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sts.components.contact.mr.placeholder Sebastian Webel
Mr. Sebastian Webel

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Pictures of the Future
The Magazine for Research and Innovation
 

Health and Human Life

Cutting-Edge Research at the Top of the World

Researchers are developing insights into altitude sickness using Mt. Everest as a living laboratory.

During the summer of 2013, Mount Everest’s base camp was transformed into a research lab. Together with 200 volunteers, a team of scientists used the camp to study the effects of altitude sickness. The results might soon be used to develop new treatments for patients in intensive care.

Nothing but ice and rock as far as the eye can see. A huge glacier soars above the rugged landscape. At night, temperatures drop as low as 30 degrees Celsius below zero. The air is so thin that humans cannot survive for extended periods. It doesn’t sound like an agreeable location to pitch a tent; yet this is the perfect location for research that might one day revolutionize the treatment of patients in intensive care.

Research at 5,300 Meters above Sea Level

In the summer of 2013, a British-American research team set up their tents here at Mount Everest’s south base camp, 5,300 meters above sea level. They came 60 years after man’s first ascent to the top of the world’s highest mountain, to learn more about how oxygen deficiency, also known as hypoxia, affects humans. This knowledge could help to increase the survival rate of patients in intensive care.

The project’s name, Xtreme Everest 2, says it all. Eleven doctors and researchers from University College London, the University of Southampton, and Duke University (North Carolina) spent 83 days at this inhospitable location, 49 of them at the base camp. The scientists were accompanied by around 200 volunteers willing to make the arduous climb to serve as test subjects. The doctors conducted thousands of tests on themselves and the other participants, taking more than 4,000 blood samples in the process.

Shedding Light on Hypoxia

The scientists’ findings could save the lives of many people suffering from heart or lung disease. In 2011 Germany recorded more than two million cases that required intensive care. In the UK, one fifth of the population will spend time in intensive care at some point during their lives. Two fifths of these patients will die, in many cases as a result of oxygen deficiency, or hypoxia.

“Human beings can adapt to oxygen deficiency, although they do so at different rates,” explains the expedition’s leader, Dr. Daniel Martin, Senior Lecturer in Anaesthesia and Critical Care Medicine at University College London. “For example, if 100 people get pneumonia, 25 of them will shake it off within a week. Half of them will have to be hospitalized and will take about four to six weeks to get better. The remaining 25 patients will be dead within a week, despite intensive care and the administration of oxygen.”

Red Bood Cells at the Top of the World

At the Mount Everest base camp, the atmospheric pressure is only half of what it is at sea level. This means that only half as much oxygen enters the lungs during inhalation. At sea level, oxygen saturation (i.e. the proportion of red blood cells carrying oxygen) is 100 percent, but at the base camp it drops to only 70 percent. This is equivalent to that of a person suffering from hypoxia. The human body responds to decreasing atmospheric pressure by producing more red blood cells so that a greater amount of oxygen can be carried in the blood. As with Dr. Martin’s hypothetical pneumonia patients, 25 percent of those who travel to this altitude suffer no problems as a result of the low atmospheric pressure. Around half contract altitude sickness and require additional oxygen. The remaining 25 percent experience extreme nausea, headaches or dizziness.

Why some people can adapt to high altitudes better than others is a medical mystery. But this knowledge could play a key role in improving the treatment patients receive while in intensive care. Patients in an intensive care unit suffering from hypoxia are always given additional oxygen, usually by means of artificial respiration. However, increased oxygen inhalation is not without risk. The treatment’s high respiration pressure can damage blood vessels in the retina, and breathing in too much oxygen can damage the lungs if done over an extended period. “Instead of pumping patients full of oxygen, blood, and medication to enhance heart rate, we might find a way to slow down physiological processes so that the body has more rest and time to heal itself,” suggests Dr. Martin.

In their search for answers, scientists are faced with the dilemma that severely ill patients in intensive care can hardly be subjected to extensive medical tests. Simulations in altitude chambers are also inadequate for such large-scale research. That’s why the scientists working on the Xtreme Everest project subjected 200 healthy people to oxygen deficiency, simulating the hypoxia suffered by hospital patients.

At an altitude of 8,848 meters, there is only one third as much oxygen as at sea level.

The project team had already gone to Everest in 2007. Together with several other participants, Dr. Martin climbed all the way to the summit where, at an altitude of 8,848 meters, there is only one third as much oxygen as at sea level. The researchers took blood samples from one another only a few hundred meters from the peak. The level of oxygen in Dr. Martin’s blood was the lowest that has ever been measured in a healthy person.

The scientists on the 2007 expedition were also accompanied by 200 healthy volunteers. At the base camp, the researchers used blood gas analysis devices from Siemens to examine the subjects. One of the first findings was that the human body seems to exhale more nitric oxide when there is little oxygen in the air. Nitric oxide gas expands blood vessels, causing blood to flow more strongly and thus improving the supply of oxygen to the body. However, the first expedition left many questions unanswered — questions Xtreme Everest 2 set out to resolve. As a result, in 2013 some 200 participants once again climbed to the Mount Everest base camp and were examined at temporary labs that were set up at various altitudes. The participants included children aged eight to 17, who trekked to a lab located 3,500 meters above sea level, as well as identical twins and individuals who had taken part in the 2007 expedition.  

Sherpas' Secret Weapon: Nitric Oxide

A group of native Sherpas also took part. Sherpas’ tolerance for hard labor and their ability to carry heavy loads at high altitudes made them an important part of the experiment. “Scientists used to think that Sherpas can transport more oxygen in their blood than lowlanders,” says Dr. Martin. “But that’s not the case. Their hearts function the same way as ours, and their oxygen supply is the same as well. The answer is that Sherpas can process oxygen better than we can.” In fact, the researchers found out that the Sherpas’ microcirculation is much better than that of other people and their blood contains far more nitric oxide. “Whenever there is too little oxygen, Sherpas seem to respond by producing more nitric oxide. In samples taken at 3,500 meters, the breath of one of the ‘normal’ participants contained 16.4 ppb of nitric oxide, while that of a Sherpa contained 77.8 ppb,” added Martin. Nitric oxide increases blood flow and changes the way in which mitochondria process oxygen. Put simply, it enables them to make better use of the small amount of oxygen they get.

Scientists hypothesized that the more nitric oxide a person’s body contains, the better he or she can cope with high altitudes

The scientists hypothesized that the more nitric oxide a person’s body contains, the better he or she can cope with high altitudes. As a result, patients in intensive care could conceivably receive medication that changes the nitric oxide level of their blood in the hope of increasing their chances of survival.

As was the case in 2007, expedition participants were examined using blood gas analysis devices from Siemens, which are robust and weigh approximately 11 kg. The expedition was accompanied by Siemens employee Steve Carey, team leader for blood gas systems maintenance at Siemens Healthcare in the UK. When Carey learned of the project he immediately took advantage of this opportunity to test “his” measuring devices on the world’s highest mountain. In addition to making sure that all of the instruments worked smoothly during the expedition, Carey served as a test subject.

Early Morning Exercises

The conditions on Mount Everest were challenging not only for participants but also for the measuring devices. Prior to the expedition, Siemens simulated the mountain’s temperature and atmospheric pressure in an altitude chamber so that various systems could be calibrated to deliver accurate results. The instruments faithfully performed their tasks during the expedition, even though they occasionally needed a little assistance. “We sometimes had to put an electric blanket underneath the devices so that the liquids they contained wouldn't freeze,” says Carey.

More than 60 tests were conducted on the volunteers. “We got up at 6 a.m., conducted various blood tests, measured participants’ respiratory rate, and did a prescribed series of early morning exercises,” says Carey. One impression remains particularly vivid for him. “Many of the Sherpas had never before seen an exercise bike,” he says. “They had to do the same exercises as the rest of us, but some had to have their feet taped to the pedals because they kept falling off!”

The ongoing research project is being funded by donations. More than ₤850,000 has been collected to date, and an additional ₤250,000 is needed so that the data can be fully analyzed and all of the information and findings compiled in a comprehensive database. That’s why it is still too early to say anything definite about the final outcome. However, the scientists have already made some surprising discoveries. Women seem to be able to handle high altitudes better than men, while older men are less affected by altitude sickness than younger ones. But Dr. Martin has a simple explanation for these findings: “Young men tend to want to climb the mountain too fast, and that makes them more likely to suffer from altitude sickness,” he says. On mountains as elsewhere, slow and steady wins the race.

 

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Nicole Elflein