Surgical Critical Care: Brain Death

Brain Death

Prognosis

  • Two Factors are 100% Specific for Poor Outcome in Absence of Cofounding Factors:
    • Absent or Extensor Motor Response on Day #3
    • Absent Pupillary or Corneal Reflexes on Day #3

Diagnosis

  • Criteria:
    • No Spontaneous Respirations
    • No Response to Pain
    • No Cranial Nerve Reflexes
    • *Can Still Have Spinal Cord/Deep Tendon Reflexes
  • Excludes Dx:
    • Hypothermia (Core Temperature < 34-36 C)
    • Hypotension (Systolic Blood Pressure < 90-100 mmHg)
    • Significant Metabolic Derangements (Electrolytes, Acid-Base or Endocrine)
    • Depressant Drugs
  • Definitive Testing (If All Criteria Met):
    • Preferred Test: Positive Apnea Test
    • If Hemodynamically Unstable & Unable to Tolerate Time Off Ventilator:
      • Four-Vessel Cerebral Angiogram (Generally the Gold Standard but More Invasive)
      • MRA/CTA
      • Nuclear Cerebral Scintigraphy
      • Less Preferred: EEG or Transcranial Doppler

Cranial Nerve Reflexes

  • Pupillary Light Reflex – Light Shown into the Eye
    • Normal: Prompts Pupil Constriction
    • Abnormal: Pupil Does Not Constrict
  • Corneal Reflex – Cornea Touched with Cotton Swab or Saline
    • Normal: Prompts Blinking
    • Abnormal: Does Not Blink
  • Gag Reflex – Touching the Posterior Pharyngeal Wall
    • Normal: Prompts Palate Elevation
    • Abnormal: No Palate Elevation
  • Cough Reflex – Tracheal Suctioning
    • Normal: Prompts Coughing
    • Abnormal: Does Not Cough
  • Oculocephalic (Doll’s Eyes) Reflex – With Eyes Held Open the Head is Briskly Turned Side-to-Side & Held at the End of the Turn
    • Normal: Eyes Rotate to the Opposite Side of Head Rotation (Continue to Look Forward)
    • Abnormal: Eyes Do Not Rotate
    • *Must First Ensure that the C-Spine is Clear
  • Oculovestibular (Cold Caloric) Reflex – With Head Elevated at 30 Degrees, 200 cc of Ice Water is Instilled into the External Ear Canal
    • Normal: Nystagmus with Eye Deviation to the Tested Ear
    • Abnormal: No Nystagmus Seen

Apnea Test

  • Test:
    • Ensure CO2 Normal (35-45 mmHg) Before Starting
    • Preoxygenate with 100% O2
    • Disconnect the Ventilator for 10 Minutes
      • Continue to Deliver O2
  • Results:
    • Positive: PaCO2 > 60 mmHg or Increase by > 20 mmHg
    • Negative: Spontaneous Breathing, SBP < 90 or Desaturation of PaO2 < 85
      • Restart Vent

Children (≤ 18 Years)

  • Brain Death Pronunciation Requires Two Separate Examinations Preformed by Two Separate Physicians with an Observation Period In Between
    • Age ≤ 30 Days: 24 Hours Between
    • Age > 30 Days:12 Hours Between

Physiologic Derangements After Brain Death

  • Cardiac Dysrhythmias – From Increased Catecholamines & Myocardial Dysfunction
  • Circulatory Collapse with Peripheral Vasodilation
  • Hypovolemia
  • Hypothermia
  • Coagulopathy
  • Metabolic Acidosis
  • Hypernatremia with Diabetes Insipidus – From Hypothalamic Dysfunction
  • Hyperglycemia
  • Hypothyroidism

Brain Death on Nuclear Cerebral Scintigraphy