For the half-dead arriving at hospitals, like the unfortunate who suffer gunshot wounds or lose a lot of blood some other way, there’s very little doctors can do. There are so little life saving procedures and surgeries that can be performed, and doctors need their patients at least a few more hours to be alive for most of these to work. It can be frustrating, but if doctors at UPMC Presbyterian Hospital in Pittsburgh, Pennsylvania are right, this all may change and a new, bold and frightening at the same time procedure might become common in operating rooms all around the world. This is suspended animation.
Half past dead
The procedure involves replacing all of a patient’s blood with a cold saline solution, which rapidly cools the body and stops almost all cellular activity. It seems counter intuitive to empty all the blood in a person’s body because it lost too much blood in the first place, but according to the physicians it might work.
“We are suspending life, but we don’t like to call it suspended animation because it sounds like science fiction,” says Samuel Tisherman, a surgeon at the hospital, who is leading the trial. “So we call it emergency preservation and resuscitation.”
It might work because the cold saline solution effectively cools the body putting it in a new state, where some structural problems that arise at normal body temperature (37 °C) can be solved more easily. For instance, at normal temperature if blood stops flowing in the body following heart failure, then valuable oxygen can’t reach the cells who need it to produce energy. Without oxygen, the most valuable cells in the human body, the brain cells, stop functioning and death follows, and it only takes 5 minutes of oxygen deprivation.
At lower temperatures, cells need less oxygen to produce energy, which in turns slows down all chemical reactions. This is why sometimes people who fall into icy lakes can be revived even half an hour after they stop breathing. In normal conditions they would have been long dead, but because the body first entered hypothermia, the brain still continued to function.
This isn’t exactly new information. Doctors have known this for a long time, which is why before some surgeries ice packs are placed on the body and the blood is circulated through a cooling system. This process takes time and preparation however. If a patient barges through the hospital door more dead than alive, there’s little surgeons can do.
“If a patient comes to us two hours after dying you can’t bring them back to life. But if they’re dying and you suspend them, you have a chance to bring them back after their structural problems have been fixed,” says surgeon Peter Rhee at the University of Arizona in Tucson, who helped develop the technique.
The real innovation comes into play here. First cold saline solution is flushed through the heart and up the brain, where oxygen is most critical. Doctors do this by clamping the heart’s lower region while a catheter is placed into the aorta to carry the saline. Later, the clamp is removed so the saline can be pumped throughout the body. The whole technique, which is a lot more complicated than it sounds, still takes only 15 minutes and drops the patient’s body temperature to 10 °C. There’s no blood in the body, no breathing, no brain activity – the patient’s clinically dead. It’s incredibly freaky, but for some patients it’s all they’ve got.
So can it be done? In 2002 the technique was first demonstrated by Hasan Alam at the University of Michigan Hospital in Ann Arbor and colleagues on pigs. The animals were sedated and a massive haemorrhage induced, to mimic the effect of multiple gunshot wounds. Their blood was drained and replaced by either a cold potassium or saline solution, rapidly cooling the body to around 10 °C. After the injuries were treated, the animals were gradually warmed up as the solution was replaced with blood. Typically, the heart started beating by itself after blood was circulated back, some however needed a jump-start. Following the procedure, there was no visible physiological or brain damage.
“After we did those experiments, the definition of ‘dead’ changed,” says Rhee. “Every day at work I declare people dead. They have no signs of life, no heartbeat, no brain activity. I sign a piece of paper knowing in my heart that they are not actually dead. I could, right then and there, suspend them. But I have to put them in a body bag. It’s frustrating to know there’s a solution.”
Because there are little metabolic reactions in the body at such a low temperature, the patient can be resurrect in a two-hour window, compared to five minutes at normal temperature.
The next step is to do it on humans, and soon enough the doctors at UPMC Presbyterian Hospital will have their shot. The team there will be paged when the ideal patient enters the hospital door – the patient will have suffered a cardiac arrest after a traumatic injury, and will not have responded to attempts to start their heart. Typically, such a patient only has a 7% chance of survival. The technique will be tested on 10 people, and the outcome compared with another 10 who met the criteria but who weren’t treated this way because the team wasn’t on hand. Then after refining, the technique will be tested again on 10 patients that fit the profile. Detailed results will then follow.
The patients involved in the surgery will most likely suffer from near fatal wounds for which there is no alternative treatment. Because the patient will most likely storm in the operating room, there will be little time to notify the family and ask for approval. The trial will go ahead, however, because the US Food and Drug Administration considers it to be exempt from informed consent.
All this talk of suspended animation begs another question, and some of you may already be pondering – what about hibernation. Could we use the same technique to freeze our consciousness and travel to far away worlds? As it is now, the saline technique might keep a human body in suspended animation for up to two hours. You’d need years, decades actually for interstellar flight, but that’s not to say that it’s no possible. It may actually be, but we haven’t decoded all the mechanisms required. In fact, part of the solution may be right out our alley – the lemurs. I recommend you read on this piece to find out more.Click here for reuse options!
Copyright 2014 ZME Science
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