Delirium is an altered state of cognition, and up to 80% of critically ill patients suffer from delirium during the course of their ICU stay. Delirium is associated with worse outcomes, including increased risk of death, prolonged need for mechanical ventilation, prolonged hospital stay, long-term brain dysfunction, increased likelihood of post-discharge institutionalization, and increased cost of care.
Delirium is a disturbance in attention and cognition that develops over a short period of time (usually hours to a few days), representing a change from baseline attention and awareness, and tends to fluctuate in severity during the course of the day. Other common symptoms associated with delirium are: sleep disturbances, abnormal psychomotor activity, and emotional disturbances.
There are three subtypes of delirium that are categorized depending on the patient’s level of psychomotor activity and level of alertness.
- Hyperactive delirium is characterized by agitation, restlessness, hallucinations, delusions and emotional lability. These episodes of agitation are often accompanied by delusions and paranoia that can result in patients becoming combative and potentially harming themselves, or those around them including family members and staff. These patients commonly attempt to remove necessary medical equipment during these outbursts. This type of delirium can be difficult for family members to witness since patients act very differently from their normal self. Due to its outward, visible manifestations, hyperactive delirium is more readily diagnosed than hypoactive delirium.
- Hypoactive delirium is characterized by flat affect, lethargy, drowsiness, withdrawn attitude, apathy, decreased responsiveness, and slowed motor skills. Due to its insidious quality, hypoactive delirium is often misdiagnosed or undiagnosed. Studies have shown that hypoactive delirium is associated with higher mortality than hyperactive delirium.
- Mixed presentation: when patients fluctuate between the two subtypes.