Estimation of the degree of acclimatization to high altitude by a rapid and simple physiological examination.

The recent expansion in the geographical areas open to human activity has made it desirable to have an objective method to evaluate the degree of high-altitude acclimatization. In this study, we measured the arterial oxygen saturation value at rest and just after exercise in healthy high-altitude trekkers using a transportable pulse oximeter. During a 100-day stay at high altitude (around 4000 m), the degree of arterial hemoglobin saturation measured at rest was relatively stable. However, shortly after arrival at high altitude, even light exercise induced an acute reduction in the degree of arterial hemoglobin saturation; this reduction was ameliorated as the trekkers became acclimatized to the high altitude. Preliminary short trekking to high altitudes does not appear sufficient to induce this response. It is suggested that this rapid and simple physiological examination, the measurement of arterial oxygen saturation value after light exercise, could be a convenient means of estimating the level of high-altitude acclimatization among healthy subjects.