Establishing the reference interval for pulse oxygen saturation in neonates at high altitudes: protocol for a multicentre, open, cross-sectional study.

INTRODUCTION: Establishing the reference interval for pulse oxygen saturation (SpO2) is essential for sensitively identifying neonatal hypoxaemia due to various causes. However, the reference interval for high altitudes has not yet been established, and existing studies have many limitations. This study will aim to establish the reference interval for various high altitudes and determine whether preductal and postductal measurements at the same altitude vary. METHODS AND ANALYSIS: This is a multicentre, open, cross-sectional study, which will begin in February 2022. Approximately 2000 healthy full-term singleton neonates will be recruited from six hospitals (altitude ≥2000 m) in Qinghai Province, China. The participating hospitals will use a uniform pulse oximeter type. The measurements will be performed between 24 hours after birth and discharge. During the measurement, the neonate will be awake and quiet. Preductal and postductal measurements will be performed. The measurement time, site and results will be recorded and input, along with the collected basic information, into the perinatal cloud database. We will carry out strict quality control for basic information collection, measurement and data filing. We will perform descriptive statistics on the distribution range of the collected data, determine the lower limit value of the reference interval for each hospital and the corresponding altitude, perform curve fitting for the lower limit value, use the altitude as a covariate for the function corresponding to the fitted curve, establish the prediction equation and ultimately determine the reference intervals of each high altitude location. ETHICS AND DISSEMINATION: Our protocol has been approved by the Medical Ethics Committee of all participating hospitals. We will publish our study results in academic conferences and peer-reviewed public journals. TRIAL REGISTRATION NUMBER: NCT05115721.

Surfactant Therapy for Respiratory Distress Syndrome in High- and Ultra-High-Altitude Settings.

Objective: The objective of this study is to investigate the therapeutic effect of surfactant replacement therapy (SRT) on respiratory distress syndrome (RDS) in premature infants in the Qinghai-Tibet Plateau. Materials and Methods: This multi-center retrospective cohort study collected and screened reasonable clinical data of 337 premature infants with RDS from 10 hospitals in the Qinghai-Tibet Plateau from 2015 to 2017. We grouped the cases by rationally analyzing their baseline characteristics, using logistic analysis to evaluate each factor's effect on the prognosis of the infants, and comparing the short-term improvement in blood gas and mortality after SRT treatment at different altitudes, in high-altitude (1,500-3,500 m) and ultra-high-altitude (3,500-5,500 m) groups. Results: Independent of altitude, the mortality rate of children with RDS in the SRT group was significantly lower than that of children in the non-SRT group (both P < 0.05). The effect of SRT on preterm infants with RDS in the high-altitude group [odds ratio (OR) = 0.44, 95% confidence interval (CI) = 0.22-0.87, P = 0.02] was better than that in the infants in the ultra-high-altitude group (OR = 0.26, 95% CI = 0.13-0.58, P < 0.01), with death rates of 34.34 and 49.71%, respectively. Similarly, after SRT, the improvement of PaO2/FiO2 and pH of children at high altitude was significantly better than those of children at ultra-high altitude (all P < 0.01). Conclusions: SRT plays a prominent role in curing infants with RDS in both high- and ultra-high-altitude regions, although with better effects at high rather than ultra-high altitude. This study provides a basis for further large-scale studies on SRT for RDS treatment at high altitudes.