Does the Cardiothymic-Thoracic Ratio in Very Low Birth Weight Infants Indicate the Risk of Developing Bronchopulmonary Dysplasia?

INTRODUCTION: Fetal systemic inflammatory response triggered by infection and inflammation in preterm infants contributes to bronchopulmonary dysplasia (BPD) and preterm delivery. This study aims to determine whether there is a relationship between small thymus size and the risk of developing BPD.
METHODS: The cardiothymic/thoracic (CT/T) ratio was measured on AP chest X-ray obtained within the first 6 hours of life in very low birth weight (VLBW) infants weighing less than 1500 g between 2018 and 2023. Clinical information was collected independently from electronic medical records by two neonatologists. The demographic data of the infants included gestational age, mode of delivery, gender, birth weight, and Apgar scores at 5 and 10 minutes.
RESULTS: A total of 195 VLBW newborns (102 boys, 93 girls) were included in the study. The mean gestational age was 28.5 weeks, and the mean birth weight was 1074 grams. There was a statistically significant difference in the incidence rates of BPD by gestational age. The risk of BPD was 6.702 times higher in babies born weighing less than 1000 grams. The CT/T ratio was significantly lower in infants who developed BPD compared to those who did not.
DISCUSSION AND CONCLUSION: The thymus is an essential organ for the immune system. In our study, the finding that lower birth weight and gestational age were associated with a smaller CT/T ratio suggests a higher rate of inflammation, leading to increased morbidity and mortality. Identifying preterm infants with a small thymus may help clinicians recognize those at high risk for developing BPD.