Mountaineers record lowest blood oxygen levels

January 9th, 2009 - 5:13 pm ICT by IANS  

London, Jan 9 (IANS) The lowest oxygen levels ever recorded in humans beings were measured on an Everest expedition, led by University College of London doctors. The findings proved what has long been suspected, that high-altitude climbers have incredibly low levels of blood oxygen, which at sea-level would only be seen in patients close to death.

These measurements in climbers near the Everest top, for the first time in the world, could help doctors re-evaluate treatment strategies in some long-term patients with similarly low levels of blood oxygen.

Caudwell Xtreme Everest (CXE) team of climbing doctors made the measurements by taking blood from leg arteries close to the summit of Everest at 8.4 km above sea level.

The mountaineers climbed with oxygen tanks, then removed their masks 20 minutes prior to testing to equilibrate their lungs with the low-oxygen atmosphere. They were unable to take the measurement on Everest top as conditions were too severe, at 25 degrees Celsius below zero and winds above 20 knots.

Having from the summit, the doctors removed their gloves, unzipped their down suits and drew blood from the femoral artery in the groin.

Blood collected from four team members was then carried back down the mountain to be analysed within two hours at a lab set up at the team’s camp at 6,400 metres.

The expedition found the average arterial oxygen level to be 3.28 kilopascals or kPa (with the lowest being 2.55 kPa); the normal value in humans is 12-14 kPa and patients with a level below 8 kPa are considered critically ill.

Based on such calculations, the authors also speculate that fluid accumulation in the lungs as a result of the high altitude might have contributed to low oxygen levels, said a University College London (UCL) release.

CXE expedition leader Mike Grocott, UCL senior lecturer in critical care medicine, said “by observing healthy individuals at high altitude where oxygen is scarce, we can learn about physiological changes that can improve critical care at the hospital bedside, because low oxygen levels are an almost universal problem in critical care.”

These findings were published in the New England Journal of Medicine (NEJM).

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