Oxygen saturation and heart rate in healthy school children and adolescents living at high altitude

This study was conducted to establish reference values for percent oxygen saturation of hemoglobin (SaO₂, %) and heart rate (HR, bpm) in children living at high altitude (4,100 m) and to relate possible differences in the variables with ethnic origin. Healthy children from a mine-located school (Tintaya, n = 417), a nearby school (Marquiri, n = 474), and a rural Andean community (Nuñoa, n = 373) were investigated. The samples included different ethnic combinations, with the Nuñoa children having a predominant Quechua ancestry. Mean SaO₂ for all ages was substantially lower in all high altitude children compared to values considered normal for sea level. Among the three samples, SaO₂ was higher (91.3 ± 2.7) and HR was lower (84.8 ± 13.6) in Nuñoa than in Tintaya (SaO₂, 89.8 ± 2.5; HR, 91.7 ± 14.9) and Marquiri (SaO₂, 89.6 ± 3.1; HR, 88.5 ± 12.9) (P < 0.05). There was no sex difference and only a weak age-dependent trend for SaO₂. Values considered abnormal at sea level were observed in all healthy high-altitude children. Higher SaO₂ and lower HR in Nuñoa children may suggest a better degree of acclimatization to altitude.