Arterial blood gases and ventilation at rest by age and sex in an adult Andean population resident at high altitude.

ABSTRACT

PURPOSE: Arterial blood gases (ABG) are influenced by the altitude above sea level, age and sex. Most studies have been conducted at sea level and in small populations ascending to or residents at very high altitudes. Our objective was to evaluate the ventilation and ABG by age and sex in an Andean population resident at high altitude (2640 m). METHODS: Analytical cross-sectional study was done in healthy volunteers. ABG and minute ventilation (VE) were measured. T test and ANOVA for differences by sex and age, and Pearson test for correlations between age, VE and ABG were performed. RESULTS: We included 374 adults, 55% women from 18 to 83 years and hemoglobin of 15.7 ± 1.6 g/dl. There was a significant decrease in PaO2 and SaO2 and an increase in P(A - a)O2 with age (p < 0.001). Unlike men, with age women had a significant increase in PaCO2 and a higher decrease in PaO2. The correlations between age, the decrease in PaO2 and the increase in PaCO2 were greater in women than in men. The VE adjusted to body surface area decreased with age, but this correlation was significantly higher in women. CONCLUSIONS: In this study, with a considerable number of healthy adults living at high altitude (2640 m), we established the physiological impact of altitude, aging and gender in ABG. The PaO2 and PaCO2 were significantly lower and the hemoglobin values slightly higher than described at sea level. In addition to PaO2 decline with age, there was an age-related increase in PaCO2 in women, associated with a greater reduction of VE.