The Usefulness of Thymic Size at Birth as a Predictor of Bronchopulmonary Dysplasia

ABSTRACT

PURPOSE: Recent studies show that chorioamnionitis has an important role in the pathogenesis of bronchopulmonary dysplasia(BPD) and it induces thymic involution. The purpose of this study is to test the usefulness of thymic size at birth as a predictor of BPD. METHODS: This study was conducted on 91 very low birth weight infants of <1, 500 g with mean gestational age of 29.3 weeks and mean birth weight of 1, 161 g who were admitted at NICU of Dong Kang General Hospital for past 4 years of whom 21 infants had BPD. Thymic size was measured on routine chest radiographs taken in the first 3 hours after birth and measured as the ratio between the width of the cardiothymic shadow at the level of the carina and that of the thorax at the costophrenic angles (CT/ T). RESULTS: Correlation of thymic size with gestational age was statistically significant (P=0.003). CT/T of BPD group was smaller than that of non-BPD group (0.27+/-0.06, 0.33+/-0.07, respectively, P<0.01). A significant positive correlation between small thymus at birth and BPD was detected (P=0.003, odds ratio, 21.7), but not in other disease groups. CONCLUSIONS: We concluded that a small thymus at birth on the chest radiograph could be used as an early predictive parameter of the BPD.