Association Between Decreased Pulse Oximetry and Acute Mountain Sickness Upon Rapid Ascent to 4,086 m Among Young Chinese Men.

UNLABELLED: Tang, Xu-gang, Xiu-chuan Li, Bao-mei Song, Shuang Li, Qiang Wang, and Yong-jian Yang. Association between decreased pulse oximetry and acute mountain sickness upon rapid ascent to 4,086 m among young Chinese men. High Alt Med Biol. 27:49-46, 2026.

BACKGROUND

Research on predicting acute mountain sickness (AMS) based on the decreased pulse oximeter saturation (SpO2) during rapid train travel to high altitudes is limited and inconsistent. We aimed to assess whether lower SpO2 levels are associated with AMS in a young Chinese male population following a rapid ascent to high altitude by train.

METHODS

The study involved 375 young Chinese men with a median age of 21. The participants spent 43 hours ascending from an altitude of 400 m to 4,086 m, including 41 hours by train and 2 hours by car. They were divided into AMS+ and AMS- groups based on the Lake Louise AMS score (LLS) after being exposed to 4,086 m for 24 hours. Participants' SpO2 and heart rate (HR) were measured. AMS was assessed using the LLS. Data were analyzed using Spearman's correlation, logistic regression, and receiver operating characteristic (ROC) analysis.

RESULTS

At 4,086 m, the overall AMS prevalence was 31%. The HR was significantly higher in the AMS+ group compared to the AMS- group. Conversely, SpO2 was lower in the AMS+ group. Correlation analysis showed that LLS was positively correlated with HR and negatively correlated with SpO2. Adjusted logistic regression identified lower SpO2 (OR = 0.909, 95% CI: 0.867-0.953, p < 0.001) and HR (OR = 1.031, 95% CI: 1.010-1.052, p < 0.01) as independent risk factors for AMS. ROC analysis indicated that lower SpO2 is a significant marker for diagnosing moderate to severe AMS. The optimal cut-off value for SpO2 was 81.5%, with a sensitivity of 66.7%, a specificity of 75.7%, and an AUC of 0.724, with lower and upper confidence limits of 0.555 and 0.893, respectively.

CONCLUSION

This study suggests that lower SpO2 levels are associated with AMS in young Chinese men who rapidly ascend to 4,086 m, primarily by train.