Most of the time, it’s easy enough to tell if someone is dead: There is no heartbeat, no breathing, the skin turns pale, and the eyes lose their life.
The process can be sudden, like when someone suffers a traumatic injury, or it can take days, weeks, or months, as a person slowly declines from an infectious disease or chronic illness.
Yet, the final result is the same. Dead is dead.
But death isn’t always so black-and-white. What if the heart is still beating, but the brain has ceased functioning? What if you can see the chest rising and falling, but there is no response when you shine a light in a patient’s eyes?
Even physicians struggle with these distinctions, to the point where there have long been two distinct forms of death: Brain death and cardiac death. The definitions can also vary, even from province to province.
But newly published Canadian guidelines aim to end the confusion, making clear that in the end, the functioning of one organ – the brain – matters more than any other.
“It’s important to understand that cardiac death is indeed brain death, since the arrest of circulation stops brain blood flow, which in turn leads to the rapid loss of brain function,” says Dr. Sam Shemie, a cardiovascular health researcher at the Research Institute of the McGill University Health Centre.
He led the exhaustive process to produce the Canadian Clinical Practice Guidelines on Brain-Based Definition of Death.
Those guidelines define death as such: “the permanent cessation of brain function (i.e., brain function is lost, will not resume spontaneously, and will not be restored through intervention) and is characterized by the complete absence of any form of consciousness (wakefulness and awareness) and the absence of brainstem reflexes, including the ability to breathe independently. This can result from cessation of blood circulation to the brain after circulatory arrest and/or from devastating brain injury. Residual brain cell activity that is not associated with the presence of consciousness or brainstem function does not preclude death determination (e.g., posterior pituitary antidiuretic hormone release, temperature control, or cellular-level neuronal activity). Death cannot be declared if there is any level of consciousness remaining and/or residual brainstem function regardless of how diminished.”
It’s quite a mouthful, but the key message is this: When the brain completely stops working, the person is dead.
Technology has made rescuing people from death a lot easier. Mechanical ventilation can keep the lungs working; dialysis can do the work of the kidneys; the heart can stop and be restarted with CPR or a defibrillator; organs (even the heart) can be removed and replaced with transplantation.
But the brain cannot be replaced or artificially supported. When blood stops flowing to the brain, you can’t survive more than a few minutes. You’re dead.
Having a clear definition of death matters, not only in medicine, but legally speaking. It is especially important for ensuring the ethical practice of organ donation.
There is enormous complexity here, which is why, in addition to the main guidelines, the Canadian Journal of Anesthesia has published a couple dozen related articles.
Around the world, there have been high-profile cases where families have contested physicians’ declaration of death. In Canada, two cases stand out. The first occurred in September, 2017, when 27-year-old Taquisha McKitty overdosed and was declared dead six days later, but was kept on life support for 16 months while her devout Christian family fought a court battle to prevent doctors from taking her off it. That same month, 25-year-old Shalom Ouanounou suffered an asthma attack that left him on life support for six months; his religious family also launched an injunction to keep him in hospital.
In both cases, the courts rejected the families’ pleas to overrule physicians, but Ms. McKitty and Mr. Ouanounou eventually died “naturally” (i.e. their hearts stopped) before life support was discontinued. Still, both patients occupied badly needed intensive care beds for months at great expense.
The new guidelines on brain death remind physicians to respect patients’ and families’ religious beliefs but that ultimately, it’s science that matters.
All this would be easier if the public understood the mechanics of death. The experts even suggest that, in contested cases, families be invited to witness the testing of brain function, which can show that blood (and hence oxygen) has ceased travelling to the brain, and there is no brain activity.
This won’t make losing a loved one any easier. But it could provide peace of mind – and that’s what these new guidelines are really all about.
André Picard