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Delirium

Delirium (sometimes called ‘acute confusional state’) is a common clinical syndrome characterised by;

  • Disturbed consciousness, sleeplessness, restlessness
  • Cognitive dysfunction, impaired memory, anxiety and delusions or agitation
  • Altered perception, emotional changes 

It has an acute onset and fluctuating course. Patients’ behaviour can often change dramatically over minutes to hours. Delirium may develop at any point in the patients ICU stay and continue into the ward environment. It has been shown to be a contributor to increased morbidity and mortality in the ICU patient.

Assessment of ICU patients for delirium
ICU patients should be monitored using validated delirium assessment scoring systems. Patients with delirium have been shown to have longer hospital stays and worse outcomes. Research suggests that delirium may be associated with cognitive impairment that persists months to even years after discharge from ICU.

Scoring systems and tools available
There are a number of validated delirium screening tools for use with critically ill patients. These scoring systems can be used to help diagnose delirium in ICU patients, and include:

CAM-ICU - Confusion Assessment Method for the ICU

ICDSC -Intensive Care Delirium Screening Checklist

DDS - The Delirium Detection Score (Otter et al, 2005)

The CAM-ICU is easily reproducible and has been demonstrated to increase the likelihood of the assessment being carried out by ICU staff. Routine daily screening of ICU patients is recommended (NICE, 2010 or www.nice.org.uk/CG103)

Classification of delirium
Delirium can be categorized into three main subtypes, according to the patient’s psychomotor behaviour:

  • Hypoactive - decreased responsiveness, withdrawal, and apathy
  • Hyperactive - agitation, exaggerated pain, abnormal haemodynamics, restlessness, and emotional lability
  • Mixed delirium – combination of hyper and hypoactive delirium

The hyperactive type is often well recognized due to the overt behaviour displayed by the patient. The hypoactive type is less well recognized and often misdiagnosed as depression.

Causes of delirium?

  • Drugs - Side effects of some of the prescribed drugs, or withdrawal of alcohol or other drugs
  • Sepsis
  • Renal or hepatic encephalopathy
  • RS - Hypoxia/hypercarbia/chest infection
  • CVS disease - hypotension, endocarditis, acute coronary syndromes
  • CNS disease - encephalitis, meningitis, head injury, space occupying lesion, post-ictal states, traumatic brain injury
  • Sleep deprivation (especially REM sleep)
  • Metabolic disorders - hypo/hyper-glycaemia, -natraemia, -calcaemia
  • Hypo/hyperthermia
  • Thiamine deficiency

Patients most likely to develop delirium in the ICU

  • Older age
  • Immobility
  • Chronic illness
  • Cerebral Illness (ie. Alzheimers, stroke)
  • Recreational drug users
  • Alcohol/ Substance abusers
  • Significant co-morbidities
  • Polypharmacy

Management of delirium
First rule out any of the above causes and remove any potential organic drivers. Unless your patient or others are at an imminent risk of harm it is advisable to treat using non-pharmacological methods in the first instance. Pharmacological agents include the use of antipsychotics/neuroleptic agents (ie. haloperidol, risperidol, quetiapine, and olanzapine). The dose and route required is dependent on the patients’ level of disturbance and co-morbidities and is titrated according to the desired therapeutic effect. Patients receiving antipsychotics/neuroleptic agents should be closely monitored for adverse side effects such as QT prolongation, arrhythmias and extrapyramidal symptoms.Benzodiazepines should be avoided although short acting benzodiazepines may beuseful in managing patients who have delirium associated with benzodiazepines or alcohol withdrawal. For more guidance (UKCPA, 2006).

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