Dr. Cohen

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Dr. Cohen

  1. 1. Brain Death Anatomy and Physiology <ul><li>Joel S. Cohen, M.D. </li></ul><ul><li>Associate Professor of Clinical Neurology </li></ul><ul><li>Albert Einstein College of Medicine </li></ul>
  2. 2. Historical Perspective <ul><li>Prior to the advent of mechanical respiration, death was defined as the cessation of circulation and breathing </li></ul>
  3. 3. Historical Perspective <ul><li>1959 Coma de’passe’ Mollaret and Goulon </li></ul><ul><li>1968 Irreversible Coma/Brain Death Harvard Medical School Ad Hoc Committee </li></ul><ul><li>1981 Uniform Determination of Death Act - President’s Commission for the Study of Ethical Problems in Medicine </li></ul><ul><li>1994 American Academy of Neurology Guidelines for the determination of Brain Death </li></ul><ul><li>2005 NYS Guidelines for Determining Brain Death </li></ul>
  4. 4. Brain Death Current Consensus <ul><li>Absent Cerebral Function </li></ul><ul><li>Absent Brainstem Function </li></ul><ul><li>Apnea </li></ul>
  5. 5. Normal Brain Anatomy
  6. 6. Normal Brain Anatomy Cerebral Cortex Brain Stem Reticular Activating System
  7. 7. Cerebral Cortex <ul><li>Cognition </li></ul><ul><li>Voluntary Movement </li></ul><ul><li>Sensation </li></ul>
  8. 8. Brain Stem
  9. 9. Brain Stem <ul><li>Midbrain </li></ul><ul><ul><li>Cranial Nerve III </li></ul></ul><ul><ul><ul><li>pupillary function </li></ul></ul></ul><ul><ul><ul><li>eye movement </li></ul></ul></ul>
  10. 10. Brain Stem <ul><li>Pons </li></ul><ul><li>Cranial Nerves IV, V, VI </li></ul><ul><ul><li>conjugate eye movement </li></ul></ul><ul><ul><li>corneal reflex </li></ul></ul>
  11. 11. Brain Stem <ul><li>Medulla </li></ul><ul><li>Cranial Nerves IX, X </li></ul><ul><ul><ul><li>Pharyngeal (Gag) Reflex </li></ul></ul></ul><ul><ul><ul><li>Tracheal (Cough) Reflex </li></ul></ul></ul><ul><li>Respiration </li></ul>
  12. 12. Reticular Activating System <ul><li>Receives multiple sensory inputs </li></ul><ul><li>Mediates wakefulness </li></ul>
  13. 13. Causes of Brain Death Normal Cerebral Anoxia
  14. 14. Causes of Brain Death Normal Cerebral Hemorrhage
  15. 15. Causes of Brain Death Normal Subarachnoid Hemorrhage
  16. 16. Causes of Brain Death Normal Trauma
  17. 17. Causes of Brain Death Normal Meningitis
  18. 18. Mechanism of Cerebral Death Increased Intracranial Pressure ICP>MAP is incompatible with life Neuronal Injury Decreased Intracranial Blood Flow Neuronal Swelling
  19. 19. Conditions Distinct From Brain Death <ul><li>Persistent Vegetative State </li></ul><ul><li>Locked-in Syndrome </li></ul><ul><li>Minimally Responsive State </li></ul>
  20. 20. Persistent Vegetative State <ul><li>Normal Sleep-Wake Cycles </li></ul><ul><li>No Response to Environmental Stimuli </li></ul><ul><li>Diffuse Brain Injury with Preservation of Brain Stem Function </li></ul>
  21. 21. Locked-in Syndrome Ventral Pontine Infarct <ul><li>Complete Paralysis </li></ul><ul><li>Preserved Consciousness </li></ul><ul><li>Preserved Eye Movement </li></ul>
  22. 22. Minimally Responsive State <ul><li>Diffuse or Multi-Focal Brain Injury </li></ul><ul><li>Preserved Brain Stem Function </li></ul><ul><li>Variable Interaction with Environmental Stimuli </li></ul>Static Encephalopathy
  23. 23. Brain Death Neurological Examination <ul><li>Clinical Prerequisites: </li></ul><ul><ul><li>Known Irreversible Cause </li></ul></ul><ul><ul><li>Exclusion of Potentially Reversible Conditions </li></ul></ul><ul><ul><ul><li>Drug Intoxication or Poisoning </li></ul></ul></ul><ul><ul><ul><li>Electrolyte or Acid-Base Imbalance </li></ul></ul></ul><ul><ul><ul><li>Endocrine Disturbances </li></ul></ul></ul><ul><ul><li>Core Body temperature > 32° C </li></ul></ul>
  24. 24. Brain Death Neurological Examination <ul><li>Coma </li></ul><ul><li>Absent Brain Stem Reflexes </li></ul><ul><li>Apnea </li></ul>
  25. 25. Coma <ul><li>No Response to Noxious Stimuli </li></ul><ul><ul><ul><li>Nail Bed Pressure </li></ul></ul></ul><ul><ul><ul><li>Sternal Rub </li></ul></ul></ul><ul><ul><ul><li>Supra-Orbital Ridge Pressure </li></ul></ul></ul>
  26. 26. Absence of Brain Stem Reflexes <ul><li>Pupillary Reflex </li></ul><ul><li>Eye Movements </li></ul><ul><li>Facial Sensation and Motor Response </li></ul><ul><li>Pharyngeal (Gag) Reflex </li></ul><ul><li>Tracheal (Cough) Reflex </li></ul>
  27. 27. Pupillary Reflex Pupils dilated with no constriction to bright light
  28. 28. Eye Movements Occulo-Cephalic Response “ Doll’s Eyes Maneuver”
  29. 29. Eye Movements Oculo-Vestibular Response “ Cold Caloric Testing”
  30. 30. Facial Sensation and Motor Response <ul><li>Corneal Reflex </li></ul><ul><li>Jaw Reflex </li></ul><ul><li>Grimace to Supraorbital or </li></ul><ul><li>Temporo-Mandibular Pressure </li></ul>
  31. 31. Apnea Testing <ul><li>Prerequisites </li></ul><ul><ul><ul><li>Core Body Temperature > 32° C </li></ul></ul></ul><ul><ul><ul><li>Systolic Blood Pressure ≥ 90 mm Hg </li></ul></ul></ul><ul><ul><ul><li>Normal Electrolytes </li></ul></ul></ul><ul><ul><ul><li>Normal PCO2 </li></ul></ul></ul>
  32. 32. Apnea Testing <ul><li>1. Pre-Oxygenation </li></ul><ul><ul><ul><li>100% Oxygen via Tracheal Cannula </li></ul></ul></ul><ul><ul><ul><li>PO2 = 200 mm Hg </li></ul></ul></ul><ul><li>2. Monitor PCO2 and PO2 with pulse oximetry </li></ul><ul><li>3. Disconnect Ventilator </li></ul><ul><li>4. Observe for Respiratory Movement until PCO2 = 60 mm Hg </li></ul><ul><li>5. Discontinue Testing if BP < 90, PO2 saturation decreases, or cardiac dysrhythmia observed </li></ul>
  33. 33. Confounding Clinical Conditions <ul><li>Facial Trauma </li></ul><ul><li>Pupillary Abnormalities </li></ul><ul><li>CNS Sedatives or Neuromuscular Blockers </li></ul><ul><li>Hepatic Failure </li></ul><ul><li>Pulmonary Disease </li></ul>
  34. 34. Observations Compatible with Brain Death <ul><li>Sweating, Blushing </li></ul><ul><li>Deep Tendon Reflexes </li></ul><ul><li>Spontaneous Spinal Reflexes- Triple Flexion </li></ul><ul><li>Babinski Sign </li></ul>
  35. 35. Confirmatory Testing <ul><li>Recommended when the proximate cause of coma is not known or when confounding clinical conditions limit the clinical examination </li></ul>
  36. 36. Confirmatory Testing EEG Normal Electrocerebral Silence
  37. 37. Confirmatory Testing <ul><li>Cerebral Angiography </li></ul>Normal No Intracranial Flow
  38. 38. Confirmatory Testing <ul><li>Technetium-99 Isotope Brain Scan </li></ul>
  39. 39. Confirmatory Testing <ul><li>MR- Angiography </li></ul>
  40. 40. Confirmatory Testing Transcranial Ultrasonography
  41. 41. Confirmatory Testing <ul><li>Somatosensory Evoked Potentials </li></ul>
  42. 42. <ul><li>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. </li></ul><ul><li>Albert Einstein </li></ul>

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