Levels of hypoxia during the trekking to Pyramid Laboratory (5050mt Nepal)

The reduction of oxygen saturation at high altitude is usually measured at rest. In our knowledge no study has ever observed the duration and the level of oxygen desaturation at rest and during exercise, daily and nightly at different high altitudes. AIM: Monitoring of oxygen saturation in a group of sea level residents during the trekking to Pyramid Lab (5050m). METHODS: 8 trekkers (3M, 3F) mean age 35(range 26-59) were studied at sl, 3500m, 4200m, 5050m (1st and 4th day) and during the ascent from 2600m to 3500m, 3800m to 4200m. Oxygen saturation (SpO2%)was measured at rest in the morning (3’ observation) and monitored 24 hrs by a pulsoximeter (Pulsoxi3I,Minolta). RESULTS: At sea level SpO2% range 98-99. For other altitudes see Table 1. Duration of desaturations: 3500m: 15hrs<90%, 7 hrs<85%; 4200m 11hrs<90%, 13hrs<85%; 5050m 5hrs <90%, 18hrs<85%. CONCLUSION: At altitude >3500m the mean SpO2 during 24hrs is significantly lower as compared to rest value. Continuous SpO2 monitoring at high altitude allows to better understand the severity and duration of oxygen desaturations to which trekkers and climbers are exposed during high altitude activities. Table 1 : SpO2 mean value at rest 3 min (first line) and during 24hrs (second line). 2600m 3500m 4200m 5050m 1 5050m 4 94 90,9 87,2 83,5 85,1 na 83,3* 80,7* 73,8* 72,7* * = p<0.05