Oxygen saturation by pulse oximetry in healthy infants at an altitude of 1610 m (5280 ft). What is normal?

Pulse oximetry is a valuable, noninvasive technique for assessing oxygen saturation that has gained wide clinical acceptance despite little available information concerning normal values in the newborn, especially at an altitude different than sea level. We performed serial pulse oximetry studies on 150 term, appropriate-weight-for-gestational-age, clinically healthy infants at an altitude of 1610 m (5280 ft) at 24 to 48 hours, 1 month, and 3 months of age to define a reference range for oxygen saturation as a guideline in clinical care. We found that mean oxygen saturation at 24 to 48 hours of age is 92% to 93% and varies little with infant activity. With increasing postnatal age, there is a tendency for increased oxygen saturation during the awake states to 93% to 94%, while oxygen saturation during sleep stays the same or even decreases slightly. The lower end of the reference range (2 SDs below the mean) is as low as 85% during feeding at 24 to 48 hours of age, and as low as 86% during quiet sleep at 1 and 3 months of age, with 88% to 89% the lower limit in other activities at all ages.