useful.
Step 1
Establish patient's pre-existing mental state - a large proportion of ICU
patients have some form of cognitive impairment prior to admission. Subsequent
tests for delirium must be interpreted in the light of this knowledge.
Step 2
Use screening tool to detect delirium
CAM-ICU
- Confusion Assessment Method for the Intensive Care Unit
- Most extensively validated score
- Disadvantage:
- requires patient to be able to evaluate and respond to a series of
questions. Patients with impaired consciousness for other reasons may
fail these tests and therefore be inappropriately classified as
delirious
- Patient classified as having delirium if has
features 1 AND 2 AND either 3 OR 4
ICDSC
- Intensive Care Delirium Screening Checklist
- Less specific than CAM-ICU but this may be due, in part, to the
inclusion of patients with neurological injury and structural neurological
abnormalities in validation study of ICDSC but not CAM-ICU. Also, in part
due to the inclusion of an assessment of sleep-wake cycle. Disturbance of
sleep-wake cycle is common in ICU but is not necessarily associated with
delirium
- Level of consciousness is the first domain - if this impaired to the
extent that vigorous stimulation is required to elicit a patient response
(or worse) then the evaluation is terminated
- Other domains are:
- inattention
- disorientation
- hallucination
- psychomotor agitation or retardation
- inappropriate speech or mood
- sleep/wake cycle disturbance
- symptom fluctuation
- screening is based on information collected from entire 8 h shift or
from previous 24 h
- Inclusion of a mandatory assessment of both consciousness and
psychomotor retardation may make it a better tool than CAM-ICU to detect
hypoactive delirium
Treatment
Non-pharmacological
- Reassurance
- Attention to patient comfort
- Consider physical restraints
- Correct potentially reversible risk factors
Pharmacological
- Usually a combination of sedation and neuroleptic eg haloperidol
- Use of dexmedetomidine for sedation is associated with shorter duration
of delirium compared to midazolam
Further reading
Chevrolet JC and Jolliet P. Clinical review: Agitation and
delirium in the critically ill -significance and management. Crit Care,
2007;11:214
Devlin JW et al. Delirium assessment in the critically ill.
Intensive Care Med, 2007; 33:929-40
Riker RR et al. Dexmedetomidine vs midazolam for sedation of critically ill
patients. JAMA, 2009; 301(5):489-99
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