Brain death

Brain death is the state in which the brain, brainstem included, has irreversibly stopped working, while breathing and circulation are kept going by machines alone. Consciousness will not return, spontaneous breathing will not come back, and there is no way back. In medicine and in law this is not a very grave condition and not a deep coma: it is the confirmation that the person has died, and what the machine sustains from then on is the body, not the life. This text is written for the relatives who have been told those words in an intensive care unit, so that they can understand what stands behind them and what happens next.

Why the heart beats although the person has died

The hardest thing for a family is the gap between what the doctor says and what the eyes can see. The chest rises, the monitor shows a rhythm, the skin is warm, the hands do not look like the hands of someone who has died.

The explanation is simple. The heart needs no instruction from the brain: it has its own pacemaker and, as long as oxygenated blood reaches it, it keeps contracting. The oxygen comes from the ventilator, which pushes air into the lungs by itself, whether or not any urge to breathe exists. Everything the family sees is produced by the equipment. Take it away and, within minutes, both breathing and heartbeat stop, because the command to draw breath will no longer come from anywhere.

For the same reason brain death is only ever confirmed in someone on a ventilator. Without intensive care the situation does not arise.

What the brainstem is responsible for

The brainstem is the lower part of the brain, the part continuous with the spinal cord. Every connection between the hemispheres and the body passes through it, and it houses the centres that work without our involvement:

• breathing, meaning the urge to take a breath at all;
• heart rate and the level of blood pressure;
• swallowing, coughing and the gag reflex;
• the pupils' response to light and the movements of the eyes;
• maintaining wakefulness, the very foundation without which consciousness is impossible.

Death of the brainstem therefore means not the loss of a few separate functions but the disappearance of the very capacity to feel, to be aware and to breathe. While the brainstem is intact, a person can be unconscious yet alive. Once it has died, consciousness is no longer on the table.

What leads to it

At bottom the cause is always the same: the brain went some length of time without oxygen, or was crushed from within by its own swelling. The routes there are:

• severe head injury;
• bleeding inside the brain or beneath its membranes;
• an extensive stroke with mounting swelling;
• cardiac arrest, drowning, suffocation, anything after which the brain went a long while without blood;
• severe infection of the brain or of its coverings;
• a tumour pushing the brainstem downwards.

The skull is a closed box with nowhere to expand. When swelling drives the pressure inside above the pressure at which blood enters the brain, flow stops and the tissue dies all at once, brainstem included.

How it differs from coma and the vegetative state

These three are confused constantly in conversation, and the difference between them is fundamental.

Coma: the person does not come round and the eyes stay closed, but the brainstem works; the pupils respond and breathing may be the person's own. Coma is reversible and people emerge from it.

The vegetative state: the brainstem is preserved while the hemispheres are severely damaged. The person is awake, opens their eyes, has cycles of sleep and wakefulness, and usually breathes unaided. But there are no signs of conscious awareness: the gaze does not follow and there is no response when spoken to. Improvement is possible, particularly in the first months, and the earlier flickers of response appear, the likelier it becomes.

Brain death: no wakefulness, no brainstem reflexes, not one attempt to breathe. Recovery does not happen at a month or at a year.

The reverse matters too: accounts of someone waking after being declared dead almost always concern a coma or a vegetative state that the retelling labelled brain death. A properly established diagnosis is not reversed.

How the diagnosis is made

The procedure is rigid precisely because an error is not permissible.

First, everything capable of imitating the picture is excluded: drugs and poisons, among them sedatives, barbiturates, painkillers of the opioid group and muscle relaxants; a low body temperature; very low blood pressure; and severe derangements in the blood tests, such as a profound lack of thyroid or adrenal hormone and abrupt shifts in sodium or glucose. Until every one of these is cleared, testing does not begin. Beyond that, the cause of the damage must be clear and its irreversibility established from the imaging and from the history of what happened.

Next the brainstem reflexes are checked: a torch is shone into both eyes, the cornea is touched, pressure is applied above the eyebrow, cold water is put into the ear canal (normally this makes the eyes move), and a catheter is passed into the breathing tube to provoke a cough. Separately there is the disconnection test: the person is left off the ventilator for a short period while it is watched whether a single attempt to breathe appears as carbon dioxide in the blood climbs to the level that would normally compel breathing.

The conclusion is reached by two doctors qualified to do so, neither of whom has any link with the transplant team. The whole series is carried out twice to rule out chance. If the person's condition makes proper reflex testing impossible, for instance because of facial injuries, further studies are added that show whether blood is reaching the brain at all.

One thing deserves separate mention because it frightens relatives most. After brain death has been confirmed, the arms or legs sometimes flex, the shoulders lift, the torso jerks. These are reflexes of the spinal cord, which is capable of acting on its own. Such movements have nothing to do with the brain and do not change the diagnosis.

The conversation about donation

Once brain death has been confirmed, the organs may be suitable for transplantation, and doctors are obliged to raise the subject. That conversation is handled by a separate team, not by the one that made the diagnosis, and this separation holds everywhere transplantation is carried out at all.

The rules on consent are arranged differently from country to country and must be checked for the particular country. One thing is common to all of them: the decision is always easier if the person said what they thought while alive. When they did not, the choice falls on those closest at the worst possible moment, and nobody has the right to hurry them or to reproach them. A refusal changes nothing about how the body and the family are treated.

Online consultation

A diagnosis of brain death is made only at the bedside and only by protocol; online it is impossible. But a doctor at a distance can do something else, and often the thing needed right now: go calmly through the wording of the notes and the words spoken in intensive care, explain the difference between coma, the vegetative state and brain death, suggest what to ask the team looking after your relative, and help you understand what you are entitled to in the conversation about donation.

This material is for information only and does not replace medical advice.