Brain Death Criteria

In general, death can occur either by cardiac or brain death. Cardiac death is the irreversible cessation of circulatory and respiratory functions. Whereas brain death is the irreversible cessation of all functions of the entire brain, including the brainstem. Patients with brain death can be kept “alive” despite not having brain or brainstem function. This raises the need to establish criteria for assessing brain death.

• Vital signs and general criteria that must be met before considering a judgement of brain death (or performing further investigations)
  • Core temperature > 36 C (normothermic for at least 24 hours)
  • SBP ≥ 100 mmHg (with or without pressors)
  • Absence of drugs that could stimulate brain death (alcohol, sedatives, narcotics, neuromuscular blockers)
  • Rule out organic conditions that could mimic brain death (hepatic encephalopathy, hyperosmolar coma, extreme abnormalities in glucose, sodium and pH)
• Criteria for brain death
  1. Absence of consciousness: unresponsive to external stimuli and unaware of their surrounding (GCS of 3)
  2. Absence of brainstem reflexes: gag or pupillary reflex
  3. Absence of breathing: apnea test by disconnecting the patient form the ventilator for some time and assessing whether the resulting hypercapnia stimulates the patient to breathe. Persistent apnoea suggests there is no respiratory drive from the brainstem. A confirmatory test such as EEG, transcranial doppler, or nuclear medicine cerebral blood flow study can be used in place of an apnea test in case the patient is too unstable

Absence of brainstem reflexes