Canadians have decreased their odds of being declared brain dead over the past decade, but better survival rates after brain injuries may also be responsible for a decline in donor organs, according to a study published Monday in the Canadian Medical Association Journal.
From 2002 to 2012, the proportion of brain-injured patients in southern Alberta who deteriorated to neurologic death (brain death) declined from 8.1 per cent to 4.2 per cent – a 50-per-cent reduction, noted study author Dr. Andreas Kramer, a clinical assistant professor at the University of Calgary.
He said the findings are consistent with reports of decreased mortality in brain-injured patients in other regions.
"Brain death is on the decline in Canada," he said.
Neurologic death is clearly defined in Canadian guidelines, Kramer said. It is the irreversible end of all brain activity due to permanent loss of blood flow and oxygen to the brain. It is not the same as vegetative states, in which patients may have partial awareness. And it is unlike ambiguous states of consciousness detected in patients such as Hassan Rasouli, who was kept on life support after the Supreme Court of Canada ruled on Oct. 18 that doctors at Toronto's Sunnybrook Hospital could not end treatment without his wife's consent.
Kramer and colleagues analyzed data from 2,788 Albertans treated for brain hemorrhage and other forms of brain injury. After adjusting statistically for the initial severity of the injuries, they found that even patients with traumatic brain injury were less likely to be declared brain dead over the study period.
Initiatives for injury prevention, including the use of airbags in cars and helmets for cycling and skiing, have likely contributed to the decline in severe brain injuries, Kramer said.
Although traffic accidents account for the largest number of brain deaths, "I think our roads are safer," he said.
Despite consistent population growth in Alberta, traffic-related deaths decreased 24 per cent between 2006 and 2010, according to Alberta Transportation.
Patient care has also improved, Kramer said. An emergency helicopter response team is available to rush brain-injured patients to Foothills Medical Centre in Calgary. Patients are taken to the CT scanner more quickly, and in the intensive care unit, "there's much more emphasis on protecting the injured brain," Kramer said.
The Calgary study established that patients today have a better chance of surviving brain injuries, said Damian Cruse, a postdoctoral fellow at the University of Western Ontario who specializes in severe brain injury. "But that doesn't mean that those patients who would have gone on to brain death [in the past] did well," he said, noting the study did not indicate how many patients progressed to vegetative states.
The decline in brain deaths has led to a decrease in donor organs, said Kramer, who serves as medical director of the Southern Alberta Organ and Tissue Donation Program. Organ donation after neurologic death accounts for about half of kidney transplants, three-quarters of liver transplants, 90 per cent of lung and pancreas transplants, and all heart and small bowel transplants, he said.
In the study, Kramer and colleagues underlined the need for alternatives to organ donation after neurologic death, including donations from living people with healthy livers and kidneys, as well as donation after cardio-circulatory death, the permanent loss of heart function.
Organ donation after cardiac death is controversial because there is a chance the brain may remain conscious after the heart stops – at least for a brief time, Cruse said. An individual could be sedated after cardiac death in preparation for organ transplant, "but it's ethically difficult," Cruse pointed out.
Organ donation after cardiac death is becoming more common in the United States and Britain. Canadians, however, do not share unanimous support for the practice, Kramer said.
Nevertheless, as neurologic death and organ donations continue to decline, he added, eventually, "I think we will see that trend here."