July 28th, 2014

High altitude illness

EURAC Institute of Mountain Emergency Medicine

Staying two weeks at almost 4000 m on the peak of Ortles Mountain is not only a stress for the body but also a considerable logistical difficulty in the case of a rescue” says Giacomo Strapazzon, vice head of the EURAC Institute of Mountain Emergency Medicine. It is for this reason that the Ortles project members needed an assistance medical team during the field work. But beyond the safety aspect, the expedition had ideal characteristics to perform an independent study on high altitude illnesses. In contrast to previous work in this field in which participants are monitoring during gradual ascent at high altitude, our participants were transported by helicopter to 4000 m, i.e. without physical effort and within a few minutes, and remained at this altitude for 2 weeks. This allowed complete monitoring of the acute acclimatization process of the body after this rapid ascent to altitude. The medical research included traditional clinical examination as well as ultrasonography and blood analysis before and during the expedition. Ultrasonography of the optic nerve and lungs were tested as a possible tool for early diagnosis of high altitude pulmonary or cerebral edema, two of the most important causes of death among mountaineers.

Some participants experienced common symptoms of high altitude including nausea, headache and respiratory symptoms. The ultrasonography results showed that there was an increase in the optic nerve sheath diameter compared to baseline values (measured at low altitude) and that this increase was measureable within 9 hours after exposure to altitude. The optic nerve sheath diameter is an indicator of the intracranial pressure and thus may be used to monitor common problems that high altitude may inflict on the central nervous system, most importantly high altitude cerebral edema. “The most important aspect of these findings is that the increase was significant before the onset of clinical symptoms,” explains Strapazzon, “and although the optic nerve sheath diameter cannot be used as the only indication, it is a good starting point.”

Similarly, the onset of altitude-related symptoms may partially reflect an imbalance in the regulation of fluids in the lungs and body, which can in some cases lead to pulmonary edema. This was also investigated during the study, again using a combination of ultrasonography, clinical examinations and laboratory results.

To perform a medical study of this sort requires also precise logistical organization. At 4000 m we had to find methods to warm the examination tent without electricity, conserve blood samples in liquid nitrogen and dry ice and protect the ultrasound machine and all materials from low ambient temperatures that reached -20°C at night,” says Hermann Brugger, head of the EURAC Institute of Mountain Emergency Medicine. The researchers also tested the use of some instruments that until now have only been validated at low altitudes, for example the C-PAP device (a device that creates positive pressure during respiration and improves oxygen uptake) and an automatic chest compression device used for mechanical CPR on cardiac arrest patients.

Contacts:

Hermann Brugger, EURAC Institute of Mountain Emergency Medicine hermann.brugger@eurac.edu

Giacomo Strapazzon, EURAC Institute of Mountain Emergency Medicine giacomo.strapazzon@eurac.edu