Brain Death Declaration Criteria and Procedures
Brain death determination requires two complete neurological examinations, including apnea testing, performed by different attending physicians and separated by an observation period, to confirm irreversible cessation of all brain function. 1
Prerequisites for Brain Death Evaluation
- Establish a known, irreversible cause of coma with evidence of an acute central nervous system injury consistent with brain death 2, 1
- Exclude confounding conditions that could affect neurological assessment:
- Ensure core temperature >35°C (>32.5°C in some guidelines) 2, 1
- Normalize blood pressure appropriate for age 2, 1
- Correct significant metabolic disturbances 1
- Ensure absence of CNS-depressing drugs, neuromuscular blockers, or sedatives that could affect the examination 2
- Allow appropriate time for drug clearance based on elimination half-life 1
Clinical Examination Components
Loss of cortical function assessment 2:
- Presence of deep coma (unresponsiveness to all stimuli)
- Lack of spontaneous motor activity
- Absence of response to deep painful stimuli
Brainstem reflex testing 2:
- Pupillary reflex: Absence of pupillary constriction to bright light
- Corneal reflex: No blinking response when cornea is touched with cotton swab
- Oculocephalic reflex ("doll's eyes"): Eyes passively follow head rotation without lag
- Oculovestibular reflex ("cold caloric"): No eye movement after instillation of 10ml ice water into ear canal
- Gag and cough reflexes: Absent response even with tracheal suctioning
Apnea Testing Procedure
- Pre-oxygenate the patient with 100% oxygen for 5-10 minutes 2, 1
- Disconnect from ventilator while providing oxygen via catheter or T-piece 2
- Monitor vital signs, oxygen saturation, and observe for respiratory effort 2
- Measure arterial blood gases to confirm PaCO₂ rises to ≥60 mmHg or ≥20 mmHg above baseline 2
- Apnea test is positive (supporting brain death) when no respiratory effort is observed despite adequate PaCO₂ elevation 2
- If the test cannot be completed due to hemodynamic instability, desaturation below 85%, or inability to reach target PaCO₂, an ancillary study should be performed 2
Observation Period and Examinations
- For neonates (37 weeks to 30 days): 24-hour observation period between examinations 2
- For infants and children (>30 days to 18 years): 12-hour observation period between examinations 2
- Two separate examinations by different attending physicians are required 2, 1
- The apnea test may be performed by the same physician, preferably the attending managing ventilator care 2
Ancillary Testing
- Not required unless clinical examination or apnea testing cannot be completed 2, 1
- Indicated when:
- Accepted ancillary tests include:
- If an ancillary study is equivocal, continue observation for 24 hours before repeating clinical evaluation or ancillary testing 2
Declaration of Death
- Death is declared after confirmation and completion of the second clinical examination and apnea test 2
- When ancillary studies are used, documentation of components from the second clinical examination must remain consistent with brain death 2
- All aspects of the clinical examination, apnea test, and ancillary studies must be appropriately documented 2, 1
- Confirmation of brain death by a second physician is prudent and required by law in some states 2
Common Pitfalls and Considerations
- Failure to recognize potential brain death occurs in 15-30% of eligible cases 2
- Spinal reflexes may be present even with complete brain death and should not be confused with brain activity 2, 4
- High gas flow rates with tracheal insufflation during apnea testing may promote CO₂ washout, preventing adequate PaCO₂ rise 2
- CPAP ventilation during apnea testing may falsely report spontaneous ventilation 2
- In cases with drug intoxication concerns, cerebral angiography is considered the gold standard for definitive proof of brain death 5