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Brain death

thedeathclock on 04/10/2008 at 3:44am (UTC)

Brain death
Brain diagram showing brain stem
Brain diagram showing brain stem, upper and lower brain. Courtesy of the Australian Museum Research Library

Brain death (irreversible cessation of all function of the brain) normally occurs after a stroke, or an impact that causes the brain to swell and push against the skull, preventing blood from flowing to the brain. In the absence of oxygenated blood, brain cells quickly die. The dead cells break down and liquefy. Brain death is quite different from reversible coma (unconsciousness) in which living brain cells remain.

A person can remain permanently unconscious with total or partial brain death. A person with death of only the upper brain (cerebral hemispheres) will not have consciousness, memory, knowledge or thought, but the living lower brain (brain stem) allows the heart to pump, the lungs to breathe and the body to function.

To be legally brain dead, all function of both the upper and lower brain must cease. Because the heart will fail on a brain-dead person, certification of death by brain-death criteria (instead of circulatory criteria) will only be needed when the dead person's body functions are being maintained by an artificial ventilator.

To establish that the brain is dead, certifying doctors must ascertain that:

* there is no evidence of brain function over a period of time
* the loss of function is not a result of drugs, hypothermia (low temperature), hypoglycaemia (low blood sugar) or hyponatraemia (low blood sodium)
* the person has sustained a brain injury sufficient to account for the irreversible loss of brain function. Often this is done by CT scan
* there are no reflex functions associated with coughing, gagging, eye movement, blinking, or dilation of the pupils
* the person makes no attempt to breathe when disconnected from the respirator for several minutes
* during the previous test, the carbon dioxide level of the blood has risen above the point at which breathing is normally stimulated

These tests are frequently repeated after a further 24 hours as an assurance of irreversibility. A flat electroencephalogram, indicating an absence of brain activity is often used for verification.

Where the "dead" person's organs are available for donation, two doctors, neither of whom is caring for a potential organ recipient, must undertake the testing and certification.

If the person has received drugs that might invalidate the testing procedure, or if the head is so badly damaged that the tests cannot be performed, death can be determined by total lack of blood flow to the brain. This is done by inserting dyes (angiogram), or radioisotopes into the blood vessels supplying the brain blood vessels, to ascertain that they do not travel to the brain.

Defining death

thedeathclock on 04/10/2008 at 3:43am (UTC)

* Legal
* Religious and cultural
* Clinical - Brain death

Legal
"In Australian law, death is generally defined as either irreversible cessation of circulation of blood in the body of the person or irreversible cessation of all function of the brain of the person."

National Health and Medical Research Council. This definition applies to all states except Western Australia, which has no statutory definition of death.

Brain death (irreversible cessation of all function of the brain) means death of both the upper brain and brain stem. A person who is brain dead has lost both the capacity to think and perceive, as well as the control of basic body functions. Court challenges to consider upper brain death alone have so far failed, but history suggests that our current definition of death is far from permanent.

In the future it may be possible for individuals to define death for themselves by specifying under what circumstances they want to be considered dead. There is already provision for this in some countries.
Religious and cultural

For the Roman Catholic Church death is the "complete and final separation of the soul from the body". However the Vatican has conceded that diagnosing death is a subject for medicine, not the Church. In 1957 Pope Pius XII raised the concerns over whether doctors might be "continuing the resuscitation process, despite the fact that the soul may already have left the body." He even asked one of the central questions confronting modern medicine, namely whether "death had already occurred after grave trauma to the brain, which has provoked deep unconsciousness and central breathing paralysis, the fatal consequences of which have been retarded by artificial respiration." The answer, he said, "did not fall within the competence of the Church."
"It remains for the doctor and especially the anaesthesiologist, to give a clear and precise definition of "death" and the "moment of death" of a patient who passes away in a state of unconsciousness."

Pope Pius XII.

Followers of religions like Zen Buddhism, and Shintoism believe that the mind and body are integrated and have trouble accepting the brain death criteria to determine death. Some Orthodox Jews, Native Americans, Muslims and fundamentalist Christians believe that as long as a heart is beating--even artificially, you are still alive.

Defining death

thedeathclock on 04/10/2008 at 3:43am (UTC)

Signs of death

thedeathclock on 04/10/2008 at 3:41am (UTC)

"Lend me a looking glass;
If that her breath will mist or stain the stone,
Why then she lives."

King Lear Shakespeare

Among classical Greek and Roman societies the signs of death were the absence of a heartbeat and breathing, and the onset of putrefaction. In medieval times a candle was held to the mouth - a flicker of the candle was shown as a sign of life.

However, these signs were rejected by anatomist Jacques-Benigne Winslow in 1740, who recommended that resuscitation should be attempted on seemingly lifeless patients by stimulating various parts of the body with the "juices of onions, garlic and horse-radish, . . . whips and nettles, ... and by hideous Shrieks and excessive Noises." Pins were also inserted under the toenails.

In 1742 John Bruhier documented fifty-two examples of supposed live burial, in his book Dissertation de l'incertitude des signes de la mort, This fed the public's fears of premature burial, and placed growing pressure on doctors to come up with more reliable 'signs of death' as a diagnostic tool. German doctors concluded that putrefaction was the only reliable indicator of death. A number of cultures include an interval between death and disposal of the body that allows time for putrefaction. For example, the leichenhäuser (corpse houses) of 19th century Germany provided a place where 'corpses' were kept under surveillance until putrefaction was apparent.

The 'Safety Coffin' highlights people's uncertainty about pinpointing the moment of death and their fear of being buried alive. The safety coffin provided a means for "deceased" to signal the world above for help and salvation.

More immediate and drastic techniques have also been employed to ensure that the dead were really dead. Some people requested in their wills, that their head be severed, or their heart be pierced prior to burial as a measure to ensure they were truly dead. The invention of the stethoscope in 1819 removed the need for these extreme measures.

But medical intervention has also increased uncertainty. The invention of the artificial respirator in the 1950s meant that the cells of the body could be kept alive in the absence of a natural heartbeat. By 1968 when the first heart transplant was performed, it was already clear that there needed to be a diagnosis for death that was not based on heartbeat. A committee based at the Harvard Medical School in the USA, came up with a diagnostic criteria for death called brain death criteria.

The face of death

thedeathclock on 04/10/2008 at 3:40am (UTC)

Death masks show the subject's facial expression immediately after death. It was important to make death masks quickly, before the features became distorted. Death masks were used for a number of reasons - as a tool for sculpture or effigy making, or as objects of veneration.

The image to the right image taken c1860 shows The Australian Museum's collection of death masks. The collection included the mask of 'Bold' Jack Donohue, better known as 'The Wild Colonial Boy. In 1897, the masks were given to the Anatomy Museum at Sydney University, but have since disappeared.

In 19th century Australia, plaster casts of criminals were commonly used in the study of phrenology. Phrenologists divided the head into 35 areas called 'faculties'. Bumps or depressions in these areas revealed a person's strengths, weaknesses and motivations. The extremes of society - the exalted and lowly - were of especial interest. By studying the heads of criminals, phrenologists believed they could prove the existence of a criminal type or class.

What is death?

thedeathclock on 04/10/2008 at 3:38am (UTC)

What is Death?

Throughout the world, death and all the rituals that surround it are steeped in taboos. Even in cultures where death is celebrated and embraced, certain restrictions on clothing or food can apply after a death.

In Australia today, many people find being in the presence of death frightening and unwelcome. Death is often hidden, sanitised and orderly. The Australian Museum has developed this website to accompany an exhibition designed to help explore some of the taboos surrounding death and explain what happens to our bodies when we die.

Death begins when the heart stops beating. Deprived of oxygen, a cascade of cellular death commences, beginning with brain cells and ending with skin cells. Death is a process rather than an event. Specifying the moment of death usually involves deciding on a point from which there can be no return.

In most Australian states, the current law describes death as:

'either irreversible cessation of circulation of blood in the body of the person or irreversible cessation of all function of the brain of the person'.

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