Abnormal Blood Gas and Oxygen Requirements in First 24 Hours of Life as Indicators of Morbidity in Very Low Birth Weight Infants

Background: Oxygen requirement as well as abnormal blood gas values have often been used as indicators of morbidity in the premature neonate, however, there is mixed evidence regarding its utility to predict future short and long term morbidity. This study aims to assess the impact of abnormal pCO2, pH, and FiO2 values in the first 24 hours of life of very low birth weight (VLBW) infants on short and long term outcomes.

Methods: Data on all VLBW infants was retrospectively gathered from the electronic medical record between the years of 2009 and 2021. IRB approval was obtained prior. For blood gas levels, significance was calculated based on pH of 7.15 and CO2 of 50 mm Hg. FiO2 was considered significant if the infant required 50% in the first 24 hours of life. Each category was statistically analyzed against common neonatal outcomes including intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), and retinopathy of prematurity (ROP).

Results: Of 564 VLBW infants studied 46.6% had an abnormal pCO2 and 53.4% had a normal pCO2. 78.7% of these infants had an abnormal pH and 19.5% had a normal pH. 87.2% had a normal FiO2 and 12.8% had an abnormal FiO2. Infants with elevated pCO2, decreased pH, and high FiO2 were significantly more likely to need intubation in the delivery room, emergently, remained intubated at 24 hours and had significantly higher days of invasive mechanical ventilation (Table I). These infants were more likely to need surfactant and had higher mortality (Table I). Lastly, these infants were at increased risk of IVH and ROP (Table I). BPD was correlated with higher FiO2 as well as low pH. Neonates with abnormal FiO2 also showed an increased risk for having abnormal MRI before discharge (51.6% vs 69.0% p = 0.034).

Conclusion: Abnormal blood gas and higher FiO2 in the first 24 hours of life is associated with increased need for intubation as well as invasive mechanical ventilation in the delivery room and NICU. VLBW infants showed increased likelihood of developing long term complications including BPD, severe IVH, and severe ROP.