Posted on August 5, 2008 in by admin20 Comments »

Diagnosing delirium

Delirium is an acute confusional state characterised by fluctuating mental status, inattention, and either disorganized thinking or altered level of consciousness. (See Table 1.)

Hippocrates described delirium as a fatal sign and described even then agitated and lethargic variants.

It’s all delirium

In the UK there have been any number of synonyms in use for delirium in critical care including ICU psychosis, ICU syndrome, acute confusional state, acute brain failure, septic encephalopathy, acute brain dysfunction as well as the exotic sounding sun downing. These are all delirium. It has been thought to be of little consequence, far from true.

There is hypoactive and hyperactive delirium

Delirium is a clinical syndrome and a bedside diagnosis. An acute change in mental status usually temporary it is always triggered by something be it a new infection, drug induced etc. The number one feature is an inability to maintain attention. Patients who can pay attention – squeezing on the right letters in a short sequence – are not delirious. The delirious patient is unable to organise their thoughts – figure out the answers to simple questions. There is an altered level of consciousness, most commonly drowsiness.

Hypoactive delirium, a lethargic patient who cannot pay attention or organise thought is much more common than hyperactive delirium and associated with worse outcomes. Hypoactive delirium is not depression, lack of motivation or a benign residual drug effect it is delirium. To detect hypoactive delirium you need to screen for it.

Many patients will fluctuate not only in and out of delirium but in between hyperactive and hypoactive delirium.

Screen for delirium

There are 2 validated screening tools to detect delirium in critically ill patients, the CAM-ICU (see below), which is a confusion assessment method for Intensive Care, and the ICDSC (opens in new window) Intensive Care Delirium Screening Checklist.

To monitor your patient’s brain you will need to screen for delirium, no equipment is needed and it can take less than 2 minutes. We’ve prepared a short video demonstration of the CAM-ICU assessment method, which you can watch on YouTube, or play the embedded video below:

CAM-ICU Delirium Assessement Method



Altered mental status

Has the patient shown any sign of being other than completely “themselves”?


Ask the patient to squeeze your hand. They will need to be responsive to verbal stimulation and keep their eyes open.

Ask the patient to correctly identify the letter ‘A’ in 10 letter sequence by squeezing only when they hear the letter ‘A’. Suggested Sequence:


They are allowed 2 mistakes – squeezing on a non-A, not squeezing on a A. More than 2 mistakes (however many it does not matter) is inattention.

If they pass the inattention test they are not delirious, the test is now complete.

More than 2 mistakes proceed to look for disorganized thinking or decreased level of consciousness.

Disorganized thinking &/or Reduced level of consciousness

5 elements – 4 simple yes/no questions, one simple command.

Use Set A or Set B

Set A:

Will a stone float on water?

Are there fish in the sea?

Does 1 pound weigh more than 2?

Do you use a hammer to hit a nail?

Set B:

Will a leaf float on water?

Are there elephants in the sea?

Does 2 pounds weigh more than 1?

Do you use a saw to hit a nail?

Ask the patient to “raise 2 fingers with one hand” and then to “do the same with the other hand” (do not instruct the patient to “raise 2 fingers” a second time, but instead instruct them to “do the same with the other hand”) .

They are allowed one mistake – one question wrong or unable to do the command. Two mistakes means disorganized thinking. The patient is CAM-ICU positive.

Come again?

Inattention plus altered conscious level equals delirium.

Inattention plus disorganized thinking equals delirium.

Inattention plus altered conscious level plus disorganized thinking equals delirium.

Resources for implementation: