Understanding Coma
Coma is a prolonged period of
unconsciousness. Unconsciousness is the lack of
appreciation of (or reaction to) a stimulus. Coma differs from sleep in that one
cannot be aroused from a coma.
Coma involves two different concepts:
1.) Reactivity: Reactivity refers
to the innate (or inborn) functions of the brain, i.e., the telereceptors
(eyes and ears), the nociceptors (responses to pain), the arousal reaction
(wakefulness) and the orienting response (turning one's head toward the source
of sound or movement). We could also refer to these as reflexive
movements.
2.) Perceptivity: Perceptivity
refers to the responses of the nervous system to stimuli, which have been
learned or acquired, i.e., language, communication skills, individual methods
of movement such as gestures, etc. Perceptivity also refers to less complex
learned or acquired reactions such as flinching when threatened. We can also
think of these as conscious movements.
A person in a coma does not exhibit reactivity or
perceptivity. He/she can not be aroused by calling
his/her name or in response to pain.
As a person begins to emerge from a coma, they may begin to
react to certain stimuli. To regain "consciousness"
however, reactivity and perceptivity must both be present. These two elements
are necessary for a state of awareness. Often, many of the elements of
perceptivity must be relearned, such as speech, self-care, etc.
Many people are surprised that all stages of coma do not
resemble what we have been taught to expect; a deep sleep.
The person in the coma may exhibit movement, make sounds, and
experience agitation. It is important to keep in mind that the coma patient may
exhibit reflex activities which mimic conscious activities. Coma patients may be
restrained to keep them from removing tubes or dislodging IVs. The progress of
coma is measured by the patient's increasing awareness of external stimuli.
There are many levels of coma which the patient will pass through as
functionality increases.
Sometimes a coma is induced by chemical
means to aid in medical treatment and recovery.
It is very important to remember to speak positively to and
in the presence of the person in a coma. Some patients
claim to remember very distinctly events while they were in a coma. And although
we cannot be positive about the level of awareness in any particular case,
studies show that a positive attitude may be beneficial to the recovery of the
patient. Conversations about the possible negative outcomes with doctors,
nurses, and family should be conducted with discretion.
It is also important to keep in mind that
different injuries produce different outcomes. While we can expect that a
patient may slowly emerge over time, some patients can suffer from "locked in"
syndrome in which they are awake but unable to react or act upon their
environment, or recover to a point where they have limited capacities, or have a
limited recovery which will require long term care.
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