Diagnosing death Flashcards
what three descending tracts run through the cerebral peduncles
corticospinal tract (UMN of spinal nerves supplies motor function limbs and torso)
corticopontine tract (UMN of cranial nerves, V, VII, XII)
corticobulbar tract (UMN of cranial nerves supplies motor function to face, head and neck)
where does the midbrain pass through
tentorial notch
what is the difference between superior and inferior colliculi
superior: VISUAL REFLEXES
inferior: AUDITORY REFLEXES
a transverse furrow separates two inferior components of the brainstem
what three cranial nerves run through this furrow
VI
VII
VIII
where does the most inferior component of the brainstem join the spinal cord
ATLAS
all cranial nerve nuclei are located in the brain stem except for two, which are?
olfactory and optic
autonomic fibres are located in the brainstem principally running with with cranial nerves?
III
VII
IX
X
what is the key functions of the brainstem
-regulation of arousal and conscious awareness
-maintenance of spontaneous respiration and cv control
-transmission of motor and sensory impulses to and from central and peripheral nervous systems
what is a definition of death
irreversible loss of the capacity for consciousness
combined with irreversible loss of the capacity to breathe
who can carry out a death diagnosis and what is the criteria
TWO qualified doctors
who have been fully registered with the GMC for at least 5 years
one must be a consultant
neither must be on a transplant team, or have a conflict of clinical interest
two separate occasions
what are the 3 essential components of diagnosing death
- PRECONDITIONS- patient has suffered irreversible brain damage from a known cause and is deeply unconscious, apnoeic, mechanically ventilated
- REVERSIBLE influences on conscious level must be excluded- SEDATIVE DRUGS, HYPOTHERMIA, SIGN ENDOCRINE, METABOLIC DISTURBANCES
- formal testing for the absence of brain stem activity is carried out once the preconditons are met and reversible influences have been excluded
what is the time of death defined as
death is not confirmed until the second test has been completed
the legal time:
-when the first test indicates death due to the absence of brainstem reflexes
how do you test fir absence of brain-stem reflexes
6 types
what are the cranial nerves being tested
- PUPILS ARE FIXED- no response to sharp changes in light intensity
-OPTIC AND OCCULOMOTOR - NO CORNEAL REFLEX
-TRIGEMINAL AND FACIAL - ABSENT OCULO-VESTIBULAR REFLEXES
-No eye movements are seen during or following the slow injection of at least 50mls of ice cold water over one minute into each external auditory meatus in turn. Clear access to the tympanic membrane must be established by direct inspection and the head should be at 300 to the horizontal plane, unless this positioning is contraindicated by the presence of an unstable spinal injury.
-VESTIBULOCOCHLEAR, OCULOMOTOR - No motor responses within the cranial nerve distribution can be elicited by adequate stimulation of any somatic area. No motor response can be elicited within the cranial nerve or somatic distribution in response to supraorbital pressure.
-TRIGEMINAL AND FACIAL - NO COUCH REFLEX to bronchial stimulation by a suction catheter placed down the trachea to the carina
or gag response to stimulation of the posterior pharync wih a spatula
-GLOSSOPHARYNGEAL AND VAGUS
- SHOUL DNOT BE PERFORMED IF ANY OTHER TESTS CONFIRM BRAINSTEM REFLEXES
-test respiratory response to hypercabia
-patient is disconnected form the ventilator,
allowing the pCO2 to rise above 6.5 kPa and the pH to fall below 7.4. Oxygenation is maintained by insufflating oxygen down the tracheal tube via a catheter. The patient is observed for respiratory effort for a period of five minutes.
