Is a person who is brain dead really "dead"?
A person who is brain dead is truly and unequivocally dead and will never wake up nor regain consciousness again.
Brain death occurs when there is total and irreversible cessation of all functions of the brain in a person. When a person is declared brain dead, he will not be able to breathe on his own and will need to be artificially supported by a ventilator. Once the ventilator is switched off, the person’s heart will cease to beat as his brain has already stopped functioning. Brain death is accepted as a legal definition of death in Singapore and in other advanced countries. It is determined based on a well-defined standard set of clinical criteria. This definition is similar to those used in countries such as Australia, Canada, Denmark, the United Kingdom and the United States.
There are seven clinical criteria for determining irreversible cessation of all functions of the brain. Brain death can only be certified if all seven clinical criteria are met. The seven clinical criteria are as follows:
1. Pupils do not constrict when exposed to direct, strong light. (Absent pupillary light reflex)
Normal response: Pupils constrict when exposed to direct, strong light.
2. There is no blink reflex when the corneas are stimulated. (Absent corneal reflex)
Normal response: The eyelid blinks when the cornea (area over the pupils) is stimulated with a cotton wisp.
3. There is no response to painful stimulus, excluding spinal reflexes. (Absent pain response)
Normal response: The subject will attempt to withdraw from, localise or remove the painful stimulation.
4. The eye gaze follows the direction of the head when turned from side to side. (Absent oculocephalic reflex)
Normal response: The eyes will remain fixed on forward gaze even when the head is turned from side to side.5. There is no gag reflex in response to stimulation of the throat or upper air passages. (Absent gag reflex)
Normal response: Stimulation of the throat or the upper air passages will induce gagging.
6. There is no eye response on instillation of 50 cubic centimetres of ice-cold water into each ear. (Absent vestibulo-ocular response)
Normal response: The eye will twitch when each ear is instilled with cold water.
7. There is no spontaneous breathing when removed from the ventilator even with rising carbon dioxide concentration in the blood. (Positive apnea test)
Normal response: Spontaneous breathing will occur with rising carbon dioxide concentration (> 50 millimetres of mercury) in the blood.
Supplementary tests can be used to complement the clinical tests. These tests are carried out to demonstrate the presence or absence of blood flow in the brain. The absence of blood flow in the brain is confirmatory of brain death.However, these tests are not substitutes for the clinical criteria. If six of the seven clinical tests can be performed, the criteria for these six tests must be fully met, before the doctor proceeds to carry out a supplementary test.On 1 July 2004, the Interpretation (Determination and Certification of Death) Regulations were amended to allow two supplementary tests to be used for brain death certification:1. Cerebral angiography: A contrast agent / dye is injected into the bloodstream and tracked in real-time by x-ray. The inability of the contrast agent to reach the brain will confirm the absence of blood flow in the brain; or
2. Radionuclide Perfusion Scan: A radioactive agent is injected into the bloodstream and the presence of the radioactive agent in the brain is measured. Absence of the radioactive agent in the brain will confirm the absence of blood flow in the brain.