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3.1
DEFINITION
Brain death is the irreversible cessation of all functions
of the entire brain including the brain-stem.
3.2
PRECONDITIONS
FOR THE DIAGNOSIS OF BRAIN DEATH
Before proceeding to make the diagnosis of brain death on
a patient, the following conditions should be present.
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Patient is in coma and the cause of coma has been firmly established.
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Patient has no spontaneous respiration and is supported by a
ventilator.
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The event causing brain-death occurred at least six hours previously
and the cause of death has been clearly determined
(i.e., head trauma, brain hemorrhage, etc).
- Patient is not in cardiovascular shock.
- Obvious metabolic and endocrinal derangements have been corrected.
- No response to any kind of stimuli.
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Complete areflexia. However,
simple spinal cord reflexes may be present.
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3.3 EXCLUSIONS
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Patient should not be hypothermic. The core temperature must be above 35.5 C before testing for
brain death. If
the temperature is below this, the patient must be
warmed-up.
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Patient is not receiving any sedatives, muscle relaxants,
anticonvulsants, hypnotics, narcotics or
anti-depressants.
Blood levels of these drugs should be nil or
insignificant if the patient was on any of these
drugs previously.
Toxicology screen must be done especially in cases
of road traffic accidents, drug overdoses and
unexplained causes of coma, and in other cases, as
deemed necessary.
If indicated, and facilities are not
available for estimating the blood levels, an
interval of five days should lapse before testing
for brain-death.
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Patients with metabolic and endocrine causes of coma should be
excluded.
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Patient should not have any sign of cerebral activity like
decerebrate or decorticate posture and seizure
activities.
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3.4
HOW TO DIAGNOSE BRAIN DEATH?
Once
the patient is found to have the necessary preconditions and
exclusions, one should proceed with the clinical examination
as per the recommendation in the brain-death documentation
form (Appendix II). The
findings are to be recorded in the prescribed form and signed
by the physicians conducting the examination.
They must also be available also after the stipulated
observation interval, to carry-out the second examination and
sign the brain-death certificate.
3.4.1
Initial Clinical Examination
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- Confirm
that the patient is in coma.
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Evaluate
the patient for the presence of any seizure activity
and any decerebrate or decorticate movements.
None should be found in a brain-dead patient.
Presence of spinal myoclonus and/or spinal
reflexes alone does not indicate brain
viability and does not exclude brain
death.
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Test
for absence of motor response to painful
stimulation.
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For example,
absence of grimacing upon applying pressure over the frontal
sinus (Figure 3*).
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Figure 3. Testing for motor response to painful stimulus
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3.4.2 Tests
for Brain-stem reflexes
After
the initial evaluation
described above,
tests are done to demonstrate the absence of brain-stem
reflexes. These
tests have to be done in the following order: (If anyone of
these reflexes is preserved, there is no need to proceed
further).
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a)
Pupillary response to light
Shine
a bright beam of light from a suitable source, e.g., a
pen flashlight, on to the open eyes (Figure 4).
In a brain-dead patient, no response, neither
direct nor consensual, is seen to the stimulus in either
eye.
Both eyes must be tested. Make sure that mydriatic or meiotic eye drops or drugs have
not been used in the recent past prior to carrying out
the test.
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Figure 4. Testing for pupillary response to light
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b)
Corneal reflex
Touch
the cornea with a wisp of cotton wool (Figure 5).
If the brain stem is dead, no blinking response
is noted on either side.
The test should be performed on both sides.
In
a patient with suspected brain death, much firmer
pressure is justified while doing this test.
The use of a cotton swab is more suitable.
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Figure 5. Testing for
corneal reflex
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