Brain damage, resulting in the irreversible loss of brain function, renders the individual incapable of life without the aid of a VENTILATOR. Criteria have been developed to recognise that irreversible brain damage without chance of recovery has occurred and to allow ventilation to be stopped: in the UK, these criteria require the patient to be irreversibly unconscious (not due to medication) and unable to regain the capacity to breathe spontaneously. (See also GLASGOW COMA SCALE and PERSISTENT VEGETATIVE STATE.)

All reversible pharmacological, metabolic, endocrine and physiological causes must be excluded, and there should be no doubt that irreversible brain damage has occurred. Two senior doctors carry out diagnostic tests to confirm that brain-stem reflexes are absent. These tests must be repeated after a suitable interval before death can be declared. Imaging techniques are not required for death to be diagnosed. The tests for brain-stem death are:

• Fixed and dilated pupils of the eyes

• Absent CORNEAL REFLEX

• Absent VESTIBULO-OCULAR REFLEX

• No cranial motor response to somatic (physical) stimulation

• Absent gag and cough reflexes

• No respiratory effort in response to APNOEA and adequate concentrations of CARBON DIOXIDE in the arterial blood.