Climbers near the top of Mount Everest showed the lowest ever blood level of oxygen recorded in humans — a finding that could someday lead to better care for patients in intensive care who suffer from similar low oxygen levels, the researchers say.
In Thursday's New England Journal of Medicine, Dr. Mike Grocott, a lecturer in critical care medicine at University College London, and his colleagues said they made the measurements close to the summit of Mount Everest, at 8,400 metres above sea level.
Conditions were too severe at the summit itself, with temperatures of –25 C and high winds.
"The disadvantage is you have to uncover a little bit more of yourself than you would like at those temperatures," Grocott told Reuters.
To collect samples, the doctors descended 400 metres 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 6,400 metres above sea level.
As suspected, the climbers had extremely low levels of oxygen in their blood.
Researcher found the lowest-ever recorded level was 2.55 kilopascals — a unit of pressure.
In comparison, critically ill patients show a level of about eight kilopascals, and the normal level is 12 to 14 kilopascals.
Critical illness applications?
Based on calculations of the expected oxygen levels in the blood, the study's authors speculated that a buildup of fluid in the lungs as a result of the high altitude might have contributed to the low oxygen levels.
"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," Groscott said in a release.
"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."
More work is needed before the findings can be translated into clinical practice, but the results suggest that some critically ill patients may be able to adapt to low levels of oxygen in the blood, the researchers said.