One night's oxygen readings from a wrist-worn pulse oximeter flagged which trekkers on the way to Everest Base Camp would develop acute mountain sickness days later. The study of about 140 trekkers was published in Frontiers in Physiology on 30 September 2026.
A night of oxygen readings from a wrist-worn pulse oximeter gave researchers an early warning of acute mountain sickness (AMS). It flagged which trekkers on the way to Everest Base Camp would develop it a few days later. The study, by a team including the Birmingham Medical Research Expeditionary Society, was published in Frontiers in Physiology on 30 September 2026.
How the study worked
The researchers recruited trekkers in Namche Bazaar (3,440 m11,286 ft) from people already planning to walk to base camp below Everest. Each slept with an oximeter on the wrist and a sensor on a finger, once in Namche and again at the Dingboche level (4,371 to 4,730 m15,518 ft). From each night's oxygen saturation and heart rate, the team worked out 125 measurements. A doctor then checked every trekker for AMS at Lobuche, at about 4,940 m16,207 ft.
Of the 139 trekkers with a usable night in Namche, 30 had AMS at Lobuche. Of the 144 measured at the Dingboche level, 29 did.
What the readings showed
A machine-learning model fed only the oximeter data scored 0.74 on the standard test of a prediction, where 0.5 is a coin toss and 1.0 is perfect. That held at both altitudes. At the Dingboche level, adding basic information about each trekker and their ascent lifted the score to 0.84. The model then picked out about three in four of the trekkers who went on to get AMS.
The signals that mattered most were how long oxygen stayed low through the night, the pattern of the dips, and the variation in heart rate.
What it is meant for
The authors describe it as a screening tool, a way to flag who needs closer watching, a slower pace or preventive treatment, before any symptoms appear. It does not diagnose AMS, and they ask for testing in larger and more varied groups, partly because pulse oximeters read less reliably on darker skin.
For anyone heading high, the practical side is unchanged: a steady ascent and knowing the early signs. The FAQ on how to train to prevent altitude sickness covers what can be done before the trip.