Defining death: when exactly do we die?

From ABC Health and Wellbeing, 6 june 2013:

What is death? On the surface, this seems like a simple question.

After all, if somebody is not breathing, their heart is no longer beating, they are cold, waxy and stiff, then it is possible to say with a fair degree of certainty that they are dead.

If, on the other hand, they are breathing, even talking, moving around, interacting with their environment and generally doing all the things that one would associate with normal activity, they are alive.

So it would seem obvious that there is a distinct line – a point at which anyone would be able to make the judgement that death has happened.

Yet despite our advances in medical technology and knowledge, death has never been harder to define and diagnose. The definition and diagnosis of death varies between countries, states, and sometimes even different hospitals and doctors view death differently.

Defining death would be easy if there was a single, universal moment that delineates the point of transition between life and death, says intensive care specialist from Sydney’s Royal North Shore Hospital Dr Ray Raper.

‘We think there’s a huge difference between being alive and being dead, we think they’re two completely different states and we should be able to recognise the two separately.’

‘In fact, a much better representation is a continuum; a graded box with one end as “being alive” and one end as “being dead”,’ he says.

‘If you look at the domains of the transition between life and death, they’re spiritual, functional, structural and they’re biological, and the most important are the functional ones.’

Life beyond breath

Death used to be the cessation of breathing. As Shakespeare’s King Lear cried in anguish over the body of his beloved daughter Cordelia, ‘Lend me a looking glass; if that her breath will mist or stain the stone, why, then she lives.’

Then in 1628, English physician William Harvey wrote in his ‘An Anatomical Exercise on the Motion of the Heart and Blood in Living Beings’, that ‘the heart is the principle of life’. Therefore, once someone’s heart stopped beating, they were dead.

That was until 1891 when German surgeon Dr Friedrich Maass performed the first recorded successful cardiopulmonary resuscitation on a young boy who had been given too much chloroform during an operation. A stalled heart was no longer a death sentence.

However, the most significant development came during the height of a polio epidemic in Copenhagen in 1952 when anaesthetist Bjorn Ibsen pulled a MacGyver-like stunt and invented mechanical ventilation using little more than a rubber bag, a length of tube and a tank of oxygen.

Now, if someone’s heart and lungs stopped working, their heart could be restarted and a machine could breathe for them until such time as they were well enough to do both independently, or the condition responsible for them being in such a state claimed them permanently.

Defining brain death

Yet while we may be able to restart a heart and artificially inflate lungs, if the brain is damaged beyond a certain point, what remains is, to all intents and purposes, a warm, breathing corpse.

Today, brain death in Australia, the US and many other countries, is defined as cessation of all functions of the entire brain, including the brain stem. In the United Kingdom, brain death is defined as death of the brain stem only.

Even in this state, however, it is possible for the body to maintain control over some key body functions, such as blood pressure, urination and even gestation of a foetus. A person described as brain-dead can even blush and sweat, which raises the question of just where do we draw the line to distinguish between those bodily functions that qualify us ‘alive’ and those that do not.

In the case of cardiac death – when someone’s heart stops beating – defining death is simply a matter of time. Wait long enough, and there will be a point beyond which no medical technology will be able to restart the heart and nor will it be able to restart of its own accord.

No single marker

If it weren’t for organ donation, much of this discussion would be academic. But medical advances now enable organs to be donated not just after brain death but also after cardiac death. This raises the question: how long after a loved one’s heart stops beating can they be pronounced as dead, and their organs removed for donation?

In Australia, that time frame is between two and five minutes. But in the United Kingdom, guidelines mandate observation for a minimum of five minutes.

But, as American paediatric neurologist Dr Alan Shewmon points out, two minutes or five minutes are arbitrary markers, and not based on measurement of any biological parameter that might be used to indicate that ‘death’ has occurred.

“There is no single marker like that or the threshold of anything like that that indicates the difference between life and death,” Shewmon says.

“It’s an ongoing debate because at the time that these patients are declared dead for purposes of organ procurement, in principle they could be resuscitated, but it has already been decided that that would be inappropriate, so they’re not going to be resuscitated. But if they could in principle be resuscitated, then obviously they’re actually still alive. So if they’re really still alive, how can you declare them dead for purposes of transplantation?” Read more.

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