Individual variations and sex differences in hemodynamics with percutaneous arterial oxygen saturation (SpO₂) in...

Many studies have reported specific adaptations to high altitude, but few studies have focused on physiological variations in high-altitude adaptation in Andean highlanders. This study aimed to investigate the relationships between SpO₂ and related factors, including individual variations and sex differences, in Andean highlanders.

The participants were community-dwelling people in La Paz, Bolivia, aged 20 years and over (age range 20-34 years). A total of 50 men and 50 women participated in this study. Height, weight, SpO₂, hemoglobin concentration, finger temperature, heart rate, and blood pressure were measured. Information about lifestyle was also obtained by interview.

There were individual variations of SpO₂ both in men (mean 89.9%, range 84.0-95.0%) and women (mean 91.0%, range 84.0-96.0%). On Student's t test, men had significantly lower heart rate (p = 0.046) and SpO₂ (p = 0.030) than women. On the other hand, men had significantly higher SBP (p < 0.001), hemoglobin (p < 0.001), and finger temperature (p = 0.004). In men, multiple stepwise regression analysis showed that a higher SpO₂ was correlated with a lower heart rate (β = - 0.089, p = 0.007) and a higher finger temperature (β = 0.308, p = 0.030) (r² for model = 0.18). In women, a higher SpO₂ was significantly correlated with a higher finger temperature (β = 0.391, p = 0.015) (r² for model = 0.12). A higher SpO₂ was related to a higher finger temperature (β = 0.286, p = 0.014) and a lower heart rate (β = - 0.052, p = 0.029) in all participants (r² for model = 0.21). Residual analysis showed that individual SpO₂ values were randomly plotted.

Random plots of SpO₂ on residual analysis indicated that these variations were random error, such as biological variation. A higher SpO₂ was related to a lower heart rate and finger temperature in men, but a higher SpO₂ was related to finger temperature in women. These results suggest that there are individual variations and sex differences in the hemodynamic responses of high-altitude adaptation in Andean highlanders.