Reference Interval for SPO2 in Neonates at High Altitudes During First 2 Hours and Umbilical Artery Blood Gas

Pulse oximetry offers real time and non-invasive estimation of arterial oxygen saturation in a cost-effective way, and has become a critical tool in guiding the usage of supplemental oxygen in sick newborns. During postnatal transition, pulmonary pressure decreases upon the activation of the lungs, and the ductus arteriosus constricts and closes upon the increase of partial oxygen pressure, which is negatively correlated with altitude. As a result, postnatal transition may be different at high altitudes. Umbilical cord blood gas analysis is now recommended in all high-risk deliveries because of its' value in providing information about preceding fetal hypoxic stress. But there are only limited studies about the SpO2 measurements during the first few hours after birth and umbilical blood gas analysis at high altitudes, especially at altitudes above 2500m. The primary outcome of the study is to determine the reference intervals for preductal oxygen saturation during first 2 hours of life stratified by different gestational age. The secondary outcomes is to establish the pH and lactate cutoff value of umbilical arterial blood gas at different altitude level.