Marino The ICU Book 4e, IE

44

Chapter

DISORDERS OF CONSCIOUSNESS

I think, therefore I am.

René Descartes 1644

The ability to recognize and interact with the surroundings (i.e., con- sciousness) is the sina qua non of the life experience, and loss of this abil- ity is one of the dominant (and most prevalent) signs of a life-threatening illness. This chapter describes the principal disorders of consciousness encountered in the ICU, including delirium, coma, and the ultimate dis- order of consciousness, brain death. ALTERED CONSCIOUSNESS Consciousness has two components: arousal and awareness . 1. Arousal is the ability to experience your surroundings, and is also known as wakefulness . 2. Awareness is the ability to understand your relationship to your sur- roundings, and is also known as responsiveness . These two components are used to identify the altered states of con- sciousness in Table 44.1.

Table 44.1

Altered States of Consciousness

Aroused &

Aroused & Unaware

Unaroused &

Aware

Unaware

Anxiety

Delirium Dementia

Coma

Lethargy

Brain Death

Locked-In State

Psychosis Vegetative State

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