How to Approach an Unconscious Patient

Coma (from the Greek κώμα [ko̞ma], meaning deep sleep) is a
state of unconsciousness lasting more than 6 hours, in which a
person cannot be awakened, fails to respond normally to painful
stimuli, light or sound, lacks a normal sleep-wake cycle and does
not initiate voluntary actions.
All unconscious patients should have neurological
examinations to help determine the site and nature of the lesion,
to monitor progress, and to determine prognosis. Neurological
examination is most useful in the well-oxygenated,
normotensive, normoglycemic patient with no sedation, since
hypoxia, hypotension, hypoglycemia and sedating drugs
profoundly affect the signs elicited. Therefore, immediate
therapeutic intervention is a must to correct aberrations of
hypoxia, hypercarbia and hypoglycemia. Medications recently
taken that cause unconsciousness or delirium must be identified
quickly followed by rapid clinical assessment to detect the form
of coma either with or without lateralizing signs, with or without
signs of meningeal irritation, the pattern of breathing, the size
and reactivity of pupils and ocular movements, the motor
22 | Critical Care in Neurology
response, the airway clearance, the pattern of breathing and
circulation integrity, etc.
Special consideration must be given to neurological causes
which may lead to unconsciousness like status epilepticus (either
convulsive or non-convulsive), locked-in state, persistent
vegetative state and lastly brain stem death. Any disturbances of
thermoregulation must be measured.
Coma may result from a variety of conditions including
intoxication, metabolic abnormalities, central nervous system
diseases, acute neurologic injuries such as stroke, hypoxia or
traumatic injuries including head trauma caused by falls or
vehicle collisions. Looking for the pathogenesis of coma, two
important neurological components must function perfectly that
maintain consciousness. The first is the gray matter covering the
outer layer of the brain and the other is a structure located in
the brainstem called the reticular activating system (RAS or
ARAS), a more primitive structure that is in close connection
with the reticular formation (RF), a critical anatomical structure
needed for maintenance of arousal. It is necessary to investigate
the integrity of the bilateral cerebral cortices and the reticular
activating system (RAS), as a rule. Unilateral hemispheric lesions
do not produce stupor and coma unless they are of a mass
sufficient to compress either the contralateral hemisphere or the
brain stem (Bateman 2001). Metabolic disorders impair
consciousness by diffuse effects on both the reticular formation
and the cerebral cortex. Coma is rarely a permanent state
although less than 10% of patients survive coma without
significant disability (Bateman 2001); for ICU patients with
persistent coma, the outcome is grim.
Maneuvers to be established with an unconscious patient
include cardiopulmonary resuscitation, laboratory
investigations, a radiological examination to recognize brain
edema, as well as any skull, cervical, spinal, chest, and multiple
traumas. Intracranial pressure and neurophysiological
monitoring are important new areas for investigation in the
unconscious patient.