Now, test to predict altitude sickness
London: Scientists have developed the first test to predict who will develop altitude sickness.
The test could revolutionise 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.
Researchers from Italy and France looked at how the heart responds to hypoxia - low oxygen levels.
They studied cardiovascular function, using non-invasive, ultrasound-based techniques, in 34 healthy volunteers once at sea level and again after going by cable car up Aiguille de Midi, a mountain in the French Alps, to a height of 12,600 ft.
Around a third of them had experienced severe altitude sickness previously, 'BBC News' reported.
Participants had oxygen saturation levels monitored and had an ultrasound check of their 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.
They had lower oxygen saturation levels and the ultrasound showed poorer function in the systolic (pumping) ability in the right ventricle.
The changes were not seen in people who did not display altitude sickness symptoms.
"If these results are confirmed by larger studies, it will be possible to identify vulnerable individuals and suggest particular behaviours and drugs," said Dr Rosa Maria Bruno, who led the study.
"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 acclimatisation.
"At the moment we don't know exactly why some people can adapt successfully to high altitude and other people cannot, or how to identify susceptible individuals in whom preventative strategies may be applied.
"This can be an important problem since an increasing number of people of all ages go to high altitude, mainly for recreational purposes but also for working without being conscious of the potential risks," she said.
The test can now only be done once people have spent at least four hours at high altitude but the team hopes it can be developed so it can work sooner.
The details of the new test were presented to the EuroEcho-Imaging conference in Istanbul during 11-14 December.