Mountaineers measure lowest human blood oxygen levels on record

Jan 07, 2009

The lowest ever levels of oxygen in humans have been reported in climbers on an expedition led by UCL (University College London) doctors. The world-first measurements of blood oxygen levels in climbers near the top of Mount Everest, 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.

The Caudwell Xtreme Everest team of climbing doctors made the measurements by taking blood from leg arteries close to the summit of Mount Everest at 8,400 metres above sea-level. The team climbed with oxygen tanks, then removed their masks 20 minutes prior to testing to equilibrate their lungs with the low-oxygen atmosphere. The team were unable to make the measurement on the summit of Everest as conditions were too severe, with temperatures at minus 25 degrees centrigrade and winds above 20 knots. Having descended a short distance 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 science laboratory set up at the team's camp at 6,400 metres on Everest.

The purpose of the study was to establish what has long been suspected - that high-altitude climbers have incredibly low levels of oxygen in their blood, which at sea-level would only be seen in patients close to death. The expedition found the average arterial oxygen level to be 3.28 kilopascals or kPa (with the lowest value 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 calculations of the expected level of oxygen in the blood, the authors also speculate that accumulation of fluid in the lungs as a result of the high altitude might have contributed to the low oxygen levels.

Caudwell Xtreme Everest expedition leader Dr Mike Grocott, a 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 extraordinary low levels of oxygen found in high-altitude climbers may cause doctors looking after critically ill patients to revaluate treatment goals in some patients who have been ill for some time and might have adapted to low levels of oxygen in the blood. However, our findings will need further careful evaluation before they can be translated into clinical practice. We hope that ongoing research will eventually lead to better treatments for patients with acute respiratory distress syndrome (ARDS), cystic fibrosis, emphysema, septic shock, 'blue baby' syndrome and other critical illnesses."

Source: University College London

Explore further: US scientists make embryonic stem cells from adult skin

add to favorites email to friend print save as pdf

Related Stories

Patients with mild to moderate OSA may benefit from exercise

May 07, 2009

Practicing certain tongue and pharyngeal exercises may reduce symptoms of mild to moderate obstructive sleep apnea (OSA), according to new research being published in the second issue for May of the American Journal of Re ...

Recommended for you

Leeches help save woman's ear after pit bull mauling

Apr 18, 2014

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

New pain relief targets discovered

Apr 17, 2014

Scientists have identified new pain relief targets that could be used to provide relief from chemotherapy-induced pain. BBSRC-funded researchers at King's College London made the discovery when researching ...

User comments : 0

More news stories

Cancer stem cells linked to drug resistance

Most drugs used to treat lung, breast and pancreatic cancers also promote drug-resistance and ultimately spur tumor growth. Researchers at the University of California, San Diego School of Medicine have discovered ...

Finnish inventor rethinks design of the axe

(Phys.org) —Finnish inventor Heikki Kärnä is the man behind the Vipukirves Leveraxe, which is a precision tool for splitting firewood. He designed the tool to make the job easier and more efficient, with ...

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.