Cho Oyu 2005 - blood samples at very high altitude. In the autumn of 2005, the Anglo-Irish Xtreme Everest Expedition to Cho Oyu (8,188m) undertook a number of ambitious scientific projects at high altitude. The seven-man team, which comprised Roger McMorrow (leader) with Vijay Ahuja, Nigel Hart, Mick O’Dwyer, Paul Richards, George Rodway, Piotr Szawarski and I, completed work on the effects of supplemental oxygen on well-acclimatised mountaineers during sleep, exercise, and treatment inside a portable hyperbaric chamber (a.k.a. Gamow Bag).

In addition, six members reached the summit over two consecutive days, accompanied on each occasion by Nanmygal Sherpa, who not only reached the summit twice within 24 hours but was also able to descend to Camp 1 at 6100m in just 4 hours, in order to deliver a sample of blood after the second summit bid. The sample had been obtained from inside a small, lightweight shelter erected on the summit, with Mt Everest clearly visible in the distance. This was the first attempt ever to obtain information about the concentrations of oxygen and carbon dioxide at such altitudes and provided the foundations for the Xtreme Expedition to Everest in 2007.

Dr. Jeremy Windsor, UK