EARLY OXYGEN DESATURATION IS RELATED TO AMS DEVELOPMENT DURING ACUTE EXPOSURE TO HIGH ALTITUDE (HA

Early desaturation during acute HA exposure (hypobaric chamber) has been reported to be significantly related to AMS development. We aimed to study the hypoxic profile and the AMS development during the ascent from Alagna (1200m) to Capanna Regina Margherita (4559m) with an overnight stay in Rifugio Gnifetti (3647m). Forty-four (8F) subjects (mean age 37.412.7) were recruited at the cable care station in Alagna, equipped with a 24-h data memory pulse oximeter (Pulsox-3Si,Minolta, Osaka, Japan) and asked to fill the Lake Louise questionnaire. Only data from Alagna to Rifugio Gnifetti and the subsequent night are reported. Fifteen subjects (34%) showed a LL score ≥3 (AMS+). In Alagna, SpO2 data were similar (94.5%1.6 vs 95%1.4 n.s.) but during HA exposure AMS+ group had a significantly lower SpO2: at Punta Indren (3275m) after a 30-45 minutes cable car ascent (84%4.5 vs 86.8%3.7 p <0.049; in Rifugio Gnifetti during 3 hours rest after the arrival (84%2.1 vs 86.11.9 p<0.01) and during the subsequent night (76.7%3.8 vs 79.1%3.4 p 0.049). There was no significant difference during the 2 hours exercise to reach Rifugio Gnifetti (81.3%2.9 vs 82.1%2.5 n.s.). No difference was found in the lower peak SpO2 during the night but the AMS+ group always spent more time with a lower SpO2: percentage of total time spent with SpO2 <85% at rest in Rifugio Gnifetti was 56%20.6 vs 34%18 p 0.017; percentage of total time spent with SpO2