Understanding Delirium

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.

      1. 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.
      2. Hypoactive delirium is characterized by flat affect, lethargy, drowsiness, withdrawn attitude, apathy, decreased responsiveness, and slowed motor skills.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.
      3. Mixed presentation: when patients fluctuate between the two subtypes.

Read more about delirium in the ICU in the excellent review.

Risk factors for developing delirium

While any patient in the ICU is at risk for developing delirium, numerous risk factors have been identified. These risk factors range from the patient’s age, medical co-morbidities, and level of education to environmental factors like access to daylight in the ICU, noise level, and sleep deprivation. However, the four most important predisposing factors are:

  1. Pre-existing dementia
  2. Hypertension
  3. History of alcohol use (> 2 drinks per day)
  4. Severity of illness at the time of admission

Learn more about risk factors for delirium.

For a comprehensive resource, check out the Society of Critical Care Medicine Guidelines for the management of delirium.

Preventing Delirium: Interventions that benefit everyone

There are numerous strategies for preventing delirium which, when used together, can be very effective.

Non-pharmacologic strategies

These simple strategies for reducing delirium can be some of the most powerful and include:

  • Ensuring frequent reorientation
  • Providing access to eyeglasses and hearing aids
  • Ensuring that clocks and calendars are visible
  • Encouraging family presence and involvement in care
  • Incorporating cognitively stimulating activities
  • Implementing protocols to establish normal sleep/wake cycles
  • Minimizing the use of physical restraints
  • Treating pain adequately

Thoughtful Sedation

Sedating medications which are frequently required in the ICU can contribute significantly to the development of delirium. When it is necessary to use sedatives, a few guidelines can help minimize the chance that they will contribute to the development of delirium.

  • Use of targeted sedation scales (such as RASS or SAS)
  • Avoiding deep sedation when possible
  • Effectively treating pain before resorting to other sedatives
  • Implementation of daily awakening and spontaneous breathing trials
  • Avoiding benzodiazepines when possible

Early Mobilization

Mobility in the ICU has many benefits and including a possible reduction in the incidence and duration of delirium. Early (within 48 hours of admission) and progressive mobilization can help substantially reduce the chance that a patient will go on to develop delirium and has been associated with decreased need for sedation, as well.

Screening for Delirium in the ICU

Many tools have been developed to screen for delirium in ICU patients. While hyperactive delirium is readily evident to most observers, hypoactive delirium can be harder to detect but has been associated with worse outcomes. Implementing a protocol to screen patients regularly for symptoms of delirium can help to identify patients with delirium earlier in the their course and allow for effective interventions to be deployed. Some common screening tools which have been found to be reliable include the CAM-ICU (Confusion Assessment Method for the ICU) and ICDSC (Intensive Care Delirium Screening Checklist).

Learn more about screening for delirium in the ICU »

Treating Delirium

In addition to the measures described above, medications can be used to treat delirium if it develops. Pharmacologic therapies are aimed at managing and reducing the length, symptoms, and severity of delirium. While there are not any FDA approved pharmacologic therapies for the treatment of delirium, antipsychotics are often the mainstay treatment to manage hyperactive delirium or to reduce duration and severity of delirium in patients who are refractory to maximal non-pharmacologic efforts.

While intravenous haloperidol has been historically used, with growing use of atypical antipsychotics and the association between prolongation of the QT interval and haolperidol use, it is no longer recommended for use in the treatment of delirium. Atypical antispychotics may have some efficacy in reducing the duration of delirium and can assist with management of the agitation associated with hyperactive delirium. Many of these agents also have effects on the QT interval and should be avoided in patients at risk for developing Torsades de Pointes. In patients receiving antispychotic therapy, it is recommended to follow the QT interval periodically with an EKG.

For patients unable to receive antipsychotic therapy but who have agitation associated with delirium (not related to alcohol or benzodiazepine withdrawal), dexmedetomidine may be a superior alternative to benzodiazepines and other sedative agents.

Check out the ICU Delirium website for another great resource.

Next: Goals of Care

The most important things you need to know when patients and providers are aiming for different outcomes.

Learn more