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First posted by Charles Gomersall November 2009

Patient classified as having delirium if has features 1 AND 2 AND either 3 OR 4

Feature 1. Acute Onset of Mental Status Changes or Fluctuating Course

  • Is there evidence of an acute change in mental status from the baseline?

  • Or has the (abnormal) behavior fluctuated during the past 24 hrs, that is, tended to come and go or increase and decrease in severity as evidenced by fluctuation in Glasgow Coma score or sedation score or by direct observation of patient?

Feature 2. Inattention

Does the patient have difficulty focusing attention as evidenced by score of <8 correct answers on picture recognition or vigilance A random letter test (neither of these tests require verbal response)?


Feature 3. Disorganized Thinking

  • Was the patient’s thinking disorganized or incoherent, such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject?

  • If the patient is unable to speak ask the following questions and ask the patient to respond to the following "commands":

    • Questions

      • Will a stone float on water?

      • Are there fish in the sea?

      • Can 1 pound weigh more than 2 pounds?

      • Can you use a hammer to pound a nail?

    • "Commands"

      • Are you having any unclear thinking?

      • Hold up this many fingers (examiner holds two fingers in front of the patient)

      • Now, do the same thing with the other hand (without holding up two fingers in front of the patient)

Feature 4. Altered Level of Consciousness

Any level of consciousness other than “alert.”

  • Alert—normal, spontaneously fully aware of environment and interacts appropriately

  • Vigilant—hyperalert

  • Lethargic—drowsy but easily aroused, unaware of some elements in the environment, or not spontaneously interacting appropriately with the interviewer; becomes fully aware and appropriately interactive when prodded minimally

  • Stupor—difficult to arouse, unaware of some or all elements in the environment, or not spontaneously interacting with the interviewer; becomes incompletely aware and inappropriately interactive when prodded strongly

  • Coma—unarousable, unaware of all elements in the environment, with no spontaneous interaction or awareness of the interviewer, so that the interview is difficult or impossible even with maximal prodding

Further reading

Ely EW 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; 29:1370-1379

©Charles Gomersall, April, 2014 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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