Chapter 46: ICU Delirium

DEFINITION AND SUBTYPES

• Delirium: A form of acute and fluctuating global cerebral dysfunction caused by the direct physiologic consequences of a general medication condition and characterized by disturbances in attentiveness and awareness and cognitive impairment affecting memory, cerebral orientation, language, perception, and/or visual or auditory hallucinations. Four current subtypes exist:

  • Hyperactive: The “classic” form of delirium and intensive care unit psychosis featuring episodic or progressive agitation, restlessness, hallucinations, delusions, and/or emotional lability. Most easily recognized subtype by providers and family members.

  • Hypoactive: Can also be referred to as “encephalopathy of critical illness” with decreased responsiveness, blunted levels of consciousness, quiet confusion, and apathy. Oftentimes can be confused with depressive symptoms or acute stress disorders.

  • Mixed: Waxing and waning occurrences of both hyperactive and hypoactive delirium throughout its fluctuating course.

  • Subacute: Usually related to an indolent, progressive medical condition over time with occasional occurrences of either hyperactive delirium or hypoactive delirium or both that is not defined by an additional psychiatric diagnosis.

ETIOLOGY

• Often is multifactorial. Care should be made to evaluate for all of the following etiologies as a possible cause:

  • Underlying disease processes – most often associated with compensated or uncompensated shock; systemic or localized infection; acute or chronic hypoxia/hypoxemia; neoplasms; seizures; and/or electrolyte, renal, or endocrine derangements

  • Environmental exposures – prolonged states of immobilization or paralysis, day and night lighting disturbances, and sleep deprivation

  • Iatrogenic – suspected to be related to certain acute or prolonged drug exposures (i.e., sedative medicines like benzodiazepines, barbiturates, or opioids or anticholinergic medications) or withdrawal from previously utilized medications

IMPACT AND RECOGNITION

• Delirium is widely accepted as a negative predictor for clinical outcomes in adult patients, particularly those on mechanical ventilation and prolonged sedative infusions.

• Although pediatric data remains limited, emerging literature suggests similar risk factors for developing delirium and an impact on short- and long-term outcomes for children.

• Diagnosing and recognizing delirium in pediatric patients is difficult and is complicated by variations in pediatric development and age.

• Once diagnosed, delirium has been shown to predispose adult patients to:

  • Increased in-hospital mortality

  • Longer lengths of stay, both in the ICU and general hospital

  • Higher medical costs

  • Long-term cognitive impairments

  • Developing post-intensive care syndrome (PICS)

SCREENING TOOLS

• Utilization of quick, reliable, feasible, and observational screening tools for pediatric patients aids physicians in diagnosing all four delirium subtypes.

• Three tools are currently in use:

  • Preschool Confusion Assessment Method for the ICU (psCAM-ICU)

  • Pediatric Confusion Assessment Method for the ICU (pCAM-ICU)

  • Cornell Assessment of Pediatric Delirium (CAPD) - See Figure 46-1

• The psCAM-ICU and pCAM-ICU cannot be fully utilized on developmentally delayed children, which is a recognized limitation of these tools. The CAPD scale can be applied to all children regardless of delay.