Association between base excess levels and clinical outcomes among very low birth weight infants: a multicenter birth cohort study in South Korea

Background: The impact of metabolic acidosis on short-term outcomes and mortality in very low birth weight infants (VLBWIs) has not been well studied. Purpose: To investigate the potential association between metabolic acidosis and the clinical outcomes of VLBWIs in South Korea. Methods: Between 2013 and 2019, data were collected from the Korean Neonatal Network, which covers a multicenter birth cohort spanning 75 hospitals. Our study cohort included 14,519 infants with a birth weight of less than 1,500 g who were admitted to the neonatal intensive care unit. Blood gas measurements taken within 1 hour of birth were used to evaluate the clinical outcomes, which were categorized into 5 groups according to base excess (BE) levels. We assessed respiratory outcomes, neurological morbidities, and infection-related and gastrointestinal outcomes along with mortality rates. Results: We analyzed 10,394 VLBWIs based on the inclusion criteria. A BE level below -9 suggested a significantly high risk of various respiratory outcomes, including air leak syndrome (adjusted odds ratio [aOR], 2.071; 95% confidence interval [CI], 1.305-3.285), massive pulmonary hemorrhage (aOR, 2.317; 95% CI, 1.502-3.575), pulmonary hypertension (aOR, 2.296; 95% CI, 1.667-3.161), and neonatal respiratory distress syndrome (aOR, 2.219; 95% CI, 1.778-2.769). These infants also exhibited an elevated risk of neurological (aOR, 2.797; 95% CI, 2.314-3.380), infection-related (aOR, 2.082; 95% CI, 1.653-2.623), gastrointestinal (aOR, 1.979; 95% CI, 1.408-2.783), and mortality (aOR, 2.683; 95% CI, 2.076-3.466) outcomes. Conclusion: Our findings highlight the potential effect of metabolic acidosis at birth on the clinical outcomes of VLBWIs. A strong correlation was observed between metabolic acidosis and neurological morbidity. These findings offer important insights for managing VLBWIs with metabolic acidosis and suggest the need.