Delirium: Assess, Prevent and Manage

The D component of the ABCDEF Bundle refers to assessing, preventing and managing delirium.

Delirium is experienced by 50%–80% of mechanically ventilated patients and 20%–50% of patients with illness of lower severity, resulting in prolonged hospitalization, increased mortality and increased cost. Long-term effects on the patient include increased risk of mortality and long-term cognitive impairment.

Delirium is identified by the following key features:

  • Disturbance in attention and awareness
  • Disturbance in cognition (e.g., memory, disorientation, language, and perception)
  • Development over a short period of time and tendency to fluctuate during the day
  • Disturbance not better explained by a preexisting, established or evolving neurocognitive disorder, and not occurring in the context of a severely reduced level of arousal such as coma
  • Evidence from patient’s history, physical examination and/or laboratory results that the disturbance is caused by a medical condition, substance intoxication or withdrawal, or medication/toxin side effect

  • Associated but nondiagnostic symptoms of ICU delirium include:
  • Hallucinations and delusions
  • Abnormal psychometric activity (e.g., agitation or lethargy)
  • Emotional disturbances (e.g., fear, anger, depression or apathy)
  • Sleep disturbances
Drugs have the potential for contributing to delirium. The ABCDEF bundle suggests the following approach to delirium management:
  • Stop (consider sedatives, review medications and plan to reduce drug exposure)
  • THINK (Toxic situations, Hypoxemia, Infection/nosocomial sepsis, Immobilization, Nonpharmacologic interventions, K+ or other electrolyte disturbances)
  • Medicate (guideline suggests nonbenzodiazepine sedatives)

Integration of the pain, agitation and delirium (PAD) guidelines and/or the ABCDEF bundle, along with specific delirium prevention strategies leads to a statistically lower mortality and shorter ICU length of stay, along with a static delirium incidence.

Implementation Tools
Implementing the D component of the ABCDEF bundle




PAD Delirium Assessment Recommendations

Routinely monitor for delirium in all adult ICU patients.

Use either:

  • Confusion Assessment Method for the ICU (CAM-ICU)
  • Intensive Care Delirium Screening Checklist (ICDSC)

Tools for Delirium Assessment

The Confusion Assessment Method for the ICU (CAM-ICU) and the Intensive Care Delirium Screening Checklist (ICDSC) are the most valid and reliable delirium monitoring tools for adult ICU patients.

CAM-ICU Assessment Tool

CAM-ICU Flowsheet

CAM-ICU Training Manual (Frequently Asked Questions for Putting the CAM-ICU into Practice, pages 16-20) 

Intensive Care Delirium Screening Checklist (ICDSC)


Implementing Delirium Screening in the ICU: Secrets to Success
Crit Care Med. 2013 Sep.


 Additional Reading


Balas MC, Vasilevskis EA, Olsen KM, et al. Effectiveness and safety of the awakening and breathing coordination, delirium monitoring/management, and early exercise/mobility bundle. Crit Care Med. 2014 May;42(5):1024-1036.

Kamdar BB, King LM, Collop NA, et al. The effect of a quality improvement intervention on perceived sleep quality and cognition in a medical ICU. Crit Care Med. 2013 Mar;41(3):800-809.

Colombo R, Corona A, Praga F, et al. A reorientation strategy for reducing delirium in the critically ill: results of an interventional study. Minerva Anestesiol. 2012 Sep;78(9):1026-1033.

Gusmao-Flores D, Salluh JI, Chalhub RÁ, Quartini 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 Jul;16(4):R115.

Shehabi Y, Riker RR, Bokesch PM, Wisemandle W, Shintani A, Ely EW; SEDCOM Study Group. Delirium duration and mortality in lightly sedated, mechanically ventilated intensive care patients. Crit Care Med. 2010 Dec;38(12):2311-2318.

Needham DM, Korupolu R, Zanni JM, et al. Early physical medicine and rehabilitation for patients with acute respiratory failure: a quality improvement project. Arch Phys Med Rehabil. 2010 Apr;91(4):536-542.

Pisani MA, Kong SY, Kasl SV, et al. Days of delirium are associated with 1-year mortality in an older intensive care unit population. Am J Respir Crit Care Med. 2009 Dec;180(11):1092-1097.

Schweickert WD, Pohlman MC, Pohlman AS, et al. Early physical and occupational therapy in mechanically ventilated, critically ill patients: a randomized controlled trial. Lancet. 2009 May;373(9678):1874-1882.

Ely EW, Shintani A, Truman B, et al. Delirium as a predictor of mortality in mechanically ventilated patients in the intensive care unit. JAMA. 2004 Apr;291(14):1753-1762.

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 Dec;286(17):2703-2710.

Ely EW, Gautam S, Margolin R, et al. The impact of delirium in the intensive care unit on hospital length of stay. Intensive Care Med. 2001 Dec;27(12):1892-1900.

Dubois MJ, Bergeron N, Dumont M, Dial S, Skrobik Y. Delirium in an intensive care unit: a study of risk factors. Intensive Care Med. 2001 Aug;27(8):1297-1304.

Bergeron N, Dubois MJ, Dumont M, et al. Intensive Care Delirium Screening Checklist: evaluation of a new screening tool. Intensive Care Med. 2001 May;27(5):859-864.