Oxygen saturation reference ranges and factors affecting SpO₂ among children living at altitude

To determine reference values for oxygen saturation (SpO₂) among healthy children younger than 5 years living at moderately high altitude in Papua New Guinea and to determine other factors that influence oxygen saturation levels.

266 well children living at 1810-2630 m above sea level were examined during immunisation clinic visits, and SpO₂ was measured by pulse oximetry. Potential risk factors for hypoxaemia were recorded and analysed by multivariable analysis.

The median SpO₂ was 95% (IQR 93%-97%), with a normal range of 89%-99% (2.5-97.5 centiles). On multivariable analysis, younger children, children of parents who smoked, those asleep and babies carried in bilums, a traditional carry bag made of wool or string, had significantly lower SpO₂.

The reference range for healthy children living in the highlands of Papua New Guinea was established. Besides altitude, other factors are associated with lower SpO₂. Some higher-risk infants (preterm, very low birth weight, recurrent acute lower respiratory infection or chronic respiratory problem) may be more prone to hypoxaemia if they have additive risk factors: if parents smoke or they are allowed to sleep a bilum, as their baseline oxygen saturation may be significantly lower, or their respiratory drive or respiratory function is impaired. These findings need further research to determine the clinical importance.