The use of pulse oximetry (SpO2) to identify subjects susceptible to AMS is the subject of debate. To obtain more reliable data, we monitored SpO2 for 24 hours at altitude to investigate the ability to predict impending AMS. Methods The study was conducted during the climb from Alagna (1154m) to Capanna Regina Margherita (4559m) with an overnight stay in Capanna Gnifetti (3647m). Sixty-two subjects (11F) were recruited. Each subject was fitted with a 24-hr recording finger pulse oximeter. The subjects rode a cable car to 3275m and climbed to 3647m, where they spent the night. Results In the morning, 24 (4F) had a Lake Louise Questionnaire score (LLS) ≥3 (AMS+), and 15 (4F) exhibited moderate to severe disease (LLS ≥5 = AMS++). At Alagna, SpO2 did not differ between the AMS- and AMS+. At higher stations, all AMS+ exhibited a significantly lower SpO2 than did the AMS-: at 3275m, 85.4% vs 87.7%; resting at 3647m, 84.5% vs 86.4%. The ROC curve analysis resulted in a rather poor discrimination between the AMS– and all of the AMS+. With the cut-off LLS ≥5, the sensitivity was 86.67%, the specificity was 82.5%, the AUC was 0.88 (p <0.0001) for SpO2≤84% at 3647m. Conclusions We conclude that AMS+ exhibit a more severe and prolonged oxygen desaturation than do AMS- starting from the beginning of altitude exposure, but the predictive power of SpO2 is accurate only for AMS++.
Long-term monitoring of oxygen saturation at altitude can be useful in predicting the subsequent development of moderate to severe Acute Mountain Sickness
COGO, Annaluisa
2014
Abstract
The use of pulse oximetry (SpO2) to identify subjects susceptible to AMS is the subject of debate. To obtain more reliable data, we monitored SpO2 for 24 hours at altitude to investigate the ability to predict impending AMS. Methods The study was conducted during the climb from Alagna (1154m) to Capanna Regina Margherita (4559m) with an overnight stay in Capanna Gnifetti (3647m). Sixty-two subjects (11F) were recruited. Each subject was fitted with a 24-hr recording finger pulse oximeter. The subjects rode a cable car to 3275m and climbed to 3647m, where they spent the night. Results In the morning, 24 (4F) had a Lake Louise Questionnaire score (LLS) ≥3 (AMS+), and 15 (4F) exhibited moderate to severe disease (LLS ≥5 = AMS++). At Alagna, SpO2 did not differ between the AMS- and AMS+. At higher stations, all AMS+ exhibited a significantly lower SpO2 than did the AMS-: at 3275m, 85.4% vs 87.7%; resting at 3647m, 84.5% vs 86.4%. The ROC curve analysis resulted in a rather poor discrimination between the AMS– and all of the AMS+. With the cut-off LLS ≥5, the sensitivity was 86.67%, the specificity was 82.5%, the AUC was 0.88 (p <0.0001) for SpO2≤84% at 3647m. Conclusions We conclude that AMS+ exhibit a more severe and prolonged oxygen desaturation than do AMS- starting from the beginning of altitude exposure, but the predictive power of SpO2 is accurate only for AMS++.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
