For the first time, doctors have placed people in suspended animation in an effort to repair traumatic injuries that would otherwise kill them.
Image Credit: Gorodenkoff / Shutterstock.com
The team’s technique, which is officially called emergency preservation and resuscitation (EPR), was described at a symposium on Monday at the New York Academy of Sciences.
The technique is being tested as part of a trial in the US involving people who arrive at the University of Maryland Medical Center in Baltimore with an acute trauma such as a stab wound or gunshot and who have had a cardiac arrest.
The team hopes to announce the full results by the end of 2020
Samuel Tisherman from the University of Maryland School of Medicine and his team of medics have used the technique on at least one patient, but they have not yet revealed how many people have survived as a result.
Tisherman, who called the procedure “a little surreal” when they first performed it, says he is aiming to announce the full results by the end of 2020.
On arrival at the medical center, the patients’ hearts would have stopped beating, and they would have lost more than 50% of their blood. Doctors would usually only have minutes to operate, and patients would usually have a less than 5% chance of surviving.
How does EPR work?
In the case of EPR, the patient’s body is rapidly cooled to around 10 to 15°C using ice-cold saline to replace all of their remaining blood. The patient, who’s brain is almost completely inactive and who would otherwise be considered dead, is then disconnected from the cooling system and taken to the operating theatre.
EPR buys medics two hours to perform surgery and repair the patient’s injuries before their body is warmed back up, and their heart is restarted.
At a normal body temperature of around 37°C, cells rely on a constant supply of oxygen to be able to produce energy. Once the heart is no longer beating, blood stops transporting oxygen to cells, and without oxygen, the brain only has a few minutes before it becomes irreversibly damaged.
However, when the body and brain are cooled, all the chemical reactions that take place in cells are stopped, meaning the cells do not require as much oxygen.
The team’s plan
The team’s plan is to compare ten people who have undergone EPR with ten who could not receive the treatment because the correct team of medics was not present at the hospital at the time they were admitted.
The US Food and Drug Administration approved the trial, which is made exempt from requiring patient consent based on the injuries probably being fatal and an absence of any alternative treatment options.
Tisherman and colleagues discussed the trial with the local community and advertised it in newspapers, with adverts directing people to a website where they could choose to opt-out.
What prompted Tisherman to investigate body cooling?
Tisherman became interested in trauma research early on in his career when he saw a young man get stabbed in the heart during an argument over bowling shoes.
“He was a healthy young man just minutes before, then suddenly he was dead. We could have saved him if we’d had enough time,” he says. The incident prompted Tisherman to start exploring ways in which cooling the body might buy surgeons more time to save a patient.
Animal studies had previously shown that pigs with acute trauma could have their bodies cooled for three hours before being resuscitated. Tisherman thought it was time to test the body cooling in patients.
Now we are doing it and we are learning a lot as we move forward with the trial. Once we can prove it works here, we can expand the utility of this technique to help patients survive that otherwise would not.”
Samuel Tisherman, University of Maryland School of Medicine
Buying more time to save lives
Tisherman says he would like to stress that the team is not “trying to send people off to Saturn,” but rather “trying to buy ourselves more time to save lives.”
In fact, the length of time that a person can be in suspended animation is not yet clear. As the body is warmed back up, reperfusion injuries can occur in cells. These injuries are caused by a series of chemical reactions that damage cells, and the longer cells are missing oxygen, the more damage occurs.
Tisherman says it may be possible to minimize this damage using drugs that would extend the time for which cells are suspended, but that the team has not yet identified all the causes of reperfusion injuries.
Ariane Lewis, director of the neuro-critical care division at NYU Langone Health, says she thinks the trial is important but that it is only the first step.
“We have to see whether it works and then we can start to think about how and where we can use it,” she concludes.
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