FAST FACT AND CONCEPT #160: Screening for ICU Delirium

Authors: Richard Altman, MD; Eric Milbrandt, MD, MPH; and Robert Arnold, MD

Delirium is an acute, fluctuating change in mental status, accompanied by sleep/wake cycle disruption, inattention, and altered perceptions (hallucinations/delusions) (see FF #1, 60). Delirium can be hypoactive or hyperactive. Patients with hypoactive delirium are calm, but inattentive and manifest decreased mobility. Patients with hyperactive delirium are agitated and combative, and also lack the ability to maintain attention to complete tasks. Delirium can be considered a marker of acute brain dysfunction, much like shock is evidence for dysfunction of the cardiovascular system 1.

Delirium occurring in the ICU is associated with an increased length of hospitalization, increased need for institutionalization, and higher short and long-term mortality 2. In the ICU, delirium occurs in as many as 80% of patients, but is often overlooked or misdiagnosed because of the difficulty of assessing mental states in intubated patients. Three assessment tools have been described in the literature to aid in delirium diagnosis.

1) The Confusion Assessment Method-Intensive Care Unit(CAM-ICU) Assessment Tool is the best documented method of diagnosing delirium in the ICU 3. This tool was specifically designed for use in non-verbal (i.e. mechanically ventilated) patients. With the CAM-ICU, delirium is diagnosed when patients demonstrate 1) an acute change in mental status or fluctuating changes in mental status, 2) inattention measured using either an auditory or visual test, and either 3) disorganized thinking, or 4) an altered level of consciousness. Importantly, the CAM-ICU can only be administered if the patient is arousable to voice without the need for physical stimulation. The CAM-ICU includes very specific assessment questions/tools, found online at icudelirium.org.

When administered by a nurse, the CAM-ICU takes only 1 to 2 minutes to conduct and has a minimum of 93% sensitivity and 89% specificity for detecting delirium as compared to full DSM-IV assessment by a geriatric psychiatrist 2, 4 National guidelines recommend routine use of the CAM-ICU for delirium assessment in all critically ill patients and treatment with haloperidol when delirium is present. 5 However, these recommendations are based on expert opinion and limited case series. It remains unknown whether diagnosis and/or treatment of delirium will lead to better patient outcomes. While there are some early observational cohort data suggesting that patients treated with haloperidol have lower hospital mortality, this finding needs confirmation in a randomized, controlled trial before being applied to routine patient care.

2) The Intensive Care Delirium Screening Checklist assesses eight features of delirium: altered level of consciousness, inattention, disorientation, hallucinations, psychomotor agitation/retardation, inappropriate mood/speech, sleep/wake cycle disturbance, and symptom fluctuation. The sensitivity and specificity of this tool were 99% and 64% respectively in one report. 6

3) The Delirium Screening Checklist is another recent tool that uses a checklist similar to the Intensive Care Delirium Screening Checklist 7.

Recommendation: It is believed that prompt recognition and treatmentof ICU deliriumis important for patient safety. Use of rapid tools such as CAM-ICU can help identify ICU delirium and are recommended when assessing mental status changes. The benefit of routine use of these screening tools is yet to be tested.

References

1. Ely EW, Siegel MD, Inouye SK. Delirium in the Intensive Care Unit: An Under-Recognized Syndrome of Organ Dysfunction. Seminars in Respiratory & Critical Care Medicine 2001; 22(2):115-126.
2. Ely EW, Inouye SK, Bernard GR, Gordon S, Francis J, May L, Truman B, Speroff T, Gautam S, Margolin R, Hart RP, Dittus R. 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.
3. Ely EW, Truman, B. The Confusion Assessment Method for the ICU (CAM-ICU) Training Manual, http://www.icudelirium.org/delirium/training-pages/CAM-ICU%20trainingman.2005.pdf, referenced April 18, 2006.
4. Ely EW, Margolin R, Francis J, May L, Truman B, Dittus R, Speroff T, Gautam S, Bernard GR, Inouye SK. Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Crit Care Med 2001; 29:1370-9.
5. Jacobi J, Fraser GL, Coursin DB, Riker RR, Fontaine D, Wittbrodt ET, Chalfin DB, Masica MF, Bjerke HS, Coplin WM, Crippen DW, Fuchs BD, Kelleher RM, Marik PE, Nasraway SA, Jr., Murray MJ, Peruzzi WT, Lumb PD. Clinical practice guidelines for the sustained use of sedatives and analgesics in the critically ill adult. Crit Care Med 2002; 30:119-41.
6. Bergeron N, Dubois MJ, Dumont M, Dial S, Skrobik Y. Intensive Care Delirium Screening Checklist: evaluation of a new screening tool. Intensive Care Med 2001; 27:859-864
7. Otter H, Martin J, Basell K, von Heymann C, Hein OV, Bollert P, Jansch P, Behnisch I, Wernecke KD, Konertz W, Loening S, Blohmer JU, Spies C. Validity and reliability of the DDS for severity of delirium in the ICU. Neurocrit Care 2005; 2(2):150-8.

Fast Facts were edited by David Weissman MD, Palliative Care Center, Medical College of Wisconsin until January 2007.  For comments/questions write to the current editor, Drew Rosielle MD: drosiell@mcw.edu. The complete set of Fast Facts is available at EPERC: www.eperc.mcw.edu

Copyright and Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Citation for referencing: Alman R, Millbrandt E, Arnold R. Screening for ICU Delirium; Fast Facts and Concepts #160. End-of-Life / Palliative Education Resource Center: www.eperc.mcw.edu.

Purpose: Self-Study Guide, Teaching

Audience(s)

ACGME Competencies: Medical Knowledge; Patient Care

Keyword(s): ICU

Specific Disease and Organ System Category(s): ICU