In a first-of-its-kind operation, surgeons put a patient in suspended animation

Freezing a person’s body to “pause” their life functions isn’t science-fiction any more. Earlier this month, surgeons said they had managed put a living human being into “suspended animation” for the first time in history.

Medically termed emergency preservation and resuscitation or EPR, the suspended animation technology is designed to help trauma patients whose heart has stopped.

“We know that these patients have a less than one in 20 chance of living,” explained Professor Samuel A. Tisherman, who led the research and preclinical work for the technology.

His interview is available online in a video posted by the University of Maryland School of Medicine in Baltimore, US, where he works.

What is a suspended animation?

People with extreme acute trauma usually die within minutes. Those who have excessive bleeding, like gunshot victims, can have a cardiac arrest. In such patients, according to Professor Tisherman and his team, suspended animation, or EPR, can buy time for surgeons to find the source of the bleed and fix it.

How does it work: by inducing therapeutic hypothermia. Surgeons inject “ice-cold salt-water solution” into the aorta to rapidly cool down the heart and brain. The idea, Professor Tisherman explained further, is that by inducing hypothermia, surgeons can decrease the body’s need for oxygen at the cellular level. When cells get the (lower) amount of oxygen they now need, they don’t die as quickly.

Current protocol

Professor Tisherman said that when people come into trauma centres with a gunshot wound or a stab wound but no pulse, doctors have to put a breathing tube down their throat and start manual compressions on their chest, medically termed as Cardio Pulmonary Resuscitation (CPR). They even put large intravenous catheters inside the patients to supply lots of fluids and blood. But this rarely works.

Doctors sometimes open the left side of the chest and massage the heart directly to help with blood flow. Clamping the aorta (the largest artery) makes sure that blood flows into the heart and the brain.  

But again, this is rarely enough. Unfortunately, after all these endeavours, only one in 10 of these trauma patients survives.

How does EPR work?

Our cells and tissues need oxygen to generate energy. When the body suddenly loses a lot of blood (that carries oxygen), tissues start to die. EPR helps in decreasing the need for oxygen in tissues for a limited period.

For EPR, doctors inject an ice-cold saline solution into the aorta at the rate of one gallon (or 3.75 litres) a minute. This rapidly cools down the person’s body to about 50 degrees Fahrenheit (or 10 degrees Celsius) and gives the surgeons time to take the patient to the operating room to control the source of bleeding and treat injuries.

According to Professor Tisherman, it takes 15-20 minutes to accomplish cooling, then 45 minutes to 1 hour for the doctors to stop the bleeding. To restart the circulation, surgeons use a heart-lung machine to get the blood pumping again. Rewarming the body and starting up the circulation might take another one to two hours.

The surgeons also keep a close eye during this time to make sure that the patient wakes up and doesn’t go into multi-organ failure after rewarming. Another potential complication they look out for is that flushing the blood back into the body after a break can lead to reperfusion (re-oxygenating) injuries, in which a series of chemical reactions damage the cells of the body.

First human trial

After being tried in labs and on pigs in animal trials, EPR was recently tried on a human. Next, Professor Tisherman said that his team plans to take 10 patients in the human trial phase for results to be declared later.

To be sure, this kind of trial poses its challenges: because the people who are fit for the trial are brought into the centre in extremely critical conditions, they cannot be asked for individual consent before the procedure. However, Professor Tisherman said that his team have reached out to the local community in the vicinity of the trauma centre, to make them aware of the procedure and the trial, to keep them in the know and to take their feedback.

The professor added that children, pregnant women, people over the age of 65 and people with blunt trauma, car accidents or falls would not be included in the trial.

If the trials are successful, Professor Tisherman hoped, it could change the way we revive critical trauma patients.

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