Brain death: clinical testing (Colombia)

What it is

Brain death is the irreversible loss of all brain function, including the brainstem, and it is legally the death of the person even while a ventilator keeps the heart beating and the organs perfused. It follows a catastrophic brain injury of known cause, most often trauma, haemorrhage or hypoxic-ischaemic injury after cardiac arrest. The determination is a clinical examination with three parts. First, prerequisites: imaging consistent with the cause, and the exclusion of conditions that can mimic it, such as sedative or neuromuscular-blocking drugs, severe electrolyte, acid-base or endocrine disturbance, hypothermia and hypotension. Second, the examination: deep coma with no response to a painful stimulus in the head, and absence of every brainstem reflex (pupillary light, corneal, oculocephalic, oculovestibular, gag and cough). Third, the apnoea test, which shows that a high arterial carbon dioxide does not trigger any breath. When a part of the examination or the apnoea test cannot be done safely, an ancillary test such as a cerebral blood flow study or an EEG is used. In Colombia the diagnosis is regulated by Decree 2493 of 2004: it is made by two or more doctors who are not part of the transplant programme, one of them a neurologist, using the clinical signs set out in the decree, with a confirmatory test when a sign cannot be confirmed, and separate rules for children under two (see the Ethics page on the legal criteria).

What to assess

• The cause: a catastrophic brain injury seen on imaging and consistent with the loss of all brain function.
• Confounders: sedatives, opioids and neuromuscular blockers (check a train-of-four), alcohol and poisons, enough time for drugs to clear.
• Physiology: core temperature above 36 °C, systolic blood pressure at least 100 mmHg or the target the protocol sets, and no severe electrolyte, glucose or acid-base disturbance.
• The neck: the oculocephalic test is not done until a cervical spine injury is excluded.
• Who examines: doctors trained in the determination, independent of any organ donation team.

How it is done (and why)

1. Confirm a known, irreversible, catastrophic cause on imaging — brain death cannot be diagnosed without one.
2. Exclude confounders: drugs, neuromuscular blockade, hypothermia, hypotension, metabolic disturbance — each can mimic absent brain function.
3. Apply a painful stimulus in the cranial nerve territory and to the limbs — no cerebral motor or facial response is allowed.
4. Test pupils, corneal, oculocephalic and oculovestibular reflexes — each tests a different level of the brainstem.
5. Test gag and cough with tracheal suction — these are the lowest brainstem reflexes, in the medulla.
6. Preoxygenate, then disconnect and observe for breathing while CO2 rises, confirmed by a blood gas — tests the medullary respiratory centre.
7. Stop the apnoea test if hypotension, desaturation or arrhythmia occur, and use an ancillary test — safety comes first.
8. Use an ancillary test (cerebral blood flow study or EEG) when any part cannot be completed — confirms the absence of brain function.
9. Document every prerequisite, finding, time and examiner — the time of death is when the determination is complete.

Findings that change the plan

• Movements of the limbs to stimulation, sweating or tachycardia can come from the spinal cord and do not exclude brain death.
• Diabetes insipidus, hypotension and hypothermia are common after brainstem death: treat them to allow testing and organ care.
• A vegetative state, locked-in syndrome or deep sedation are not brain death: the brainstem still works in all three.
• Do not start the examination while a confounder is present; wait or use an ancillary test.
• In children under two, Colombian law and paediatric guidelines require age-specific observation periods and repeated examinations.

Next step

• Follow the hospital protocol and the Colombian rules for the number and independence of examiners and the confirmatory tests.
• Notify the organ and tissue donation network in line with local rules once brain death is suspected, without involving the transplant team in the diagnosis.
• Tell the family clearly that the person has died, with time, privacy and support.
• Continue organ support only for donation or as the law and protocol allow, and record the time of death in the clinical record.

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Elsewhere in DurgiPedia

• Brain death: the ethical and legal criteria in Colombia
• Ley 1805 de 2016: presumed consent for organ donation
• Limiting life-sustaining treatment: withholding and withdrawing
• Diagnosing death: the signs of death
• Pupils: light reflex and abnormal pupils (Marcus Gunn, Horner, Argyll Robertson)

Connections

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Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: Brain Death (StatPearls (NCBI Bookshelf), 2024).

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