By Rachael Buchanan
BBC News, Medical Producer
Everest's summit poses a daunting challenge
If you want to research intensive care medicine the top of Mount Everest may seem an odd destination, but for a group of doctors from University College London it represents the ideal laboratory.
These mountaineering medics are interested in the effects of oxygen deprivation on the body - a critical problem for ICU patients - so what better location than the highest point on Earth, where there is just one-third the amount of oxygen that exists at sea level.
The team set off for the world's most famous mountain on Saturday 17 March.
They will spend April performing a variety of experiments on themselves and over 200 volunteers at base camp (5,300 metres).
A smaller team of scientists will climb to the summit in May, where they will take blood samples and repeat some of the tests.
The volunteers have already undergone the same battery of tests in a hospital lab in London in order to establish a personal base line for their oxygen consumption efficiency at sea-level.
Performing 32 different tests on 224 individuals and comparing their sea level to altitude results will help the team build up a picture of why some people cope better with low oxygen levels, and what physiological changes occur in such conditions.
Dr Grocott practised on Mount Blanc
Expedition leader Dr Mike Grocott told the BBC that having such a wealth of data about the body's reaction to oxygen starvation, without the confounding factors of additional injuries, would be invaluable in devising better intensive care treatments.
"One of the problems is that we meet patients when they are already ill, so we don't know much about them before they got to that state, we don't have anything for comparison.
"In this experiment we can do genetic and blood tests and know that the changes we see are due to a shortage of oxygen".
The tests range from measuring subjects' blood flow speed and monitoring the impact of altitude on their mental functions, to putting them through their paces on an exercise bike - an interesting spectacle, half way up a mountain.
But the expedition isn't just a medical marathon.
The logistics of transporting 25 tonnes of freight to seven separate laboratories in Kathmandu and up the slopes of Everest is mind boggling.
Since December, the equipment team have spent days packing 120,000 items into 900 containers.
Preparations have been thorough
Speaking from Kathmandu, the man in charge of this huge task - Mac Mackenney - admitted to the BBC that it has "been busy to say the least!"
He said that "the complicated part has been to ensure that everything ends up in the right place because if we accidentally send something to Base Camp that should be in Kathmandu it would take two weeks to get it back to the right place".
All that equipment has already started its journey to Nepal now, so the team can only hope that their complicated colour coding scheme will work and every piece makes it to the right destination.
Then the science team can get on with their task of making medical history in the highest lab in the world.
The BBC's Horizon team will be following the Caudwell Xtreme Everest team throughout the expedition. You can follow the expedition progress through the Horizon website at bbc.co.uk/horizon.