6593 Prediction of bronchopulmonary dysplasia by the chest radiographic thoracic area on day one in infants with exomphalos

Objectives Respiratory insufficiency is a significant cause of mortality and morbidity amongst infants with exomphalos and usually is ascribed to the increased intraabdominal pressure after surgical closure. We determined if infants with exomphalos also had abnormal antenatal lung growth as indicated by lower chest radiographic thoracic areas (CRTA) on day one compared to ventilated, term-born controls without respiratory pathology and whether the CRTA could predict the development of bronchopulmonary dysplasia (BPD). Methods Infants with exomphalos cared for between January 2004 and January 2023 were included in the study. The control group consisted of term, newborn infants admitted because of poor perinatal adaptation or hypoxic ischemic encephalopathy without concomitant respiratory pathology. The infants were ventilated for absent respiratory drive at birth and had no supplemental oxygen requirement by six hours of age. The study was registered with the Clinical Governance Department. The radiographs were imported as digital image files by Sectra PACS software (Sectra AB, Linköping, Sweden). Free-hand tracing of the perimeter of the thoracic area as outlined by the diaphragm and the rib cage was undertaken and the CRTA was calculated by the software. The chest radiograph with the highest CRTA in the first 24 hours after birth for each infant was included in the analysis. Results Sixty-four infants with exomphalos and 130 controls were included. Infants with exomphalos had a lower median (IQR) CRTA [1983 (1657 – 2471) mm2] compared to controls [2547 (2153 – 2932) mm2, p<0.001]. Infants with exomphalos had a lower median (IQR) gestational age [38.1 (35.8 – 39.0) weeks] and birth weight [3.06 (2.43 – 3.33) kg] compared to controls [39.5 (38.0 – 41.0) weeks and 3.34 (2.98 -3.69) kg, p<0.001 for both] and a lower incidence of male sex (42% versus 59%) p=0.032). Following multivariable regression analysis, infants with exomphalos had significantly lower CRTAS compared to controls (p=0.001) after adjusting for differences in gestational age and male sex. In the exomphalos group, the CRTA was lower in infants with exomphalos who developed BPD [n=14, 1530 (1307 – 1941) mm2] compared to those who did not [2168 (1865 – 2672), p<0.001]. Following multivariable regression analysis, the CRTA was significantly associated with BPD development [p=0.021] after adjusting for male sex and gestational age. Conclusion The lower CRTA on day one in the exomphalos infants compared to the controls and its association with BPD development suggests the exomphalos infants may have had abnormal antenatal lung development.