P1.088: Congenital Diaphragmatic Hernia in Very Preterm Infants: A National Study on Demographics and Outcomes

Background: Although clinical outcomes for preterm infants have improved in recent years, the specific impact of severe prematurity on infants with congenital diaphragmatic hernia (CDH) remains uncertain. The aim of our study was to analyze national data on preterm infants with CDH in Canada, with a focus on patient characteristics and management of very preterm infants (≤32 weeks of gestation, GW).

Methods: Following ethical approval (IRB#1000081647), we conducted a retrospective cohort study by interrogating the Canadian Pediatric Surgery Network (CAPSNet) registry, a national database on CDH patients from all Canadian pediatric surgical centers. Infants with CDH between 2006 and 2022 were identified. Outcome measures for very preterm babies were analyzed, including demographics, treatment strategies, and clinical outcomes. Data are reported as mean±SD or median (interquartile range) as indicated by normality testing.

Results: Incidence: Of the 1006 patients with CDH, there were 175 (17%) preterm liveborn infants, 43 (25%) of whom were ≤32GW. This did not include 26 (13%) fetuses who were terminated at a mean gestational age of 23.1±2.9 weeks, nor 5 (2%) stillborn (30.9±6.3GW) infants.
Demographics: Preterm infant ( < 37GW) characteristics are in Table 1. Very preterm infants (≤32GW) with CDH had a mean gestational age of 29.8±2.6GW and a mean birth weight of 1489±464g. Prenatal diagnoses were reported in 72% of cases. There was a marked male predominance among very preterm infants with CDH (74%) and a high prevalence of associated congenital anomalies (47%), most being congenital heart defects.
Treatment strategies: Surgical diaphragmatic repair was performed in 60% of very preterm infants with a mean time to surgery of 11.4±11.6 days from birth and a minimally invasive approach in only 15%. At least one post-operative complication was found in 50% of very preterm babies. The median duration of post-operative invasive ventilation was 11 days (IQR 11.5). No patients underwent treatment with extracorporeal life support.
Clinical Outcomes: The survival rate was 65% and 51% for preterm ( < 37GW) and very preterm (≤32GW) infants, respectively. Among the very preterm infant deaths, 4 died in transport prior to reaching a level III NICU, and 5 died post-operatively. Very preterm infants had a mean time to enteral feeds of 38.4±19 days, mean time to NICU discharge of 65±43.9 days and comorbidities at discharge were reported in 55%. Only 46% of very preterm babies were discharged without respiratory support.

Conclusion: To the best of our knowledge, this is the first nation-wide analysis of very preterm infants with CDH. This study highlights that despite advancements in the treatment of CDH, very preterm babies are particularly fragile, with high mortality rates that are possibly due to the inability to deliver extracorporeal life support. Nonetheless, most very preterm infants survive post-operatively with a substantial rate of comorbidities at discharge.