ICU Delirium

Background

Delirium (interchangeable with Encephalopathy) is a clinical diagnosis based on DSM-5 criteria:
- Disturbances in attention (i.e. reduced ability to direct, focus sustain and shift attention).
- Change in cognition (e.g. memory deficit, disorientation, language disturbance, and perceptual disturbance) not better explained by a preexisting or evolving dementia.
- The disturbance develops over a short period (hours – days) and fluctuates during the course of the day.
- There is evidence from the history, exam, or lab findings that the disturbance is caused by a direct physiologic consequence of an organic medical condition, intoxicating substance, medication, or multiple causes
- Can present as hyperactive (agitated, trying to leave bed, etc.), hypoactive (somnolent, minimally interactive, etc.), or mixed.
- Hypoactive delirium is more common among older persons, often goes unrecognized, and is associated with higher rates of complications and mortality compared to hyperactive delirium.
Associated with higher morbidity and mortality compared to those who do not experience delirium and duration of delirium also associated with higher morbidity and mortality.
Very well-studied at VUMC, more resources found at icudelirium.org.

Evaluation of delirium in ICU patients becomes more difficult to assess when patients are sedated, intubated, etc.
When any altered mentation is suspected, start with gathering collateral history from family, friends, and caregivers to understand the patient’s baseline mental function (i.e. memory, ADL’s, mood) and last known normal.
Do neuro exam to rule out focal deficits. See “ICU-focused neuro exam” in Neurology section.
- Consider sedation when doing neuro exam as propofol and other anesthesia dampens brainstem + peripheral reflexes.
Always remember patients can be encephalopathic and evolve another acute neurological syndrome. Follow up any odd/changing exam findings.
ICU nurses use CAM-ICU for scoring q4h as part of routine ICU care.
See RASS scoring table in ABCDEF Bundle Critical Care chapter.

Most typically due to changes in environment, alterations in sleep cycle, and reduced cognitive reserve from critical illness.
Other differentials fit in a modified VITAMINS PO mnemonic

VITAMINS PO
Vascular	Ischemic stroke, Intracranial hemorrhage, Hypertensive encephalopathy, Severe hypotension or shock
Infection	UTI (most common), Pneumonia, Skin infections, Sepsis, CNS infections
Toxins/Medications	Anticholinergics, Benzos, Opioids (especially serotonergic opioids), Antipsychotics, Polypharmacy (≥5 medications), Drug-drug interactions, Alcohol or substance intoxication
Autoimmune	Autoimmune encephalitis, SLE, CNS vasculitis, among others
Metabolic	+Constipation +Hypo/hyperthyroidism, hypoglycemia, AKI, hypercalcemia, hyperammonemia (↑ Hepatic encephalopathy), severe hyponatremia, Uremia among many others +Vitamin deficiencies – thiamine, B12, B3, Vit D
Iatrogenic	Post-operative delirium, restraint use, prolonged intubation, bladder catheterization, sleep deprivation
Neoplasm, Neurologic	Brain mets, primary CNS tumors, CA associated with paraneoplastic syndromes (SCLC, Multiple myeloma, ovarian teratoma, etc.), seizures, postictal state, dementia, neurodegeneration
Substance withdrawal	Alcohol (delirium tremens), Benzodiazepines, Opioids, SSRIs, other daily psychiatric medications, other sedative-hypnotics
Pain	Always important to consider, especially in geriatric pts
Organ failure	Hepatic encephalopathy (ammonia), Uremic encephalopathy (urea), Respiratory failure (hypoxia, hypercapnia), CHF, Acute MI

Initial toxic/metabolic/infectious workup can include: CBC, CMP, TSH, Folate, Vitamin B12, UA, blood cultures, CT Head w/o. Look through med list to see if there are any sedating medications that could be contributing and try to minimize as much as possible.
Definitive treatment is addressing underlying etiology.
First-line symptomatic treatment includes delirium precautions, such as keeping blinds open during daytime, limiting daytime naps, redirection when agitated, lights on during day, TV on during day, family at bedside (opposite of these at night). There is an order in Epic called Nursing: Delirium Care, which can be found as part of the Geriatric Delirium Care order set, that has all these precautions listed out.
Although they do not provide mortality benefit in ICU delirium patients (and debatably worsen mortality), antipsychotics can be used if needed for more severe agitation IE pulling at lines, physical aggression. Start with one-time dose of zyprexa 2.5 mg or 5 mg, can escalate to 1 mg haldol if refractory. Check an EKG for QTc prolongation (>440ms) prior to giving.
Melatonin can be added to promote healthy sleep/wake cycle. Start with 3mg and best scheduled for 1800.