Chapter
44
799
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.
Aroused &
Aroused &
Unaroused &
Aware
Unaware
Unaware
Anxiety
Delirium
Coma
Lethargy
Dementia
Brain Death
Locked-In State
Psychosis
Vegetative State
Table 44.1
Altered States of Consciousness
