CAM-ICU Delirium Assessment — Confusion Assessment Method for the ICU
The Confusion Assessment Method for the ICU (CAM-ICU) is a validated, rapid bedside assessment tool for detecting delirium in critically ill patients, using a 4-feature algorithm to determine the presence or absence of delirium.
About
The CAM-ICU was developed by Ely et al. and validated in a landmark study published in JAMA in 2001. It adapted the original Confusion Assessment Method (CAM) for use in non-verbal, mechanically ventilated ICU patients. The CAM-ICU assesses four features of delirium: (1) Acute onset or fluctuating course of mental status, (2) Inattention (as assessed by the Attention Screening Exam or picture recognition), (3) Disorganized thinking, and (4) Altered level of consciousness (using the Richmond Agitation-Sedation Scale — RASS). Delirium is diagnosed if Features 1 and 2 are present, plus either Feature 3 or Feature 4. The CAM-ICU has a sensitivity of 73-100% and specificity of 89-100% for the diagnosis of delirium compared to DSM-IV criteria. It requires 1-2 minutes to complete and can be administered by any trained healthcare provider. Delirium is independently associated with increased mortality, prolonged mechanical ventilation, longer ICU stay, and long-term cognitive impairment.
Formula
CAM-ICU Positive = Feature 1 (Acute Onset/Fluctuating) AND Feature 2 (Inattention) AND (Feature 3 (Disorganized Thinking) OR Feature 4 (Altered LOC))
The CAM-ICU algorithm requires the presence of Feature 1 (acute onset of mental status changes or fluctuating course over the past 24 hours) AND Feature 2 (inattention as shown by difficulty following commands or abnormal Attention Screening Exam score) AND either Feature 3 (disorganized thinking with rambling or irrelevant conversation) or Feature 4 (altered level of consciousness — anything other than alert/calm on RASS). All four features can be assessed rapidly at the bedside. If the patient is deeply sedated or unarousable (RASS -4 or -5), the assessment should be deferred. Reassessment should occur regularly (every shift or daily) as delirium can fluctuate.
Score Interpretation
Delirium is a common and serious complication in ICU patients, affecting 20-80% of patients depending on severity of illness. The CAM-ICU is recommended by the Society of Critical Care Medicine (SCCM) PADIS Guidelines for routine delirium monitoring in all ICU patients. Delirium is independently associated with a 2-3x increase in hospital mortality, prolonged mechanical ventilation (mean 4-6 additional days), prolonged ICU and hospital length of stay, increased costs ($4,000-$17,000 per patient), and long-term cognitive impairment comparable to mild Alzheimer's disease. The CAM-ICU has been validated in >1,000 patients across multiple ICUs and translated into >20 languages. It takes 1-2 minutes to administer and can be performed by nurses, physicians, respiratory therapists, and other healthcare professionals with minimal training. Regular delirium screening with CAM-ICU is associated with improved delirium detection rates (from <30% to >90%) and better clinical outcomes.
CAM-ICU Negative — No Delirium — 0–0
Features 1 and 2 not both present, or neither Feature 3 nor Feature 4 present. Delirium not detected at this time.
Management: Continue routine delirium screening per ICU protocol (every shift/daily). Maintain prevention measures: early mobilization, sleep hygiene, sensory optimization, family involvement.
CAM-ICU Positive — Delirium Present — 1–1
Features 1 AND 2 AND (3 OR 4) present. Delirium is diagnosed according to CAM-ICU criteria.
Management: Identify and treat underlying cause (infection, metabolic, medication, CNS, withdrawal). Perform medication review — stop deliriogenic medications (anticholinergics, benzodiazepines, corticosteroids). Non-pharmacologic bundle: reorientation, family presence, sleep protocol, early mobility, hearing/vision aids. Consider pharmacologic management if agitated and unsafe (low-dose haloperidol 1-2 mg IV/IM q4h PRN or atypical antipsychotic). Avoid benzodiazepines unless for alcohol/sedative withdrawal.
Reference Ranges
| Population | Normal Range | Notes |
|---|---|---|
| ICU patients (intubated and non-intubated) | Negative / Positive | Negative = no delirium. Positive = delirium present. Reassess every shift or daily. |
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View medical review board & editorial policy →Example Calculation
An 82-year-old man is 3 days post-emergent laparotomy for perforated duodenal ulcer, mechanically ventilated. He has a history of hypertension and mild dementia. The bedside nurse assesses CAM-ICU: Feature 1 (Acute onset/fluctuating): Over the past 24 hours, the patient was alert and following commands during the day but became confused and agitated at night. Positive. Feature 2 (Inattention): Patient is unable to complete the Attention Screening Exam correctly — misses 4 of 5 pictures in the recognition test. Positive. Feature 3 (Disorganized Thinking): Patient is unable to answer simple yes/no questions correctly ("will a stone float on water?"), and his speech is rambling and disjointed. Positive. Feature 4 (Altered LOC): RASS score fluctuates from +2 (agitated) to -1 (drowsy) over the day — not consistently alert/calm. Positive. CAM-ICU: Feature 1 (+) AND Feature 2 (+) AND (Feature 3 (+) OR Feature 4 (+)) = Positive for delirium. Management: The medical team is notified. Laboratory workup reveals a urinary tract infection. Antibiotics are started, haloperidol 1 mg IV is given for severe agitation, non-pharmacologic measures are implemented (reorientation, family presence, sleep protocol, early mobilization in chair), and deliriogenic medications are reviewed (discontinue midazolam infusion, start dexmedetomidine for sedation). Regular reassessment every shift is ordered.
Related Conditions
Related Medications
Common Mistakes
Assessing CAM-ICU in deeply sedated or unarousable patients
If the patient has a RASS score of -4 (responsive only to physical stimulation) or -5 (unresponsive), the CAM-ICU assessment cannot be performed. Document the patient as "unable to assess" due to deep sedation and reassess when lighter sedation is achieved.
Confusing delirium with dementia in CAM-ICU assessment
Delirium has acute onset and fluctuating course (Feature 1) while dementia is chronic and progressive. CAM-ICU assesses for delirium superimposed on dementia. Assess Feature 1 carefully — ask family or review nursing notes for acute change from baseline. A patient with dementia can still have delirium.
Using CAM-ICU only once at admission
Delirium fluctuates and can develop at any point during ICU stay. CAM-ICU should be performed every shift (12-hourly) and whenever there is a change in mental status. Early detection of new-onset delirium allows prompt investigation and treatment.
Frequently Asked Questions
What is the difference between CAM-ICU and ICDSC?
Can CAM-ICU be used in non-intubated patients?
How often should CAM-ICU be performed?
References
- Ely EW, Inouye SK, Bernard GR, et al. Delirium in mechanically ventilated patients: validity and reliability of the confusion assessment method for the intensive care unit (CAM-ICU). JAMA. 2001;286(21):2703-2710. PubMed
- Barr J, Fraser GL, Puntillo K, et al. Clinical practice guidelines for the management of pain, agitation, and delirium in adult patients in the intensive care unit. Crit Care Med. 2013;41(1):263-306. PubMed
- Devlin JW, Skrobik Y, Gélinas C, et al. Clinical practice guidelines for the prevention and management of pain, agitation/sedation, delirium, immobility, and sleep disruption in adult patients in the ICU. Crit Care Med. 2018;46(9):e825-e873. PubMed