Brain Death

Gary Salomon

Background

  • Brain death = complete and permanent loss of all brain function. Defined by coma with loss of capacity for consciousness, brainstem reflexes, and the ability to breathe independently.
  • See interactive brain death evaluation tool based on updated 2023 guidelines.

Checklist for determination of brain death (American Academy of Neurology)

1. Prerequisites (all must be checked)

  • Coma, irreversible and cause known.
  • Neuroimaging explains coma – usually CT or MRI.
  • Absence of CNS depressing drugs.
  • No evidence of residual paralytics (electrical stimulation if paralytics used).
  • Absence of severe acid-base, electrolyte, endocrine abnormality.
  • Normothermia or mild hypothermia (core temp >36°C).
  • SBP ≥100 mmHg; MAP ≥75 mmHg.
  • No spontaneous respirations.

2. Examination (all must be checked) – Attending MUST Be Present For Brain Death Exam

  • Patients must lack all evidence of responsiveness.
  • Noxious stimuli should not produce a motor response or eye movements other than spinally mediated reflexes in all extremities.
  • CRITICAL: Triple-flexion response (hip flexion, knee flexion, ankle dorsiflexion) is a spinal cord reflex and does NOT indicate brain function. This movement can occur in brain death and should NOT be confused with voluntary or brain-mediated movement.
  • Key distinction: Noxious stimuli above the foramen magnum should produce NO movement in face or body. Noxious stimuli below the foramen magnum should produce NO facial movement but may elicit spinal reflexes in the limbs.
  • If uncertain whether a movement is spinal vs. brain-mediated, consult experienced clinician or proceed to ancillary testing.
  • Absent brain stem reflexes:
    • Pupils mid-size or dilated (4-9 mm), no response to bright light bilaterally (if pupils are pinpoint, consider medication effect).
    • Corneal reflex absent (with maximal stimulation).
    • Oculocephalic reflex absent (tested only if C-spine integrity ensured).
    • Oculovestibular reflex (Cold water test; set bed at 30 degrees then irrigate each ear for 1 min watching for eye movement).
    • No facial movements to noxious stimuli at supraorbital nerve, temporomandibular joint (facial myokymia may be present spontaneously).
    • Cough and Gag reflexes absent to tracheal suctioning.

3. Apnea Testing (all must be checked) – Attending MUST Be Present

  • Pt must be hemodynamically stable.
  • Pre-test ABG should be acquired. 
  • Ventilator adjusted to provide normocarbia (PaCO2 35–45 mmHg) and normal pH (7.35-7.45).
  • Preoxygenate with 100% FiO2 and PEEP of 5 cmH2O for >10 min to PaO2 >200 mmHg.
  • Provide oxygen via a suction catheter to the level of the carina at 6 L/min or attach T-piece with continuous positive airway pressure (CPAP) at 10 cmH2O.
  • Disconnect ventilator.
  • Observe for spontaneous respirations.
  • Arterial blood gas drawn at 8–10 minutes, pt reconnected to ventilator.
  • Apnea test compatible with brain death if PCO2 ≥60 mmHg, or 20 mmHg rise from normal baseline value.
  • Abort apnea test for spontaneous respirations, hemodynamic instability (SBP<90 mmHg), or hypoxia (O2 sat <85% for 30 seconds).

4. Ancillary testing (Order one test if clinical examination cannot be fully performed due to pt factors or if apnea testing inconclusive/aborted)

  • Cerebral angiography (gold standard): No filling at level of carotid bifurcation or circle of Willis (Not to be confused with CT angiography).
  • HMPAO SPECT (Single photon emission computed tomography): no uptake of isotope in brain parenchyma.
  • Transcranial Doppler (only test that can be performed at bedside).
  • Note: EEG is not an approved ancillary test per updated AAN guidelines 2023.

5. Time of death determination once brain death is confirmed 

  • Time of ABG showing CO2 / pH level consistent with brain death during apnea test.
  • OR time of physician signature on ancillary test.

Organ Donation Caveats

  • Discussions about organ donation should take place between Tennessee Donor Services (TDS) and the surrogate. You SHOULD NOT be having conversations with the surrogate about donation. Direct questions to TDS.
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