26: Delirium


CHAPTER 26
Delirium


Anil Ramineni1 and Neha Dangayach2


1 Lahey Hospital and Medical Center, Burlington, MA, USA


2 Icahn School of Medicine at Mount Sinai, New York, NY, USA


Background


Definition of disease



  • Delirium is a syndrome characterized by a disturbance in attention and awareness; associated with a change in cognition that is not better accounted for by a pre‐existing, established, or evolving dementia. The disturbance develops over a short period (usually hours to days) and tends to fluctuate during the course of the day (DSM‐5).
  • Delirium may also be divided into subtypes based on the pattern of symptoms: hyperactive, hypoactive, and mixed:

    • Patients with hyperactive delirium demonstrate features of restlessness, agitation, and often experience hallucinations and delusions.
    • Patients with hypoactive delirium present with lethargy and reduced spontaneity, and show little spontaneous movement.
    • A mixed presentation may include features of both hyperactive and hypoactive delirium.

Incidence/prevalence



  • Delirium occurs in approximately 20–50% of general hospital inpatients, and 40–80% of patients admitted to the ICU.
  • Delirium is more common in patients who are elderly and have cognitive impairment.

Etiology


Common triggers of delirium include, among many others:



  • An underlying systemic infection or decompensated medical condition.
  • Drug exposure or withdrawal.
  • Pain.
  • Sleep deprivation.
  • Metabolic and electrolyte disturbances.

Pathophysiology


There have been multiple mechanisms proposed to explain the pathophysiology of delirium. Neurotransmitter dysfunction appears to play a role; namely decreased cholinergic activity, as well as serotonin imbalance. An abnormal central nervous system response to inflammatory mediators, including increased microglial activation, may also contribute to delirium.


Prevention


Important risk factors for delirium










Unmodifiable risk factors Potentially preventable risk factors
Advanced age
Apolipoprotein E4 genotype
History of hypertension
Alcohol use
Tobacco use
Pre‐existing cognitive impairment
History of depression
High severity of illness
Need for mechanical ventilation
Elevated inflammatory markers
High LNAA (large neutral amino acid) metabolite levels
Isolation
Need for multiple infusing medications 		Hearing/vision impairment (glasses, hearing aids)
Electrolyte abnormalities
Anemia
Fever
Lack of visitors
Inadequate pain management
Sedatives
Immobility
Catheters
Gastric tubes
Sleep deprivation
Dehydration
Inadequate light
Lack of BIS‐guided anesthesia

Diagnosis


Typical presentation



  • An elderly man with a history of mild dementia is admitted to the ICU after spine surgery. On postoperative day 2, he appears more confused than usual and is combative with the nursing staff.

Validated tools to aid in the diagnosis of delirium



  • Delirium is often unrecognized in critically ill patients without the use of an instrument to aid in the diagnosis.
  • Multiple validated tools exist to assess delirium in critically ill patients (Table 26.1).

    Table 26.1 Screening tools for delirium.
































    Screening tool Method Diagnostic criteria
    Confusion Assessment Method for the ICU (CAM‐ICU) Feature 1: assess for acute change in mental status, fluctuating behavior or serial Glasgow Coma Scale (GCS) score or sedation ratings over 24 hours
    Feature 2: assess using picture recognition or random letter test
    Feature 3: assess by asking the patient to hold up a certain number of fingers
    Feature 4: rate level of consciousness from alert to coma    		 Features 1 or 2 are positive, along with either feature 3 or feature 4
    Intensive Care Delirium Screening Checklist (ICDSC) Checklist of eight items:

    • Altered level of consciousness
    • Inattention
    • Disorientation
    • Hallucination or delusion
    • Psychomotor agitation or retardation
    • Inappropriate mood or speech
    • Sleep/wake cycle disturbance
    • Symptom fluctuation
    		Positive if score is ≥4
    Abbreviated Cognitive Test for Delirium (aCTD) Total score obtained by summing up two content scores: attention (range 0–14) and memory (range 0–10)
    Attention is assessed using the visual memory span subtest of the Wechsler Memory Scale Revised
    Memory is assessed by recognition of pictured objects    		 Positive if score is <11
    Neelon and Champagne Confusion Scale (NEECHAM) The scale is divided into three subscales:

    • Information processing (attention, processing, orientation)
    • Behavior (appearance, motor and verbal behavior)
    • Physiologic condition (vital function, oxygen saturation, urinary incontinence)
    		Moderate–severe: 0–19
    Mild: 20–24
    High risk: 25–26
    No delirium: >26
    (Scale out of 30)
    Delirium Detection Score (DDS) Checklist of eight items:

    • Agitation
    • Anxiety
    • Hallucination
    • Orientation
    • Seizures
    • Tremor
    • Paroxysmal sweating
    • Altered sleep–wake rhythm
    		Positive if score is >7
    Nursing Delirium Screening Scale Checklist of five items:

    • Disorientation
    • Inappropriate behavior
    • Inappropriate communication
    • Illusions/hallucinations
    • Psychomotor retardation
    		Positive if score is >1

  • Regardless of the screening tool utilized, it is important foremost to screen for delirium in the ICU.
  • Sensitivities for these screening tools vary related to different levels of training and experience amongst assessors, as well as heterogeneity of patient populations.
  • When delirium screening is applied, clinical benefits that may ensue include shorter duration of mechanical ventilation, shorter LOS, and lower mortality.
  • Similarly, a screening protocol for delirium is associated with significant cost savings.

Evaluation


Delirium may be a manifestation of a reversible medical problem. It is important to identify and treat possible medical and neurologic causes of delirium.


Common triggers of delirium



  • Hypoxia, hypercarbia.
  • Hypoglycemia, hyperglycemia.
  • Electrolyte disorders, acid–base disorders.
  • Sepsis.
  • Renal failure.
  • Liver failure.
  • Infection.
  • Intoxication.
  • Drug withdrawal.
  • Medication side effects.
  • Hemodynamic instability.
  • Stroke.
  • Seizure.
  • Encephalitis.
  • Posterior reversible encephalopathy syndrome.

Laboratory diagnosis


Although various markers have been correlated to delirium, no laboratory test has been found to be useful as a diagnostic test.


Potential pitfalls/common errors made regarding diagnosis of disease



  • Suboptimal use of preventive measures, which are essential to reduce the occurrence of delirium.
  • Lack of awareness and early use of screening tools for the diagnosis of delirium.
  • Failure to adequately review medications and differential diagnosis for medical causes of delirium.

Treatment and management


Treatment rationale



  • Delirium is best avoided by early measures targeted at prevention.
  • Prevention and supportive management includes mobilization, removal of catheters, and pain control.
  • Adequate analgesia is essential, as is judicious use of sedation.
  • Weaning from mechanical ventilation should be pursued early and aggressively as deemed medically safe.
  • Geriatric consultation may be beneficial in the management of elderly patients with multiple comorbidities and complex medication regimens.

Medications



  • Melatonin may assist with sleep regulation.
  • Benzodiazepines are useful in alcohol withdrawal, although in general it is best to avoid benzodiazepines as they may worsen delirium.
  • Haloperidol (<3.5 mg/day), risperidone (0.5–3 mg/day), and olanzapine (2.5–12.5 mg/day) are equally effective in treating delirium, with few adverse effects. Care should be taken to monitor QTC interval with electrocardiograms in patients treated with these agents.

Dexmedetomidine


Use of Dexmedetomidine (0.4–1.4 μg/kg/h) resulted in more ventilator‐free days in agitated delirium, and is useful as a rescue drug for agitation in non‐intubated patients in whom haloperidol has failed.



  • Dexmedetomidine in liver transplant recipients with postoperative delirium decreased ICU length of stay and the dose of supplemental midazolam as compared with haloperidol.
  • Dexmedetomidine is associated with bradycardia and hypotension.

Management/treatment algorithm (Algorithm 26.1)


Algorithm 26.1 Management of delirium in the ICU

Schematic illustration of the management of delirium in the ICU.

Specific populations


Pregnancy



  • Medications are considered adjunctive. Should pharmacologic treatment be deemed necessary, medications should be used with caution.
  • Haloperidol is pregnancy category C. Dexmedetomidine does not appear to cross the placental barrier, although data are limited.

Prognosis



  • Delirium is associated with multiple complications and adverse outcomes including self‐extubation and removal of catheters.
  • Delirium contributes to a prolonged hospital and intensive care length of stay, as well as increased mechanical ventilation duration.
  • Mortality risk is 2–3 times higher for critically ill patients who develop delirium.
  • Studies have linked delirium to development of cognitive impairment after hospital discharge.

Reading list



  1. Cavallazzi R, Saad M, Marik PE. Delirium in the ICU: an overview. Ann Intensive Care 2012; 2:49.
  2. Devlin JW, et al. Delirium assessment in the critically ill. Intensive Care Med 2007; 33(6):929–40.
  3. Inouye SK, et al. A multicomponent intervention to prevent delirium in hospitalized older patients. N Engl J Med 1999; 340:669–76.
  4. Page V, Ely EW. Delirium in Critical Care. UK: Cambridge University Press, 2011.
  5. Pun BT, Ely EW. The importance of diagnosing and managing ICU delirium. Chest 2007; 132(2):624–36.
  6. Stevens R, Sharshar T, Ely EW. Brain Disorders in Critical Illness. UK: Cambridge University Press, 2013.

Suggested websites


www.icudelirium.org


Guidelines


National society guidelines




















Title Source Date and weblink
Clinical Practice Guidelines for the Management of Pain, Agitation, and Delirium in Adult Patients in the Intensive Care Unit Society of Critical Care Medicine (SCCM) 2018
https://www.sccm.org/ICULiberation/Guidelines
Practice Guideline for the Treatment of Patients With Delirium American Psychiatric Association (APA) 2010
https://psychiatryonline.org
Delirium: prevention, diagnosis and management. Clinical guidelines [CG103] National Institute for Health and Clinical Excellence (NICE) 2010
https://www.nice.org.uk/guidance/cg103

International society guidelines
















Title Source Date
Evidence and Consensus Based Guideline for the Management of Delirium, Analgesia, and Sedation in Intensive Care Medicine. Revision 2015 DAS Taskforce, multidisciplinary Germany 2015
National Clinical Guideline Centre (UK) Delirium: Diagnosis, Prevention and Management Royal College of Physicians 2010

Evidence
























Type of evidence Comment Date and reference
Meta‐analysis Cochrane review of various antipsychotics for management of delirium 2007
Lonergan E, et al. Antipsychotics for delirium. Cochrane Database Syst Rev 2007;2:CD005594
Double‐blind RCT JAMA double‐blind RCT comparing dexmedetomidine and lorazepam in management of delirium in mechanically ventilated patients. Dexmedetomidine appeared superior, with more days alive without delirium and more time at target level of sedation 2007
Pandharipande PP, et al. Effect of sedation with dexmedetomidine vs lorazepam on acute brain dysfunction in mechanically ventilated patients: the MENDS randomized controlled trial. JAMA 2007;298(22):2644–53
Prospective cohort Cohort study validating use of CAM‐ICU as a screening tool to accurately diagnose delirium in critically ill patients who are often non‐verbal due to mechanical ventilation 2001
Ely EW, et al. Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM‐ICU). Crit Care Med 2001;29(7):1370–9
Review NEJM review article addressing the relationship between pain management, sedation, and delirium in the ICU 2014
Reade MC, Finfer S. Sedation and delirium in the intensive care unit. N Engl J Med 2014;370:444–54
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Nov 20, 2022 | Posted by in ANESTHESIA | Comments Off on 26: Delirium

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