Confusion Assessment Method for the ICU (CAM-ICU)
The CAM-ICU should be used daily on all patients admitted to the ICU even if they are mechanically ventilated.
- Delirium has been shown to be associated with worse outcomes in critically ill patients. It remains underdiagnosed given its sometimes subtle presentation.
- The CAM-ICU score is a validated and commonly used score to help monitor patients for the development or resolution of delirium.
- It is an adaptation of the Confusion Assessment Method (CAM) score for use in ICU patients.
- Since the first step of the score consists of identifying an “acute change from mental status baseline”, it may be difficult to use in patients in whom the neurologic baseline is unknown.
- If a patient’s neurologic baseline changes during the course of his hospitalization (such as a new CVA for example), then the new baseline should be used for any new assessment.
- In order for the CAM-ICU score to be accurate, patients should not be sedated, or have a RASS of 0.
- Delirium affects up to 89% of ICU patients and has been shown to result in higher mortality. The relative risk of death increases for each day the patient remains delirious. Prompt recognition of this condition is therefore important.
- To this day delirium remains a clinical diagnosis. Few clinical tools have been demonstrated to be useful in helping identify the presence or absence of delirium.
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- When applied, the CAM-ICU will provide a qualitative result of “delirium present” or “delirium absent”.
- Patients identified as suffering from delirium will be investigated and managed accordingly.
- The CAM-ICU should continue to be used daily even in patients that are delirious in order to monitor for resolution of the condition.
- The management of delirium is an extensive topic that is beyond the scope of this discussion.
- Screen all ICU patients daily for delirium using a validated clinical tool such as the CAM-ICU.
- The screening is best performed by individuals trained in the proper usage of this method such as ICU nurses.
Algorithm of Yes/No questions.
Facts & Figures
The patient is CAM-ICU positive (patient has delirium) if:
- RASS ≥ -3, AND
- Acute onset change in mental status or fluctuating course in mental status, AND
- >2 Errors in letters attention test, AND
- Either RASS is not 0, OR >1 Error to questions and commands.
For more information and a schematic of questions, see this CAM-ICU training manual.
- The Confusion Assessment Method (CAM) was originally derived in 56 general ward patients. and found to have high sensitivity and specificity for the diagnosis of delirium by non-psychiatrists.
- The CAM was later modified for use in the intensive care unit and renamed CAM-ICU. This modified score was tested in 38 intensive care unit patients by nurses and intensivists and found to have up to 100% sensitivity and 93% specificity for the diagnosis of delirium.
- In order to validate the CAM-ICU in mechanically ventilated patients, Ely, et al. prospectively enrolled 111 patients, 96 of which were included in the final analysis. The evaluations were made by two critical care nurses. The CAM-ICU was showed to have up to 100% sensitivity and specificity, as well as high inter-rater reliability in this patient population.
- Systematic Review and Meta-Analysis of clinical tools for diagnosis of delirium in critically ill patients.
Original/Primary ReferenceInouye SK, van Dyck CH, Alessi CA, Balkin S, Siegal AP, Horwitz RI. Clarifying confusion: the confusion assessment method. A new method for detection of delirium. Ann Intern Med. 1990;113(12):941–948.
ValidationEly EW, Margolin R, 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 Jul;29(7):1370-9.
Other ReferencesEly EW, Inouye SK, et. al. Delirium in mechanically ventilated patients: validity and reliability of the confusion assessment method for the intensive care unit (CAM-ICU).JAMA. 2001 Dec 5;286(21):2703-10.Gusmao-Flores D, Salluh JIF, Chalhub RÁ, Quarantini LC. The confusion assessment method for the intensive care unit (CAM-ICU) and intensive care delirium screening checklist (ICDSC) for the diagnosis of delirium: a systematic review and meta-analysis of clinical studies. Crit Care. 2012;16(4):R115.Ely EW, and Vanderbilt University. Confusion Assessment Method for the ICU (CAM-ICU). The Complete Training Manual. Revised 2014.
About the Creator
Sharon K. Inouye, MD, MPH, is director of the Aging Brain Center and a professor of medicine at Harvard Medical School and Beth Israel Deaconess Medical Center. She received her medical degree at University of California San Francisco, and her MPH from Yale University. Her research focuses on delirium and functional decline in hospitalized older patients, resulting in more than 200 peer-reviewed original articles.
To view Dr. Sharon K. Inouye's publications, visit PubMed