Cardiorespiratory Responses During High Altitude Ascent to 5160m in Nepal

Relationships to Self-reported AMS

Abstract

Individuals ascending to high altitude risk developing acute mountain sickness (AMS). The Lake Louise AMS scoring system is a self-reporting tool without quantitative physiological metrics. The purpose of this study was to assess cardiorespiratory acclimatization and AMS severity during an ascent to high altitude. A group of 20 participants trekked to 5160m over nine days in the Nepal Himalaya.

Cardiorespiratory variables were measured every morning following one night at each altitude, including oxygen saturation (SpO2; %), heart rate (HR; min-1), pressure of end-tidal (PET)CO2 (Torr) and respiratory rate (RR; min-1). These measures (delta from 1400m) were correlated with AMS scores during ascent at six altitudes (n=120). Correlations with AMS were as follows: SpO2, significant, moderate negative correlation (ρ=-0.35, PETCO2, no significant correlation (ρ=-0.16, P=0.08); RR, significant, weak negative correlation (ρ=0.24, P=0.008). However, an index combining these four variables ((HR/SpO2)*(RR/PETCO2)) vs. AMS revealed a significant, moderate positive correlation (ρ=0.48, P

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