What is the appropriate length of time to declare someone brain dead?

Appropriate Observation Period for Brain Death Declaration

The observation period between brain death examinations is age-dependent: 24 hours for term newborns (37 weeks gestation to 30 days of age) and 12 hours for infants and children (>30 days to 18 years), with two complete examinations by different attending physicians required before death can be declared. 1

Age-Specific Observation Periods

Term Newborns (37 weeks gestation to 30 days)

• A 24-hour observation period between the first and second examination is required 1
• This longer interval accounts for limited data in neonates and potential biological differences in neonatal brain metabolism and response to injury 1
• Historical data show that brain-dead neonates averaged 75 hours from initial examination to final confirmation, with none recovering neurologic function 1

Infants and Children (>30 days to 18 years)

• A 12-hour observation period between examinations is required 1
• Literature review of 171 children found no recovery of neurologic function after meeting accepted brain death criteria, supporting this shorter interval 1
• There is no biological justification for different durations in children older than one month compared to adults 1

Critical Prerequisites Before Starting the Clock

Initial Waiting Period

• Wait 24 hours following cardiopulmonary resuscitation or severe acute brain injury before initiating the first brain death examination if there are concerns about examination validity 1
• This initial stabilization period is separate from and precedes the observation period between examinations 1
• Assessment immediately after resuscitation may be unreliable due to evolving neurologic changes 1

Confounding Factors Must Be Corrected

• Core body temperature must be ≥35°C (95°F) 1
• Hypotension and metabolic disturbances must be corrected 1
• Sedatives, analgesics, neuromuscular blockers, and anticonvulsants must be discontinued for adequate clearance based on elimination half-life 1
• Blood levels should be in low to mid-therapeutic range; brain death diagnosis should not be made with supratherapeutic levels present 1

Shortening the Observation Period

If an ancillary study (EEG showing electrocerebral silence or cerebral blood flow study showing absent flow) performed with the first examination supports brain death, the observation period can be shortened and the second examination performed at any time thereafter for all age groups 1

Requirements When Shortening

• All components of the second clinical examination that can be safely completed must still be performed 1
• A second apnea test must be completed (unless medically contraindicated) 1
• All findings must remain consistent with brain death 1

Examination Requirements

Two Complete Examinations Required

• Two separate examinations by different attending physicians are mandatory, regardless of ancillary study results 1
• The first examination determines the patient meets brain death criteria 1
• The second examination confirms an unchanged and irreversible condition 1
• The apnea test may be performed by the same physician, preferably the attending managing ventilator care 1

Apnea Testing Criteria

• PaCO₂ must reach ≥60 mmHg AND ≥20 mmHg above baseline with no respiratory effort observed 1
• Two apnea tests are required (one with each examination) unless clinically contraindicated 1
• If apnea testing cannot be safely completed, an ancillary study must be performed 1

Declaration of Death

Death is declared at the time of the second examination and apnea test when all criteria are met and the condition remains unchanged 1

Documentation Requirements

• All prerequisites must be documented as corrected 2
• Both complete neurological examinations with detailed findings 2
• Results of both apnea tests 2
• If ancillary studies used, specific findings consistent with brain death 2, 3

Common Pitfalls to Avoid

Insufficient Observation in Special Circumstances

• For infratentorial/posterior fossa lesions, standard observation periods may be inadequate 4
• Research shows 34% of infratentorial lesions had non-confirmatory ancillary tests versus only 2% for supratentorial lesions, with optimal observation exceeding 32.5 hours for infratentorial injuries 4
• Consider longer observation or repeat ancillary testing for brainstem/posterior fossa pathology 4

Premature Testing with Supratentorial Lesions

• For supratentorial lesions, performing ancillary tests within 2 hours of the first clinical examination may yield false results 4
• Studies show 3% non-confirmatory rate when testing <2 hours versus 0% when delayed >2 hours 4

Medication Effects

• Do not proceed with brain death determination if medication effects cannot be excluded 1
• Neuromuscular blockade must be confirmed reversed using nerve stimulator with documented twitch response 1
• Consider unusual causes like neurotoxins or organophosphate exposure if etiology unclear 1

Ancillary Study Limitations

• EEG activity may persist after clinical brain death in up to 20% of cases 5
• Low-voltage theta/beta activity can persist up to 72 hours, and sleep-like activity up to 168 hours after brain death 5
• Ancillary studies are not substitutes for clinical examination and do not override clinical criteria 1
• If ancillary study is equivocal or non-confirmatory, wait 24 hours before repeating clinical evaluation or ancillary testing 1