Delirium

Delirium is defined in the American Psychiatric Associations Diagnostic and Statistical Manual of Mental Disorders as a disturbance of consciousness and cognition that develops over short period of time (hours to days) and fluctuates over time.
Many different terms have been used to describe the syndrome of cognitive impairment in critically ill patients include:
ICU psychosis, acute confusional state, ICU encephalopathy and acute brain syndrime. However, ICU delirium is the preferred term.
Important of delirium:
ICU delirium has been demonstrated to be an independent predictor of the length of hospital stay as well as ICU and 6-month mortality rates.
As many as 70-80% of ICU patients experience delirium. It is the most common mental disorder among elderly patients in the ICU. Sleep deprivation, sepsis, hypoxaemia, use of physical restrains, fluid and electrolytes imbalances, and metabolic and endocrine derangements have been implicated in the causation of delirium. On average, ICU patients sleep only 2 hours/day and less than 6% of their sleep is REM sleep.
Delirium is characterised by fluctuating disturbance of consciousness, cognition, concentration, memory and attention. Delirium can be categorised into subtypes according to psychomotor behaviour. Hypoactive delirium is characterised by decreased responsiveness, withdrawal and apathy. Whereas, hyperactive delirium is characterised by agitation, restlessness, and emotional liability.
Peterson and coworker observed that in a cohort of ICU patients; pure hyperactive delirium was rare (1.6%). In contrast, 43.5% of patients had purely hyperactive delirium and 54.1% had mixed delirium.

Mneumonics for Clinical Picture
Disordered thinking
Euphoria, fearful, depressed or angry
Language impaired
Illusions/delusions/hallucinations
Reversal of sleep-wake cycle
Inattention
Unaware/disoriented
Memory deficit

Important aetiologies of delirium:

Demented or elderly/Disturbed sleep/Dehydration
Electrolyte disturbance/Emotional stress
Lung or Liver failure
Intubation and ventilation
Renal failure
Infection/Injury
Use of catheters (e.g. venous or bladder) or physical restrains
Metabolic problems (e.g. thyroid)/Medication/Malnutrition

Delirium Assessment:
The Intensive Care Delirium Screening Checklist (ICDSC) being the most validated. It is an eight item delirium checklist (Bergeron, Intensive Care Medicine 2001).
The score of 1 is given if each of the following elements is met:
1. Altered level of consciousness: -non-responsive, poorly responsive, drowsy, or hypervigilant
2. Inattention -difficulty following instruction, cannot focus
3. Disorientation
4. Hallucinations, delusions, or psychosis
5. Psychomotor agitation or rertardation - hypo or hyper activity
6. Inappropriate speech or mood -inappropriate, disorganised or incoherent speech or inappropriate display of emotion
7. Sleep-wake cycle disturbance -sleep less than 4 hours or waking frequently at night
8. Symptom fluctuation
A SCORE OF 4 OR MORE IS CONSIDERED INDICATIVE OF DELIRIUM.
==> All patients should be regularly screened (8 hourly) for the presence of delirium.
The second validated tool is Confusion Assessment Method for the ICU (CAM-ICU) which is easy to use and requires minimal training.

Management:
1. Patient orientation and preservation of the sleep-wake cycle are important to minimise the risk of delirium.
2. Sedation with benzodiazepines should be avoided. Benzodiazepines SHOULD NOT be used for the treatment of delirium.
3. Dexmedotemidine is a promising drug for the prevention and treatment of delirium.
4. Haloperidol is recommended as the drug of choice for the treatment of delirium by the society of critical medicine (SCCM) and the American Psychiatric Association.
5. Melatonin has been suggested to reset the internal circadian rythm and sleep-wake cycle and may have a role in the treatment and prevention of delirium in ICU patients. Bourne and colleagues demonstrated that melatonin given at night increased the duration of sleep. The recommended dose is 2 mg.

interesting website: www.icudelirium.org