National Post (National Edition)
Heart often stops, and restarts, several times while dying: study
After the agonizing decision was made to remove life support, the monitors stayed in place — a catheter in the radial artery in the dying person's wrist to measure blood pressure. Five sticky pads with electrocardiogram leads on the chest and abdomen. Second by second, beat-by-beat, the monitors recorded any signals of a pulse, blood pressure or electrical activity of the heart, all with the goal of answering: when the heart stops, does it stay stopped?
How long should doctors wait to feel comfortable someone is truly, permanently dead before moving to take the organs?
“One of the fundamental principles of organ donation is that you must be dead to donate,” said critical care physician Dr. Sonny Dhanani. Yet anecdotes and stories persist of people “coming back to life” after cardiac arrest, after flatlining without a pulse. “We wanted to provide scientific evidence ….that one is dead before donation,” Dhanani said.
In a study published this week in the New England Journal of Medicine, Dhanani and his co-authors monitored the heart rate, blood pressure and oxygen saturation levels of more than 600 people who had life support withdrawn, from the moment breathing tubes and heart-supporting drugs were removed, to 30 minutes after declaration of death.
The finding, said Dhanani, was surprising: in 14 per cent of cases, the heart stopped and then restarted. Brief bursts of cardiac activity — a heart beat, a pulse — occurred as soon as 64 seconds, and as long as four minutes and 20 seconds, after a period of “pulselessness.”
No one regained consciousness or survived. No one came back from the dead. There was no true circulation. The heart finally stopped, completely. “However, transient resumption of cardiac activity did occur, which suggests that the physiologic processes of somatic (bodily) death after removal of life-sustaining measures occasionally include periods of cessation and resumption of cardiac electrical and pulsatile arterial activity,” Dhanani and his team report.
This wasn't auto-resuscitation, or the so-called Lazarus phenomenon, where in a smattering of cases reported worldwide, the heart spontaneously starts beating, and keeps beating, in people pronounced dead after CPR has ceased.
But the study does support the current “no touch” rule in Canada to wait five minutes after the heart stops before declaring death and proceeding to organ donation. In other countries, hands-off protocols vary from two to 10 minutes.
More than 4,000 people in Canada are awaiting a life-saving transplant. Dhanani worried that there wasn't uniform acceptance of organ donation because of misunderstandings, and “stories, unrelated to organ donation, about people coming back to life following a determination of death.”
Death is determined in one of two ways: brain death, when people are medically and legally dead, but their hearts are still beating, and circulatory death — irreversible loss of heart function. While most organs come from people declared brain dead, about 30 per cent are now retrieved from circulatory death donors.
Once life support is withdrawn, the heart contracts vigorously, and is slowly starved of oxygen and blood. The cells of the muscle begin to die off, blood pressure drops and the heart goes into cardiac arrest. Blood flow stops. There's no perfusion, first and foremost to the brain, but also to the other organs.
Organ donation is a carefully choreographed sequence: Doctors must wait the minimal time before being certain the loss of circulation is permanent, and declaring death, but not so long that the organs deteriorate from lack of blood flow.
The new study, dubbed DePPaRT — or the Death Prediction and Physiology after Removal of Therapy study — was conducted at 16 adult ICUs in Canada, three in the Czech Republic and one in the Netherlands.
It involved 631 people who had suffered a catastrophic illness or accident, and whose grieving families agreed to have their loved one's vital signs recorded after they were removed from life support.
The classic “flatline” of death isn't so smooth. “People don't die right away,” said Dhanani, chief of critical care at CHEO in Ottawa. In the new study, death after cardiac arrest was declared as soon as one minute after life support was withdrawn, but as long as 11 days, five hours and 54 minutes. The median time was 60 minutes. A computer program analyzed each person's waveforms to see when electrical activity and pulse stopped and restarted.
Doctors and staff standing in the ICU said they saw unassisted resumption of heart activity in 13 people.
But when the researchers looked back at the data picked up by the monitors, there was a stop, and then a restart, in 67 of 480 people with complete waveform data.
One systematic review involving a total of 30 people showed a return of cardiac activity in zero to three per cent of people after withdrawal of life support. The longest duration of no pulse before heart activity resumed was one minute and 42 seconds. Also surprising was the electrical activity of the heart can continue for minutes after the blood pressure stops.
“With the heart being an organ that is strong and robust, the idea that it pauses before finally stopping is actually quite reasonable, physiologically, and probably not unreasonable for us to expect it does so.”
He's reassured that no one came back to life. There was no alertness or consciousness. When cardiac activity did restart, it was shortlived, most often for about five seconds.
“I think if doctors and nurses are aware that this can happen, that they'll expect it, they'll counsel families,” Dhanani said.
If heart activity does resume within five minutes, the protocol holds that the “no touch” clock must restart, “which I think adds a layer of safety, and hopefully trust, for the medical community and the public.”
Calgary was the largest Canadian site. Dr. Christopher Doig is head of critical care medicine at the University of Calgary and a study co-author. He's worked in the ICU for almost 30 years, and has been at the bedside of hundreds who have died.
“It's not unusual to see a flatline on the electrical tracing of the heart, followed by electrical beats,” Doig said, “or a minute or so where there was no heart beat, and then a heart beat, again.” He doesn't, however, recall ever seeing it happen as long as 4½ minutes out.
“But this is why this research was important,” Doig said. “It helped confirm that this event can occur, but it also provides reassurance” that, under the current fiveminute rule, “the duration of time is satisfactory. That somebody, when they have their organs recovered, is truly dead.”