Abstract
Hypoxemia is a major life-threatening complication of childhood pneumonia. The threshold points for hypoxemia vary with altitude. However, few published data describe that normal range of variation. The purpose of this study was to establish reference values of normal mean Sao(2) levels and an approximate cutoff point to define hypoxemia for clinical purposes above 4300 meters above sea level (masl). Children aged 5 to 16 yr were examined during primary care visits at the Huayllay Health Center. Huayllay is a rural community located at 4340 m in the province of Pasco in the Peruvian Andes. We collected basic sociodemographic data and evaluated three outcomes: arterial oxygen saturation (Sao(2)) with a pulse oximeter, heart rate, and respiratory rate. Comparisons of main outcomes among age groups (5-6, 7-8, 9-10, 11-12, 13-14, and 15-16 yr) and sex were performed using linear regression models. The correlation of Sao(2) with heart rate and respiration rate was established by Pearson's correlation test. We evaluated 583 children, of whom 386 were included in the study. The average age was 10.3 yr; 55.7% were female. The average Sao(2), heart rate, and respiratory rate were 85.7% (95% CI: 85.2-86.2), 80.4/min (95% CI: 79.0-81.9), and 19.9/min (95% CI: 19.6-20.2), respectively. Sao(2) increased with age (p < 0.001). No differences by sex were observed. The mean minus two standard deviations of Sao(2) (threshold point for hypoxemia) ranged from 73.8% to 81.8% by age group. At 4300 m, the reference values for hypoxemia may be 14.2% lower than at sea level. This difference must be considered when diagnosing hypoxemia or deciding oxygen supplementation at high altitude. Other studies are needed to determine whether this reference value is appropriate for clinical use.