A team of British doctors conducting experiments in the "Death Zone" of Mount Everest has recorded the lowest levels of blood oxygen in humans, far below those of critically ill patients.

The findings published on Wednesday could one day lead to better care for patients with heart and lung ailments in intensive care units, premature babies and others suffering from similar low-oxygen levels, known as hypoxia.

"We want to understand why humans respond differently to low oxygen levels," Mike Grocott, a researcher at University College London, who led the study, said in a telephone interview.

"The problem with studying critically ill patients is there are so many other things going on it makes it difficult to single out the effects of any one variable."

The study took place in the so-called "Death Zone" on Everest -- the area above 8,000 metres where thin air limits the amount of oxygen getting into the lungs and can lead to organ failure and coma even for the fittest individuals.

The team of eight doctors reached the 8,850-metre summit via the South Col route but carried out their experiment about 400 metres lower because of severe weather at the top.

After finding an area that provided some shelter, four of the team members removed their gloves, unzipped their down suits and had blood drawn from the femoral artery in the groin.

"The disadvantage is you have to uncover a little bit more of yourself than you would like at those temperatures," Grocott said. The outside temperature at the time was about minus 25 C.

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