Usability of pulse oximetry during severe physical exercise at high altitude

Abstract

Introduction: Pulse oximetry is widely used to measure blood oxygens saturation (SpO 2 ) and acclimatization status in order to assess acclimatisation status at altitude and there is evidence suggesting that SpO 2 during exercise is more relevant than measurements at rest. But movement, especially of the hands, can lead to incorrect measurements and artefacts, when the oxy-meter is attached to a finger, which in turn might limit the use of pulse oximetry. ›› Key question: We aimed to evaluate the rate of incorrect measurements during extreme exercise (ice climbing) in order to assess the applicability of pulse oximetry during activity. ›› Material and Methods: We analyzed an extreme ice-climb to the summit of Les Courtes (3856 m; NE-gully: 800 m; 50°) in a male 32-years old mountain guide. The pulse oximeter (PalmSat 2500®; Nonin) logs the measured values for SpO 2 and pulse every 4 seconds and detects incorrect data, allowing calculate the proportion of incorrect measurements. ›› Results: During the whole tour 24.8% (1333/5368) of incorrect measurements were detected, 34.5% (778/2252) during the ice climb. The highest proportion of incorrect measurements occurred during the preparation for the ice-climb, 55.6% (81/145). For a normal alpine activity (total tour without ice-climb and the associated preparation time) the rate of incorrect measurements was 16.8% (510/3028). ›› Discussion: Even during exercise in extreme conditions like ice-climbing, pulse oximetry provides approx. 33% valid SpO 2 values, allowing a meaningful monitoring of blood oxygenation.