The U.S. military invests heavily in the performance of its soldiers: making them stronger, sturdier and tougher. We continue our series about how the Pentagon is scientifically trying to build a more durable soldier. The World's Jason Margolis reports on experiments aimed at extending the so-called ‘Golden Hour'. The brief window of time needed to evacuate a soldier bleeding to death and bring him to hospital.

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Dr. Irshad Chaudry

Margolis: Dr. Irshad Chaudry is the director of the center for surgical research at the University of Alabama. He's written more than 500 papers on topics about the immune system, cardiovascular function, and trauma. A highly accomplished scientist, the military approached him with a scenario of a heavily bleeding soldier.

Chaudry: "The soldier has lost a lot of volume; unfortunately they are on the forefront. So you cannot resuscitate them, you can't evacuate them for a certain period of time. And what do you do to stabilize them without giving massive fluids? Because there's no facility to give them fluids."

Margolis: Without proper treatment the soldier would likely die within an hour. The military challenged Chaudry: Give us more time. The agency that made such an audacious request is called DARPA. That stands for the Defense Advanced Research Projects Agency.

Chaudry thought about this challenge. In order to cheat death, he looked at the building blocks of life, at women and the menstrual cycle.

Chaudry: "Every month they lose blood, and as a consequence of that, the body is conditioned to tolerate blood loss far, far better than males."

Margolis: What gives women this physiological advantage? The answer is estrogen. The female hormone helps restore blood volume, and keeps blood pressure high. Chaudry took this knowledge into the laboratory.

In a windowless basement room, several large pigs are bleeding almost to death. Over an hour scientists remove 60 per cent of the animals blood to mimic a severe battlefield wound. For humane reasons the pigs are heavily sedated. The animals are hooked up to ventilators and electrocardiogram machines as Scientists as measure heart rate, blood pressure, and breathing.

Medical cardiologist Greg Walcott monitors the animals.

Walcott: "In a controlled situation, most of those animals will die w/in an hour or two.

Margolis: But, if scientists add a steady drip of estrogen...

Walcott: "The animals we've been doing with the estrogen have survived at least three hours and that's when we actually resuscitate the animals by the protocol. They may actually survive longer than that. The goal is first to get to three hours, and if we achieve that, then to move onto six."

Margolis: For a wounded soldier on the battlefront, those extra three hours, could be the difference between living and dying.

Cell biologist Mark RothAcross the country in Seattle, scientists at the Fred Hutchinson Cancer Research Center are trying something entirely different. Cell biologist Mark Roth is researching the role of oxygen and blood loss. First, Roth explains some basic facts about the air we breathe.

Roth: "Everybody knows that we're living in 21 percent oxygen. And as you reduce oxygen tension, around animals, then they pass away, we pass away. You know, anything below 10 percent is very, very dangerous."

Margolis: But, Roth asked: What if we didn't need so much oxygen?

Roth: "The trick is to make sure that oxygen supply always exceed your demand."

Margolis: OK. But how?

Roth conducted some experiments on mice. He found that if you starve mice of oxygen, they die in 10 or 15 minutes. But give them some hydrogen sulfide to breathe, they survive for hours and hours. Essentially, the gas hydrogen sulfide puts the animal into a state of temporary hibernation. This happens because hydrogen sulfide slows down metabolic rates, decreasing the need for fresh oxygen.

This discovery could prove revolutionary for someone with severe trauma, who can't get enough oxygen to the vital organs. Roth compares the way we treat a person with severe blood loss today to a car with a blown out tire.

Roth: "What we're doing now is trying to change the flat tire while we're driving. So that is you're maintaining high metabolic rate, you're trying to go somewhere, and you're trying to change your tire. And that's really not smart. Whereas if you could just simply pull off to the side of the road, decrease your forward progress, briefly, that is enter into a state into a state of hibernation. And park your car briefly, so as to pull the tire off and put a new tire on, then you can resume your trip, and not have difficulties of changing tire at 60 miles an hour."

Margolis: If this trick can work for people, not just lab animals, it could give a wounded soldier some extra time. Perhaps a small pill or vial of hydrogen sulfide or estrogen will someday save soldiers' lives.

And if this can prove effective in helping wounded soldiers, the applications could be groundbreaking for all us. For example, victims of a car crash, or people with a heart attack or stroke, could also buy a little extra time and make it to the hospital...and a second chance at life.

For the World, I'm Jason Margolis.

Web resources
Center for Surgical Research at University of Alabama

Fred Hutchinson Cancer Research Center