Prediction of acute mountain sickness and sleep apnea in subjects travelling to and training at altitude

Abstract

Acute mountain sickness (AMS) is a debilitating health problem that affects a number of subjects when ascending to high altitude. Symptoms can include headache, nausea, lethargy, fatigue and subsequent loss of sleep and performance, however if susceptible subjects could be identified early precautionary measures could be put in place to reduce or eliminate AMS. The aim of this study was to determine if physiological variables measured at sea level could predict AMS (as measured by the Lake Louise score) at real altitude. A series of physiological measures were taken at rest at sea level (Dunedin, New Zealand) and again at 5050m (Pyramid Research Laboratory, Nepal). Measures included oxyhaemoglobin saturation, haematocrit, haemoglobin concentration, blood pressure, heart rate, cerebral blood flow and a number of ventilatory measures. We found that sea-level cerebral blood flow (R = 0.47), and haematocrit (R= -0.50) were strongly correlated with AMS, however using multiple linear regression results indicated that sea-level mean blood pressure was the only statistically significant predictor of AMS at altitude (p < 0.01). This analysis indicated that sea-level mean blood pressure accounted for 45% of the prediction of AMS at altitude. In conclusion, while sea-level mean blood pressure is a useful predictor of AMS at altitude, clearly other factors account for the remaining 55% of AMS at altitude, and further research is required to uncover these remaining factors.