Reference values for pulse oximetry at high altitude

OBJECTIVE To determine reference values for oxygen saturation (Sao 2) in healthy children younger than 5 years living at high altitude. DESIGN One hundred and sixty eight children were examined for Sao 2 at 4018 m during well child visits. Physiological state was also noted during the examination. RESULTS The mean Sao 2 was 87.3% (95% confidence intervals (CI) 86.7%, 87.9%) with a median value of 87.7%. A significant difference was observed in Sao 2 between children younger than 1 year compared with older children, although the difference was no longer demonstrable when sleeping children were excluded. CONCLUSIONS This study has provided a reference range of Sao 2 values for healthy children under 5 years old so that pulse oximetry may be used as an adjunct in diagnosing acute respiratory infections. Younger children were also shown to have a lower mean Sao 2 than older children living at high altitude, which suggests physiological adaptation to high altitude over time. In addition, sleep had a lowering effect on Sao 2, although the clinical importance of this remains undetermined.