Did Doctors Put Humans in Suspended Animation? The EPR Trial

Originally published 2020-05-19.

Not in the science-fiction sense. In November 2019, trauma surgeon Samuel Tisherman of the University of Maryland School of Medicine told New Scientist that his team had begun using a technique called emergency preservation and resuscitation (EPR) on patients. Doctors replace a dying patient's blood with ice-cold salt solution, rapidly cooling the body to around 10–15°C, compared with a normal 37°C. That slows the body's need for oxygen enough to give surgeons more time to repair catastrophic injuries. Nobody was frozen, and the aim is not space travel. It is to save people who would otherwise die on the operating table within minutes.

What doctors in Maryland actually did

EPR is designed for a very specific and desperate situation: a patient with a severe penetrating injury, such as a gunshot or stab wound, whose heart has stopped from blood loss. In that situation, standard resuscitation rarely works. The heart has nothing to pump, and the brain begins to suffer permanent damage after only a few minutes without oxygen.

In the EPR approach, as described in reports at the time, a cannula is placed in the aorta, the body's main artery, and large volumes of cold saline are pumped in, replacing the blood and cooling the brain and organs. With the body chilled, surgeons have up to about two hours to find and repair the bleeding. Then the patient is reconnected to a heart-lung machine, warmed and given blood again, with the hope that the heart will restart.

Tisherman told New Scientist that the procedure had been carried out on at least one patient, but did not say how many people had been treated or whether they survived. He said full results would be published later.

Humans are being put into suspended animation for the first time using a process which cools the brain and replaces the blood with an ice solution. The process has been performed in trials at the University of Maryland. pic.twitter.com/3m9bls0pB4

— GIANT FREAKIN ROBOT (@GFRobot) November 21, 2019

Why cooling buys time

Every cell in the body needs oxygen to keep running. When blood flow stops, the brain is the first organ to fail, which is why surgeons have so little time in cases of cardiac arrest after trauma.

Cold slows chemistry. As body temperature drops, the rate at which cells use oxygen falls sharply, so tissues can survive much longer without circulation. Doctors already use milder cooling, known as therapeutic hypothermia or targeted temperature management, after some cardiac arrests and in certain heart and brain operations. Some complex surgery on the aorta is performed in deep hypothermic circulatory arrest, with the patient cooled and blood flow stopped for a period.

EPR takes the idea further and applies it to emergency trauma, where there is no time for planning. Its goal is not to stop life indefinitely but to hold it steady for an hour or two.

Decades of research behind it

The concept grew out of work at the University of Pittsburgh, home of the resuscitation centre named after Peter Safar, the Austrian-born anaesthesiologist often credited as a pioneer of modern CPR. Tisherman co-authored a 1996 review titled "Suspended animation for delayed resuscitation," which set out the idea for trauma care.

Animal studies followed. In 2005 Safar Center researchers reported placing dogs into a state of clinical death by draining their blood and circulating a cold solution; after about three hours, the blood was returned and most of the dogs recovered without obvious brain damage. In 2006 a team at Massachusetts General Hospital reported similar work in pigs with severe injuries, cooled to about 10°C, with a high success rate. Those results persuaded researchers that a human trial was worth attempting in patients who otherwise had almost no chance.

Consent, ethics and the FDA

Patients who need EPR are unconscious and dying, so they cannot agree to take part in research. In the United States, the Food and Drug Administration allows a narrow exception from informed consent for emergency research when a condition is life-threatening, current treatments are unsatisfactory and there is no realistic way to ask the patient or family in time. Researchers must consult the community beforehand, inform the public and have the study overseen by an ethics board.

The Maryland trial was approved under these rules, which is why some news stories at the time said it went ahead "without consent." That phrase is accurate in a narrow sense, but it describes a regulated framework with safeguards, not doctors acting alone.

Tisherman explained his motive with the memory of a young stabbing victim who died because there was simply not enough time to operate. As he put it: "We're trying to buy ourselves more time to save lives."

Myths about suspended animation

• "They froze people." No. Water freezes at 0°C, and ice crystals destroy cells. EPR cools the body to roughly 10–15°C, which is very cold for a human but nowhere near freezing.
• "It is a first step to cryosleep for astronauts." Tisherman was blunt: "we're not trying to send people off to Saturn." The technique works for hours, not months, and depends on an operating theatre and a heart-lung machine.
• "It is now a standard treatment." It is not. EPR was tested as an experimental procedure for a small group of trauma patients, and its benefit depends on trial results.
• "The patient was dead and brought back." Patients had suffered cardiac arrest, but the procedure aims to prevent permanent death of the brain and organs, not to reverse it.

What this could mean for patients

Penetrating trauma remains a major cause of death in young adults, and many of those deaths happen because surgeons run out of time rather than skill. If EPR proves safe and effective, it could change outcomes in a small but important group of patients brought to major trauma centres. It would most likely remain limited to hospitals with specialised equipment and teams trained to start the procedure within minutes.

Questions still need answers: how many patients survive, how well their brains recover, and whether the method can be used safely outside a few research centres. Anyone curious about whether EPR is available in their area, or what it might mean for a relative, should talk to a doctor. The science fiction comparison makes a good headline, but the real story is quieter and more remarkable: a few extra hours that may one day let surgeons save people who are dying today.

Sources: Samuel Tisherman's interview with New Scientist (November 2019); Wikipedia: Suspended animation; Wikipedia: Peter Safar.