New test may predict altitude sickness for mountain climbers
Researchers say that they have developed a test that may predict altitude sickness. (Patrick Poendl/Shutterstock.com)
Published Friday, December 13, 2013 8:44AM EST
As any mountain climber knows, reaching high altitudes is not without its thrills and risks. But now scientists say that they can help a problem that until now was difficult to predict -- mountain sickness.
A team of researchers in Italy and France announced Thursday that they have developed a test that could revolutionize trekking and climbing by predicting who will develop the potentially deadly condition so they can avoid high altitudes, ascend more gradually, or take preventative medication, which causes side effects.
The team presented their research at EuroEcho-Imaging 2013 in Istanbul.
It's hard to determine who will be affected by altitude sickness, since there are no specific factors that correlate with those susceptible to the illness.
Symptoms of mountain sickness include headache, nausea, dizziness, fatigue, loss of appetite, and insomnia, which occur in about 30 per cent of people who develop the illness. Around 1 to 2 per cent of people develop potentially life-threatening conditions, such as fluid in their lungs or brain.
"It is well known that when ascending to high altitude the quantity of oxygen (O2) in the air becomes lower and lower," said Dr. Rosa Maria Bruno, first author of the study. "Thus people going to high altitude, above 2,500 meters, develop hypoxia, which is a reduced content of O2 in the blood and tissues."
How people respond to hypoxia, or low oxygen levels, varies, she adds, with some adapting successfully while others experience severe symptoms, known as acute mountain sickness.
In their research, the team looked at how the heart responds to hypoxia by studying cardiovascular function using ultrasound-based techniques in 34 healthy volunteers. Subjects were tested at sea level and again after going by cable car up Aiguille de Midi in the French Alps, to 3,842 metres. Scientists analyzed each subject's oxygen saturation level and heart function, using a portable device, after four hours on the mountain.
After 24 hours at high altitude, 13 out of 34 volunteers developed moderate to severe symptoms. Those same volunteers had lower oxygen saturation levels and their ultrasounds showed poorer heart functioning -- and these changes were visible after only four hours at high altitudes. The changes were not seen in people who didn't experience mountain sickness symptoms.
"Our results suggest that it is possible to identify vulnerable individuals and suggest particular behaviors and drugs only to this subgroup," Bruno says. "Thus we can limit drug use (and side effects) only to those who will really need them, and give them special advice and recommendations such as avoiding high altitudes or spending more time ascending to allow time for acclimatization."