Research Briefs, Science & Technology

Determining the criteria for postmortem organ donation

In the past, a person’s death was determined by the absence of breathing and a heartbeat. However, the introduction of the mechanical ventilator has complicated death determination. In patients with severe damage to the brain, breathing stops, which causes the heart to stop beating. Through life support, doctors can now keep a patient clinically alive by mechanically ventilating them with a machine, even if they do not have a functioning brain. 

“When things cannot get better with time or treatment, all life support does is prolong an inevitable death,” Dr. Sam Shemie, an intensive care doctor at the Montreal Children’s Hospital and professor in the Department of Pediatrics at McGill, said in an interview with The McGill Tribune. “When the patient cannot recover, or cannot recover with any quality of life, there is usually a decision with the family to stop life support.” 

In these situations, doctors often bring up the question of organ donation to the patient’s family. 

“Someone’s inevitable death can still help many other people through organ donation, to prevent death for other people,” Shemie said. 

Some organ donations, like kidney transplants, can be performed with no significant impact on a living donor’s health. When it comes to donating vital organs, the “dead donor rule,” an ethical and legal requirement in Canada and the United States, states that the donor must be deceased before their organs are removed. 

Until recently there was no formal scientific study defining when exactly a patient can be considered dead. The “five-minute rule” was the most widely accepted standard, which simply suggests that doctors should wait five minutes after removing the patient from life support before proceeding with organ removal. 

An international study conducted in three countries including Canada was the first to examine the five-minute rule in great detail. Shemie, who is also the senior investigative researcher of the study, described the goals of their inquiry.

“We wanted to confirm that this is a safe waiting period before proceeding to donation,” Shemi said. 

The results showed that out of 480 patients, there were 67 instances where a resumption of cardiac activity was detected, all within a maximum of four minutes and 20 seconds after the removal of life support. 

“At the end of life, the heart can sputter, stop, and restart transiently to a minor degree before it stops completely,” Shemie said. “But as long as we wait five minutes, it is safe. These transient resumptions are of unclear significance.” 

Organ donation is a race against time, as any unnecessary delay increases the risk of unsuccessful transplantation and deterioration of the organs. The study confirmed that five minutes is a safe waiting time.

“Once the heart stops beating, all the organs that can be transplanted start to suffer, so they have to be removed for transplant very quickly,” Shemie said. “We don’t have to wait more, and we shouldn’t wait less.” 

The most common form of organ donation in Canada remains donation from patients who are brain dead, meaning an absence of activity is detected from electrical measurements of a patient’s brain. It is important to distinguish brain death from cardiac death, where the brain may still have some residual function when life support is removed. In the case of cardiac death, the study has shown that waiting five minutes after the removal of the ventilation machine assures that the patient is dead and that it is safe to proceed with organ donation. 

“[The results] just add to the trust of families, doctors, and nurses,” Shemie said. “If any doctor has ever seen the heart restart beating on its own, they might have some questions or concerns about that. We now have answered this question very clearly. Our goal as doctors is to save as many lives as we can [….] Organ donation is really the intersection of the unpreventable death of one person, and the preventable death of many people.”

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