British Services Dhaulagiri Medical Research Expedition

THE APPROACH

This high-altitude medical research was wide ranging investigating:

• The effects of acclimation (simulated normobaric hypoxia, apnoea training) on performance
• Biomechanical changes in walking and balance
• Appetite responses; cardiac rhythm
• Central blood pressure; heart rate variability
• Hormonal marks of altitude illness
• The effect of iron infusion on the ability to cope with high altitude exposure

Research was carried out with the main military team aiming to climb Dhaulagiri (8,167m), the 7th highest peak in the World, in a testing and challenging Alpine style. In addition, eight medical research trek teams completing the Dhaulagiri circuit took part. Following baseline measurements in the UK, each trekking team who departed Kathmandu several days apart visited three research camps at increasing altitudes, taking part in the most comprehensive medical research expedition to high-altitude of its kind

This project presented a substantial logistical challenge with half a ton of research and medical equipment being shipped to Nepal from Leeds to establish the research camps. Honda provided us with generators to power our equipment in such an austere environment. Use of dewars filled with liquid nitrogen allowed us to rapidly freeze and store biological samples and contributed to a ‘cold chain’ stretching all the way from Nepal to our laboratory facilities in Leeds.

THE IMPACT

We were able to establish that high-altitude places significant stress on the heart with exposures above 4000m associated with significant brady- and tachyarrhythmias, supporting a potential proarrhythmic risk. However, no link was detected between high-altitude and sustained ventricular arrhythmias linked to an increased risk of sudden cardiac death. In addition, we showed increases in certain central blood pressure variables, which were related to sympathetic activation associated with high-altitude exposure, rather than any genuine change in arterial stiffness. This has impacted our screening procedures when recruiting participants, whereby we now assess their heart function before we exposure them to altitudes above 4000m. 

High altitude was shown to impair postural control, which is important in terms of a heighten risk of falling on rough terrain whilst trekking or climbing at high-altitude. Our research was the first to demonstrate that changes in plasma acylated and total ghrelin concentrations may contribute to the suppression of appetite. An understanding of the mechanisms of appetite suppression, will help in the development of specific nutritional interventions to maintain appetite and energy balance during expeditions to high-altitude. 

The above provides a glimpse of some of the novel findings from this research. For additional information, please see our publications from this project, which are highlight below.