Terminology & Mnemonics

Over 25 different terms have been used to describe the spectrum of cognitive impairment in the ICU including: ICU psychosis, ICU syndrome, acute confusional state, septic encephalopathy and acute brain failure. The Diagnostic and Statistical Manual of Mental Disorders (DSM IV) officially defines delirium as a disturbance of consciousness with inattention accompanied by a change in cognition or perceptual disturbance that develops over a short period of time (hours to days) and fluctuates over time.

The three motoric subtypes of delirium are hyperactive, hypoactive, and mixed. Medical and nursing literature often refers to patients with hyperactive delirium as having ICU psychosis. The neurology literature generally uses the term “delirium” to refer almost exclusively to hyperactive patients and “acute encephalopathy” as a synonym for hypoactive delirium. We recognize that patients in the ICU develop the spectrum of 3 delirious states (hyper, hypo, and mixed). For general purposes within this web site, we will use the term “delirium” to indicate the spectrum of these states and will make distinctions between these motoric subtypes whenever possible with regard to etiology, clinical outcome, and treatment.


What to THINK about when delirium is present

  • T
    Toxic Situations
    CHF, shock, dehydration
    Deliriogenic meds (Tight Titration)
    New organ failure, e.g, liver, kidney
  • H
  • I
    Infection/sepsis (nosocomial), Immobilization
  • N
    Nonpharmacological interventions
    Hearing aids, glasses, reorient, sleep protocols, music, noise control, ambulation
  • K
    K+ or Electrolyte problems
* Adapted with permission from: Marta Render, MD – Veteran Affairs In-patient Evaluation Center (IPEC)

Dr. DRE (Disease remediation, Drug Removal, Environmental modifications)

Strategies to consider when delirium is present

  • Dr
    Diseases (Sepsis, COPD, CHF)
  • DR
    Drug Removal (SATs and stopping benzodiazepines/ narcotics)
  • E
    Environment (Immobilization, sleep and day/night, hearing aids, glasses)


Differential diagnosis for patients with Delirium
(Remember: delirium usually has more than one cause)

  • D
  • E
    Eyes, ears, and other sensory deficits
  • L
    Low O2 states (e.g. heart attack, stroke, and pulmonary embolism)
  • I
  • R
    Retention (of urine or stool)
  • I
    Ictal state
  • U
  • M
    K+ or ElectrMetabolic causes (DM, Post-operative state, Sodium abnormalities)olyte problems
  • (S)
    Subdural hematoma
* Adapted from: Saint Louis University Geriatrics Evaluation Mnemonics Screening Tools (SLU GEMS). Developed or compiled by: Faculty from Saint Louis University Geriatrics Division and St. Louis Veterans Affairs GRECC.


  • D
    Drugs (continuous drips, Na+, Ca+, BUN/Cr, NH3+)
  • E
    Environmental factors (hearing aids, eye glasses, sleep/wake cycle)
  • L
    Labs (including Na+, K+, Ca+, BUN/Cr, NH3+)
  • I
  • R
    Respiratory status (ABGs-PaO2 and PCO2)
  • I
  • O
    Organ failure (renal failure, liver failure, heart failure)
  • U
    Unrecognized dementia
  • S
    Shock (sepsis, cardiogenic)/Steroid


Mnemonic for risk factors and causes of ICU DELIRIUM(S)

  • Iatrogenic exposure
    Consider any diagnostic procedure or therapeutic intervention or any harmful occurrence that was not a natural consequence of the patient’s illness
  • Cognitive impairment
    Preexisting dementia, or MCI or depression
  • Use of restraints and catheters
    Reevaluate the use of restraints and bladder catheters daily
  • Drugs
    Evaluate the use of sedatives (e.g. benzodiazepines or opiates) and medications with anticholinergic activity.
    Consider the abrupt cessation of smoking or alcohol.
    Consider withdrawal from chronically used sedatives.
  • Elderly
    Evaluate patients older than 65 years with greater attention
  • Laboratory abnormalities
    Especially hyponatremia, azotemia, hyperbilirubinemia, hypocalcemia and metabolic acidosis
  • Infection
    Sepsis and severe sepsis.
    Especially urinary, respiratory tract infections.
  • Respiratory
    Consider respiratory failure (PCO2 greater than 45 mmHg or PO2 less than 55 mmHg or oxygen saturation less than 88%).
    Consider causes such as COPD, ARDS, PE*
  • Intracranial perfusion
    Consider presence of hypertension or hypotension.
    Consider hemorrhage, stroke, tumor
  • Urinary/faecal retention
    Consider urinary retention or fecal impaction, especially in elderly and in postoperative patients
  • Myocardial
    Consider myocardial causes: myocardial infarction, acute heart failure, arrhythmia
  • Sleep and Sensory deprivation
    Consider the alterations of the sleep cycle and sleep deprivation.
    Consider the non availability of glasses (poor vision).
    Consider the non availability of hearings devices (poor hearing).


Differential Diagnosis of Delirium.

  • Infection
    HIV, sepsis, Pneumonia
  • Withdrawal
    Alcohol, barbiturate, sedative-hypnotic
  • Acute metabolic
    Acidosis, alkalosis, electrolyte disturbance, hepatic failure, renal failure
  • Trauma
    Closed-head injury, heat stroke, postoperative, severe burns
  • CNS pathology
    Abscess, hemorrhage, hydrocephalus, subdural hematoma, Infection, seizures, stroke, tumors, metastases, vasculitis, Encephalitis, meningitis, syphilis
  • Hypoxia
    Anemia, carbon monoxide poisoning, hypotension, Pulmonary or cardiac failure
  • Deficiencies
    Vitamin B12, folate, niacin, thiamine
  • Endocrinopathies
    Hyper / hypoadrenocorticism, hyper / hypoglycemia, Myxedema, hyperparathyroidism
  • Acute vascular
    Hypertensive encephalopathy, stroke, arrhythmia, shock
  • Toxins or drugs
    Prescription drugs, illicit drugs, pesticides, solvents
  • Heavy Metals
    Lead, manganese, mercury


Differentiating Delirium from Dementia

  • Delirium
  • Consciousness
    Decreased or hyper alert
  • Orientation
  • Course
    Steady slow decline
  • Onset
    Acute or sub acute
  • Attention
    Usually normal
  • Psychomotor
    Agitated or lethargic
    Usually normal
  • Hallucinations
    Perceptual disturbances
    May have hallucinations
    Usually not present
  • Sleep-wake-cycle
    Usually normal
  • Speech
    Slow, incoherent
    Aphasic, anomic difficulty finding words
*Adapted from: Saint Louis University Geriatrics Evaluation Mnemonics Screening Tools (SLU GEMS). Developed or compiled by: Faculty from Saint Louis University Geriatrics Division and St. Louis Veterans Affairs GRECC.

Understanding international differences in terminology for delirium and other types of acute brain dysfunction in critically ill patients.

Morandi A1, Pandharipande P, Trabucchi M, Rozzini R, Mistraletti G, Trompeo AC, Gregoretti C, Gattinoni L, Ranieri MV, Brochard L, Annane D, Putensen C, Guenther U, Fuentes P, Tobar E, Anzueto AR, Esteban A, Skrobik Y, Salluh JI, Soares M, Granja C, Stubhaug A, de Rooij SE, Ely EW.


Background: Delirium (acute brain dysfunction) is a potentially life threatening disturbance in brain function that frequently occurs in critically ill patients. While this area of brain dysfunction in critical care is rapidly advancing, striking limitations in use of terminology related to delirium internationally are hindering cross-talk and collaborative research. In the English literature, synonyms of delirium such as the Intensive Care Unit syndrome, acute brain dysfunction, acute brain failure, psychosis, confusion, and encephalopathy are widely used. This often leads to scientific ‘‘confusion’’ regarding published data and methodology within studies, which is further exacerbated by organizational, cultural and language barriers.

Objective: We undertook this multinational effort to identify conflicts in terminology and phenomenology of delirium to facilitate communication across medical disciplines and languages.

Methods: The evaluation of the terminology used for acute brain dysfunction was determined conducting communications with 24 authors from academic communities throughout countries/regions that speak the 13 variants of the Romanic languages included into this manuscript.

Results: In the 13 languages utilizing Romanic characters, included in this report, we identified the following terms used to define major types of acute brain dysfunction: coma, delirium, delirio, delirium tremens, délire, confusion mentale, delir, delier, Durchgangs-Syndrom, acute verwardheid, intensivpsykose, IVA-psykos, IVA-syndrom, akutt konfusion/ forvirring. Interestingly two terms are very consistent: 100%of the selected languages use the term coma or koma to describe patients unresponsive to verbal and/or physical stimuli, and 100% use delirium tremens to define delirium due to alcohol withdrawal. Conversely, only 54% use the term delirium to indicate the disorder as defined by the DSM-IV as an acute change in mental status, inattention, disorganized thinking and altered level of consciousness. Conclusions: Attempts towards standardization in terminology, or at least awareness of differences across languages and specialties, will help cross-talk among clinicians and researchers.

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