Delirium in ICU
Delirium is a common problem in the critically ill, affecting between 60-80% of mechanically ventilated patients. The importance of trying to prevent and when present, treat this condition, has only recently been appreciated.
Delirium is a form of organ dysfunction affecting the brain, in much the same way as shock represents dysfunction of the cardiovascular system.
Core features of delirium:
1. A disturbance of consciousness (i.e. reduced awareness of the environment, with reduced ability to focus, sustain or shift attention)
2. A change in cognition (i.e. impaired problem solving or memory) or a perceptual disturbance
3. Onset within hours or days, with a tendency to fluctuate.
Other common features include:
- Intrusive abnormalities of awareness and affect, such as hallucinations (usually visual)
- Inappropriate emotional states.
Delirium is a syndrome with a wide range of presentations. Three subtypes of delirium are recognised:
1. Hyperactive delirium: Only 5-22% of such patients
2. Hypoactive delirium
3. Mixed delirium with fluctuation between hyperactive and hypoactive forms.
The hypoactive form is commonly overlooked unless appropriate testing is undertaken.