Definition

Irreversible and complete loss of cerebral and brainstem function. There is variation between states and institutions regarding the tests necessary to confirm this diagnosis. The following is based upon the UCSF Medical Center protocol.

Prerequisites

Patients must meet the following criteria before a diagnosis of brain death can be made:

• Presence of a diagnosis compatible with brain death (coma with known cause that is irreversible)
• Core body temperature > 32° Celsius; in those treated with therapeutic hypothermia brain death determination should occur >24 hours after rewarming is complete (> 35° Celsius)
• SBP > 90 mm Hg
• Arterial PaO2 > 50 mm Hg
• Serum sodium between 120 and 160 mEq/L
• Absence of a drug effect or metabolic abnormality which would interfere with reliable examination

Clinical Criteria for Diagnosis of Brain Death

• Absent cerebral function:  
  • Coma (if due to hypoxic-ischemic event, at least 24 hours must pass before a declaration of brain death is made)
  • No motor response to painful stimuli in all extremities 
• Absent brainstem function:
  • Pupils: mid-position to dilated, absent response to bright light
  • Absent vestibulo-ocular reflex (absent oculocephalic reflex [doll’s eyes] or negative cold caloric testing [irrigation of each ear with ice water])
  • Absent corneal reflex
  • Absent cough reflex
  • Absent gag reflex
  • Abnormal “apnea” test: demonstrates medullary destruction through non-responsiveness to high PaCO2 (see your institutional protocol)

Confirmatory Testing

Can be helpful and is required by law in some states. May include:

• Isoelectric EEG with machine set to high gain (again, patient cannot be on sedating medications) with lack of reactivity to somatosensory and audiovisual stimuli
• Absence of cerebral blood flow as demonstrated by conventional angiography or radioisotope brain scan