Medical wisdom has long held that when treating cardiac arrest, speed is of the essence. “The thinking in cardiac arrest was that when blood flow stops, the chances of resuscitation is very low and can only be done if a patient is aggressively treated within several minutes,” explains Dr. Benjamin Abella, clinical research director at the University of Pennsylvania’s Center for Resuscitation Science. But what if what we actually need is to slow things down? Abella’s work shifts from a traditional focus on time toward the less explored terrain of temperature. He and his partners are pioneering the use of “therapeutic hypothermia”: the controlled cooling of cardiac-arrest patients to 32-34° C, to slow hearts and save lives.
Dr. Dan Waters, a cardiovascular surgeon in Des Moines, Iowa, was among the first to witness how useful hypothermia can be. Fifteen years ago, a man who had fallen through the ice was brought into his ER. “He met all the criteria for being dead,” Waters says: no heartbeat, no spontaneous respiration, no blood pressure, and presumably no brain activity. But, although the patient had been without a heartbeat for an hour or two, he wasn’t dead at all. The case was meaningful, says Waters, because it demonstrated, albeit accidentally, “the power of the cold.”
It’s that force—the cold—that Abella’s team has harnessed. Old canons of medicine insisted that people “died” four or five minutes after their hearts stopped. And it’s true that some cells do die in that time. But many more live. According to Abella, what kills cells is not the cardiac arrest itself, but what comes next: the rapid restarting of the heart using defibrillation and shots of epinephrine. “The sudden rush of blood back to the tissue is actually very injurious,” he explains. First, the flood of blood can make the immune system go “haywire,” causing full-body inflammation. The damage continues at the level of mitochondria. The tiny “powerhouse” organisms, believing the cell to be damaged, initiate a process of “apoptosis,” or self-destruction. And so the very thing that patients need most—oxygen—ends up killing them.
Dr. Lance Becker, director of the Center for Resuscitation Science, says cold, used hand in hand with CPR and defibrillation, resolves that fatal paradox. “We don’t turn [the patient] into an ice cube,” he says. But a few degrees cooler is enough to slow the cells’ oxygen uptake and prevent mitochondrial suicides. How it works is still a mystery. “We have more theories than we have ways of cooling,” Becker concedes. But, Abella adds, “like many things in medical science . . . if it works it works, and sometimes understanding follows use.” Both have seen many patients who were “technically dead for 15 or 20 minutes” return to normal lives after being cooled.
But six years after the American Heart Association endorsed cooling, there are still kinks to be worked out. First, there’s no set protocol for how to cool. While some hospitals lead the way with cooling catheters or external wrap devices, others work with, literally, bags of ice. There’s also the issue of time. The sooner the body can be cooled, the better, but the process can take hours. That’s why Becker is working on a cooling “slurry” that could be injected right into the bloodstream. “Do you have 7-Elevens in Canada?” he asks. “Have you ever got a slushy? This is a bit like that.” The fluid contains ice particles that start cooling instantly. And because it’s portable, the slurry could be used by paramedics to effect hypothermia at the scene.
Many hospitals, especially in Europe, have been cooling for years. But, for now, hospitals here have been shy to embrace the technique. Dr. Ian Stiell, chair of the University of Ottawa’s emergency medicine department, estimates that while it’s more popular than it used to be, “less than a quarter [of Canadian hospitals] have a formal protocol” for cooling. And he says Health Canada is “staying neutral on the issue.” That sluggishness is “remarkable,” says Abella, “considering how strong the data are in support of hypothermia.”
A report in the journal Circulation shows hypothermia is as cost-effective as conventional treatments. And current standards of care are hardly flawless. In Canada, survival rates for out-of-hospital cardiac arrest hover around five per cent. Becker wonders if hypothermia is unpopular because it’s “troublesome.” It requires the participation of nurses, ER physicians, cardiologists, neurologists and engineers. Once it’s induced, a hospital is committed to 24-hour monitoring. “It requires a system of care. Unfortunately, many hospitals have not worked out their systems.”
Still, hypothermia’s tireless activists are confident. “For years, cardiac arrest was synonymous with a death sentence,” Abella explains. “That mantra has been changed.” The doctor laughs off charges that he’s attempting the impossible: trying to treat the dead. It’s more like “trying to raise the dead,” he says, and he’s only half joking.
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