British researchers have found that the established medical rules about the amount of oxygen needed by a body under stress might be wrong. The world-first measurements of blood oxygen levels in climbers near the top of Mount Everest (29,029 ft), published in this week's New England Journal of Medicine (NEJM), could eventually help critical care doctors to re-evaluate treatment strategies in some long-term patients with similarly low levels of blood oxygen.

Dr. Mike Grocott, a lecturer in critical care medicine at University College London, and his colleagues descended 1200 ft from the summit, took off their gloves, unzipped their down-filled suits and drew blood from four team members. The blood was analyzed within two hours at a laboratory set up at the team's camp at about 21,120 ft above sea level.

Knowing that critically ill patients show a level of about eight kilopascals, and the normal level is 12 to 14 kilopascals, researchers now found the lowest-ever recorded level of 2.55 kilopascals.

An analysis showed what doctors had long suspected: that high-altitude climbers have incredibly low levels of oxygen in their blood, normally seen only in patients close to death. Grocott and colleagues believe a build-up of fluid in the lungs due to the high altitude might have contributed to the low oxygen levels.

The finding may shed light on arterial hypoxia in critically ill patients, and may open the door to treatment without the use of supplemental oxygen or ventilation which cause damage to the lungs. However more work is needed before the findings can actually be translated into clinical practice.