Gestational Age as a Predictor of Oxygen Needs and ABG Patterns in Preterm Neonates with RDS: Evidence from a Resource-Limited NICU in Pakistan

Background: Respiratory Distress Syndrome (RDS) remains a leading cause of morbidity and mortality among premature infants. Their immature lungs lack surfactant, making breathing difficult. These infants need close monitoring with arterial blood gas (ABG) checks to guide oxygen therapy. While gestational age is known to influence disease severity, locally relevant data on oxygen requirements and arterial blood gas (ABG) changes across gestational age groups remain scarce in Pakistan. Objective: To evaluate gestational age-related variations in oxygen demand, ABG parameters, and respiratory support among preterm neonates with RDS, with the goal of identifying physiologic and management differences that may guide tailored interventions in low-resource NICU settings. Methodology: This four-month cross-sectional study was conducted in the NICU of the University of Lahore Teaching Hospital, Pakistan. Sixty-five preterm neonates (28-36 weeks) with RDS were enrolled through consecutive sampling. Data on gestational age, oxygen requirement (FiO2), mode of respiratory support, and ABG parameters were collected before and after stabilization on respiratory support. Data were analyzed in SPSS 27 using ANOVA, Kruskal-Wallis, Chi-square, paired t-tests, and Spearman's correlation. Results: Lower gestational age was linked to higher oxygen needs (FiO2 83% at 28-30 weeks vs. 55% at 34-36 weeks, p < 0.001) and more invasive ventilation (60% vs. 10%, p = 0.011). ABG parameters correlated significantly with gestational age: earlier gestations had lower pH, higher PaCO2, and lower PaO2 and SaO2 (all p < 0.05), while HCO3 showed no correlation (p = 0.316). Despite stabilization, SaO2 values remained below the target 90-94% range in all groups. Conclusion: Gestational age is a key predictor of oxygen needs, ABG derangements, and intensity of respiratory support in preterm neonates with RDS. This first locally relevant evidence from Pakistan underscores the need for gestation-specific oxygen protocols to improve care in resource-limited NICUs and similar low-resource settings worldwide.