Posted on Feb 05, 2020, 1 p.m.
Extreme cold is being utilized to bring humans back from the brink of death; after being shot or stabbed and losing half of your blood there is only a 5% chance for survival, but this experimental procedure may help to increase these dire odds.
It is not unheard of for victims of cold water drownings to be successfully resuscitated, this led to Mads Gilbert coining the phrase “nobody is dead until warm and dead” after resuscitating a woman who fell through ice and her temperature dropped to 13.7C. Incidents such as these also raise questions about the likelihood of the science of cold helping to bring humans back from the brink of death.
Trauma surgeon Samuel Tisherman is putting the science of cold to the test, rather than warm patients up he is cooling them down. In 2019 a patient was placed into suspended animation for the first time by Tisherman and his team at the University of Maryland School of Medicine. The procedure described in New Scientist details how the patient was rapidly cooled down to 10-15C which temporarily stopped vital functions to put the patient into a state somewhere between life and death. The team was investigating whether stimulating the same situation as drowning in cold water in a hospital setting could help patients.
Tisherman explains, “There are numerous reports of people who drown in cold water and do fine, because they cool fast enough to protect the brain and heart.”
During serious injuries that cause cardiac arrest such as gunshot or stab wounds the patient has grim odds of survival, once that unfortunate person has lost half of their blood there is only a 5% chance of survival, irreversible brain damage within 5 minutes, and permanent heart failure after 20 minutes which leaves surgeons a short window to operate in.
“Despite very aggressive, very active things that we do to try to save these people, like giving them blood and opening the chest, it just doesn't work,” says Tisherman. “Surgically, it's a race against time to get the bleeding stopped so you can resuscitate the person before their internal organs are damaged irreversibly by not having enough blood flow.”
Animal studies have shown that turning down the heat is associated with a better chance of survival; cooling effectively slows time down as at normal body temperature cells need a constant supply of oxygen, cool the body down to 15C and the brain can survive for at least two hours, according to Tisherman.
Applying this to humans is not an easy task, to do so the patient’s remaining blood must be drained and replaced with ice cold saline solution. Once cold enough the patient is moved to the operating theatre; the state of suspended animation affords surgeons more time to perform life saving operations before reintroducing blood, slowly warming the patient up, and restarting their heart.
At the moment Tisherman is declining to release details on success/failure rates for this desperate procedure which has been called EPR: Emergency Preservation and Resuscitation. Tisherman is also unclear as to how long a person can be kept in this state of suspended animation with causing damage to vital organs when the patient is returned to normal body temperature.Tisherman and his team are collecting data for an FDA approved trial which will investigate whether this method can eventually be used to help acute trauma patients.
It is a long road with many details to iron out before suspended animation will become commonplace in the medical field. Most can agree that this idea makes sense in principle, but many also wonder how feasible the procedure is, especially when you consider that blood will not be able to clot at the proposed temperatures.
According to Karim Brohi, head of research at the Centre for Trauma Sciences at Barts Hospital in London, “There's all sorts of problems with it because in order to operate we need to have blood that clots around stitches and things,” he points out. “And even if you can reduce somebody's temperature to that level, how do you fix them after that and how do you safely rewarm them?”
While Brohi agrees with the idea in principle he has many questions/concerns, but adds that the procedure is not that far off from another performed regularly on some patients with brain injuries that relies on mild hypothermia to reduce tissue damage.
“If you've got a cerebral aneurysm in a critical case, the patient can be put on bypass, and the machine cools their blood down to stop their heart. You do the surgery, warm them back up and the heart starts again,” Brohi reveals. “But the difference there is that it's a controlled procedure done over some period of time, with the patient's own blood in their system.”
When a trauma patient is brought into an emergency room, time is not on anyone’s side. If doctors can get the body to slow down biological processes by using this process or another it may create the time needed to save lives. Tisherman is focussed on using cooling for EPR, but others are also looking at the cold, some are looking at the animal kingdom to see if hibernation can be of use to human healthcare.
Vladyslav Vyazovskiy, a neuroscientist at the University of Oxford suggests that human can potentially hibernate, and is hoping that scientists will be able to figure out how humans can enter torpor to reduce metabolism before reducing body temperature without having any harmful lasting consequences to more safely induce a state of suspended animation.
“The endpoint effect is similar to suspended animation and may be indistinguishable to some extent but I think there is an important distinction about how this is achieved,” he points out. “Animals know the trick and we don't.”
Elon Musk, CEO of SpaceX has announced that he has plans to send one million people to Mars by 2050 to build cities and create jobs. This is a bold claim, to even send a fraction of that within the next few decades will be an extreme challenge. If there was a rocket that can carry people to Mars, what would they do in that tiny space for at least 6 months? Synthetic hibernation could help to reduce the engineering demands for long space travel durations and make the experience less stressful, but the strain of doing so would also likely cause problems when they reach the destination.
“You don't put healthy people that have to jump out and do the best work of their lives the day they land on Mars into this state that is basically only used for people about to die,” says Sandy Martin, from University of Colorado Denver, who studies the molecular mechanisms responsible for torpor. “But the hibernator really does just pop out of its burrow and get going with life. So if we could do that, it would be huge.”
“We have no idea how animals enter into torpor state,” says Vyazovskiy. “We can produce a very artificial physiological state by injecting some drugs that prevent you from regulating your body temperature, and then you would cool down and this would look pretty much like hibernation. But this is very dangerous,”
“It’s very tricky to take a normal-sized person, and cool them down to 15C,” admits Tisherman. “It would be amazing if somebody came up with a drug that could lead to the same effect.”
Tisherman is dedicated to seeing his project through trials to demonstrate the feasibility of the procedure on patients that otherwise would have died. He is working on long term troubleshooting to expand the procedure to other hospitals, with the goal of getting 10 patients to undergo the procedure to compare with 10 controls. Tisherman claims once this number is reached he will share his work/findings, including all of the numbers with the public.
This procedure is pushing the current boundaries of trauma medicine to save lives of those who have a very low chance of recovery, who otherwise likely would have died. According to Tisherman, “The response so far has been: ‘things are so bad right now with all we’re doing in trauma medicine, that this is worth looking at’,” he says. “People might think it’s crazy — but it’s so crazy it just might work.”
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