Brain Death Anatomy and Physiology Joel S. Cohen, M. D. Associate Professor of Clinical Neurology Albert Einstein College of Medicine
Historical Perspective Prior to the advent of mechanical respiration, death was defined as the cessation of circulation and breathing
Historical Perspective n n 1959 Coma de’passe’ Mollaret and Goulon 1968 Irreversible Coma/Brain Death Harvard Medical School Ad Hoc Committee n 1981 Uniform Determination of Death Act - President’s Commission for the Study of Ethical Problems in Medicine n 1994 American Academy of Neurology Guidelines for the determination of Brain Death n 2005 NYS Guidelines for Determining Brain Death
Brain Death Current Consensus n Absent Cerebral Function n Absent Brainstem Function n Apnea
Normal Brain Anatomy
Normal Brain Anatomy Cerebral Cortex Brain Stem Reticular Activating System
Cerebral Cortex n n n Cognition Voluntary Movement Sensation
Brain Stem
Brain Stem Midbrain Cranial Nerve III n pupillary function n eye movement
Brain Stem Pons Cranial Nerves IV, V, VI n conjugate eye movement n corneal reflex
Brain Stem Medulla Cranial Nerves IX, X n Pharyngeal (Gag) Reflex n Tracheal (Cough) Reflex Respiration
Reticular Activating System n Receives multiple sensory inputs n Mediates wakefulness
Causes of Brain Death Normal Cerebral Anoxia
Causes of Brain Death Normal Cerebral Hemorrhage
Causes of Brain Death Normal Subarachnoid Hemorrhage
Causes of Brain Death Normal Trauma
Causes of Brain Death Normal Meningitis
Mechanism of Cerebral Death Neuronal Swelling Neuronal Injury ICP>MAP is incompatible with life Decreased Intracranial Blood Flow Increased Intracranial Pressure
Conditions Distinct From Brain Death n Persistent Vegetative State n Locked-in Syndrome n Minimally Responsive State
Persistent Vegetative State n Normal Sleep-Wake Cycles n No Response to Environmental Stimuli n Diffuse Brain Injury with Preservation of Brain Stem Function
Locked-in Syndrome Ventral Pontine Infarct n Complete Paralysis n Preserved Consciousness n Preserved Eye Movement
Minimally Responsive Static Encephalopathy n Diffuse or Multi-Focal Brain Injury n Preserved Brain Stem Function n Variable Interaction with Environmental Stimuli
Brain Death Neurological Examination Clinical Prerequisites: n Known Irreversible Cause n Exclusion of Potentially Reversible Conditions n Drug Intoxication or Poisoning n Electrolyte or Acid-Base Imbalance n Endocrine Disturbances n Core Body temperature > 32° C
Brain Death Neurological Examination n Coma n Absent Brain Stem Reflexes n Apnea
Coma No Response to Noxious Stimuli n Nail Bed Pressure n Sternal Rub n Supra-Orbital Ridge Pressure
Absence of Brain Stem Reflexes n Pupillary Reflex n Eye Movements n Facial Sensation and Motor Response n Pharyngeal (Gag) Reflex n Tracheal (Cough) Reflex
Pupillary Reflex Pupils dilated with no constriction to bright light
Eye Movements Occulo-Cephalic Response “Doll’s Eyes Maneuver”
Eye Movements Oculo-Vestibular Response “Cold Caloric Testing”
Facial Sensation and Motor Response n Corneal Reflex n Jaw Reflex Grimace to Supraorbital or Temporo-Mandibular Pressure n
Apnea Testing Prerequisites n Core Body Temperature > 32° C n Systolic Blood Pressure ≥ 90 mm Hg n Normal Electrolytes n Normal PCO 2
Apnea Testing 1. Pre-Oxygenation n 100% Oxygen via Tracheal Cannula n PO 2 = 200 mm Hg 2. Monitor PCO 2 and PO 2 with pulse oximetry 3. Disconnect Ventilator 4. Observe for Respiratory Movement until PCO 2 = 60 mm Hg 5. Discontinue Testing if BP < 90, PO 2 saturation decreases, or cardiac dysrhythmia observed
Confounding Clinical Conditions n Facial Trauma n Pupillary Abnormalities n CNS Sedatives or Neuromuscular Blockers n Hepatic Failure n Pulmonary Disease
Observations Compatible with Brain Death n Sweating, Blushing n Deep Tendon Reflexes n Spontaneous Spinal Reflexes- Triple Flexion n Babinski Sign
Confirmatory Testing Recommended when the proximate cause of coma is not known or when confounding clinical conditions limit the clinical examination
Confirmatory Testing EEG Normal Electrocerebral Silence
Confirmatory Testing Cerebral Angiography Normal No Intracranial Flow
Confirmatory Testing Technetium-99 Isotope Brain Scan
Confirmatory Testing MR- Angiography
Confirmatory Testing Transcranial Ultrasonography
Confirmatory Testing Somatosensory Evoked Potentials
Concern for man and his fate must always form the chief interest of all technical endeavors. Never forget this in the midst of your diagrams and equations. Albert Einstein
Скачать презентацию Brain Death Anatomy and Physiology Joel S Cohen
Brain death.ppt