A new study performed atop Mount Everest shows that humans can survive with far lower blood oxygen levels than expected. These findings, hope the doctors who made them, may have important implications for treating critical care patients.

Setting out on an extreme scientific mission, Mike Grocott, a UCL Senior Lecturer in Critical Care Medicine, and his colleagues scaled the Himalayan summit to examine how altitude affects the body. Metres from the apex, at temperatures around -25°C, the climbing doctors unzipped their down suits are collected blood from the femoral artery in the groin. Back at base camp, they found that the average blood oxygen level at 8,400 metres was 3.28 kilopascals (kPa), and the lowest value was 2.55 kPa. These findings are reported in The New England Journal of Medicine.

“This is far below what was previously thought possible,” Grocott told ”https://www.telegraph.co.uk/health/healthnews/4141689/Doctors-near-top-of-Everest-record-lowest-ever-blood-oxygen-levels.html">The Telegraph. “Previous speculation had been that humans could not function if the levels dropped below 3.9 kPa.”

Currently, doctors will adopt aggressive treatments — such as using a ventilator — to increase a patient’s blood-oxygen level if it falls below 8kPa.

“All these interventions carry a risk of harm and you have to weigh up the benefits versus potential damage to organs like the lungs,” Grocott told the BBC. “Maybe we could be less aggressive in treating some of these patients.”

Anaesthetist Peter Nightingale of the Royal College of Anaesthetists told the BBC that while “researchers may well be right that patients can run on lower oxygen levels”, “we need more research.”

Perhaps in hypobaric chambers, where controls can be designed and test subjects won’t be limited to healthy mountaineering doctors?

Image: NASA