Basic assessments

1. Pupillary functions may be normal if the lesion is rostral to
the midbrain, while if the injury is diffuse, e.g., global cerebral
anoxia or ischemia, the pupillary abnormality is bilateral. Pupil
size is important as midposition (2-5 mm) fixed or irregular
pupils imply a focal midbrain lesion; pinpoint reactive pupils
occur in global hypoxic ischemic insult with pontine damage, or
poisoning with opiates and cholinergic active materials; and
bilateral fixed and dilated pupils can reflect central herniation
or global hypoxic ischemic or poisoning with barbiturates,
scopolamine, and atropine. Unilateral dilated pupil suggests
compression of the third cranial nerve and midbrain, which
necessitates an immediate search for a potentially correctable
abnormality to avoid irreversible injury. In case of post-cardiac
arrest coma, if pupils remain nonreactive for more than 6-8
hours after resuscitation, the prognosis for neurological
recovery is generally guarded (Stevens 2006).
2. Posturing of the body: decorticate posturing (painful stimuli
provoke abnormal flexion of upper limbs) indicates a lesion at
the thalamus or cortical damage; decerebrate posturing (the
arms and legs extend and pronate in response to pain) denotes
that the injury is localized to the midbrain and upper pons; an
injury of the lower brain stem (medulla) leads to flaccid
extremities.
How to Approach an Unconscious Patient | 25
3. Ocular reflexes: assessment of the brainstem and cortical
functions happen through special reflex tests such as the
oculocephalic reflex test (Doll’s eyes test), oculovestibular reflex
test (cold caloric test), nasal tickle, corneal reflex, and the gag
reflex.
4. Vital signs: temperature (rectal is most accurate), blood
pressure, heart rate (pulse), respiratory rate, and oxygen
saturation (Inouye 2006). It is mandatory to evaluate these basic
vital signs quickly and efficiently to gain insight into a patient’s
metabolism, fluid status, heart function, vascular integrity, and
tissue oxygenation status.
5. The respiratory pattern (breathing rhythm) is significant and
should be noted in a comatose patient. Certain stereotypical
patterns of breathing have been identified including Cheyne-
Stokes respiratory pattern, where the patient’s breathing is
described as alternating episodes of hyperventilation and apnea,
a dangerous pattern often seen in pending herniation, extensive
cortical lesions, or brainstem damage. Apneustic breathing is
characterized by sudden pauses of inspiration and is due to
pontine lesion. Ataxic (Biot’s) breathing is an irregular chaotic
pattern and is due to a lesion of the medulla. The first priority in
managing a comatose patient is to stabilize the vital functions,
following the ABC rule (Airway, Breathing, and Circulation).
Once a person in a coma is stable, assessment of the underlying
cause must be done, including imaging (CT scan, CT
angiography, magnetic resonance imaging (MRI), magnetic
resonance angiography (MRA) and magnetic resonance
venography (MRV) if needed ) and special studies, e.g., EEG and
transcranial Doppler.
Coma is a medical emergency, and attention must first be
directed to maintaining the patient’s respiration and circulation
as previously mentioned using intubation and ventilation,
administration of intravenous fluids or blood and other
supportive care as needed. Measurement of electrolytes is a
commonly performed diagnostic procedure, most often sodium
26 | Critical Care in Neurology
and potassium; chloride levels are rarely measured except for
arterial blood gases (Bateman 2001). Once a patient is stable and
no longer in immediate danger, the medical staff should start
parallel work, first investigating the patient to find out any
underlying pathology of his presenting illness, second, managing
the presenting illness symptoms. Infections must be prevented
and a balanced nutrition provided. The nursing staff, to guard
against pressure ulcers, may move the patient every 2–3 hours
from side to side and, depending on the state of consciousness,
sometimes to a chair. Physical therapy may also be used to
prevent contractures and orthopedic deformities that would
limit recovery for those patients who emerge from coma
(Wijdicks 2002).
People may emerge from a coma with a combination of
physical, intellectual and psychological difficulties that need
special attention; recovery usually occurs gradually and some
patients acquire more and more ability to respond, others never
progress beyond very basic responses. Regaining consciousness
is not instant in all comatose patients: in the first days, patients
are only awake for a few minutes, the duration of awake time
gradually increases, until they regain full consciousness. The
coma patient awakens sometimes in a profound state of
confusion, not knowing how they got there and sometimes
suffering from dysarthria, the inability to articulate speech, and
other disabilities. Time is the best general predictor of a chance
of recovery: after 4 months of coma caused by brain damage, the
chance of partial recovery is less than 15%, and the chance of full
recovery is very low (Wijdicks 2002). Coma which lasts seconds
to minutes may result in post-traumatic amnesia (PTA) lasting
from hours to days; recovery occurs over days to weeks. Coma
which lasts hours to days may result in PTA lasting from days to
weeks; its recovery occurs over months. Coma which lasts weeks
may result in PTA that lasts months; recovery occurs over
months.