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12 Cards in this Set
- Front
- Back
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Popular Harvard criteria for brain death
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Unresponsive, no movements, apnea, areflexia (of cranial nerves), flat EEG
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Definition of death
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Irrev cessation of function of the organism as a whole
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Criterion for death
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Irrev cessation of function of a critical number of neurons of the cerebral hemispheres and brain stem
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With brain death, increased ICP can cause what?
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Transtentorial brain herniation, loss of intracranial blood flow, secondary diffuse neuronal death.
Can confirm this if there is no blood flow to brain (ICP is greater than systolic BP...if heart is working) |
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Tests of death
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If no ventilatory support - cardiopulm tests are fine
If there is, need a specific brain death test. SHOULD BE NO FALSE POSITIVES!!! |
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This lecturer suggests....
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requiring a confirmatory test showing the absence of intracranial blood flow.
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Exam of a pt with brain death
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Unresponsive to brain stem stimuli
Cranial nerve areflexia Apnea (lets CO2 climb very high) Limb tendon reflexes and Lazarus sign can persist (crossing arms over chest after removing from ventilator) |
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Time of death
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When they satisfy the second set of tests for brain death.
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Vegetative state
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Preservation of brain stem, unawareness of self, sleep-wake cycles.
Becomes persistent after 1 month. Preserved autonomic and hyopthalamic function to survive for long intervals. Preserved cranial nerve reflexes They may respond to visual threats. They also can have startle myoclonus. |
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Pathology of vegetative state
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Nontraumatic - diffuse cortical laminar necrosis.
Traumatic - Diffuse axonal injury Lesions spare the brainstem BUT THALAMUS IS DISCONNECTED FROM THE CORTEX!!! 37 and 43% false positive rates of diagnosis. |
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Minimally conscious state
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There is minimal, but definite, evidence of self or environmental awareness.
They follow commands, gesture yes/no, reach for objects, smile/cry. |
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Usefulness of fMRI
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Good to check for presence of awareness behavior when the neuro exam can't tell you.
(e.g. imagine playing tennis, the supp motor cortex will light up) |
