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Xtreme Everest: Cho Oyu

5 January 2006

A team of intrepid UCL scientists are preparing to climb to the summit of Mount Everest in 2007.

As part of the preparations, the team headed for Cho Oyu, the world's sixth highest peak located a short distance to the west of Everest itself.

The team - all of whom work with anaesthesia, intensive care or remote medicine - hope to draw parallels between the human body pushed to its limits during critical illness and changes that occur in extreme environments. Low levels of oxygen in the blood of high altitude climbers is similar to levels in critically ill patients on breathing machines with severe heart and lung conditions, 'blue babies' and cystic fibrosis sufferers.

In the first experiment of its kind, six clinicians will measure the amount of oxygen in their own blood at the summit. In addition, running tests will monitor how well their brains, lungs and metabolism are working.

High altitude laboratories, set up along the route, will enable collaborating teams of scientists to explore many aspects of extreme altitude physiology including illnesses such as fluid on the brain and lungs and acute mountain sickness. A separate project will track and compare the genetic profiles of high altitude natives with those of lowlanders, to identify genes that aid survival in extreme altitudes.

The Cho Oyu trip allowed the team to test essential equipment for the main event. Xtreme Everest expedition leader Dr Mike Grocott (UCL Centre for Aviation, Space and Extreme Environment Medicine) said: "The temperatures on Cho Oyu could change from minus 15°C to over 30°C in little over an hour. The laptop computers we need can operate at those temperatures, but don't appreciate such rapid swings."

One of the pieces of equipment tested was Cho Oyu expedition leader Dr Roger McMorrow's design for a closed circuit re-breather. The highly efficient system filters expelled air through soda lime, allowing it to be mixed with pure oxygen and inhaled again. The system is similar to re-breathers used by divers, but with much longer breathing duration.

The new design has implications not just for high altitude climbers, but also for patients reliant on breathing apparatus. Dr McMorrow added: "This system could make a real difference to patients on a ward where the current open circuit re-breather can only deliver 40-50 per cent oxygen, this system can deliver 100 per cent and free the patient from reliance on pipeline oxygen."

A nasal demand circuit was also tested, which could have applications for oxygen-reliant patients at home. It reduces the amount of oxygen consumed, therefore allowing for smaller, portable canisters. Dr Grocott said: "With this system, oxygen is only delivered when the user breathes in, making it highly efficient compared to oxygen masks that constantly deliver oxygen. The system weighs just one kilogram, so could help patients with chronic lung disease and cystic fibrosis undertake activities that are currently not possible."