Identifying Neonatal and Pediatric Cardiac and Congenital Diaphragmatic Hernia Extracorporeal Membrane Oxygenation Patients at Increased Mortality Risk

Abstract

A previous review from our institution established clinically measured cut-points that defined the late implementation of extracorporeal membrane oxygenation (ECMO) correlating to increased mortality in neonatal and pediatric respiratory patients. Using the same methods, this review evaluates pediatric and neonatal cardiac and congenital diaphragmatic hernia (CDH) patients to determine if the same cut-points exist in this higher risk patient population. Neonatal and pediatric cardiac and CDH patients placed on ECMO between November 1989 and December 2008 were retrospectively reviewed to determine the first adjusted anion gap (AGc), the first venoarterial carbon dioxide (CO2) gradient (p[v-a]CO2), and the first Viability Index (AGc + p[v-a]CO2= INDEX) on ECMO. These markers were then analyzed to identify the presence of specific cut-points that marked an increased risk of mortality. The timing of surgery was also reviewed to assess the surgical morbidity on survival. The review of neonatal and pediatric cardiac and CDH patients (n= 205) with an overall survival of 46% showed that all three markers were elevated to varying degrees in the expired patients (n= 110). Histograms identified the following specific cut-points for increased mortality: the AGc ≥ 23 mEq/L, the p[v-a]CO2≥ 16 mmHg, and the INDEX ≥ 28. An elevated AGc and INDEX correlated with a significantly higher risk for mortality (p< .05), survival to discharge being 20% or less. Patients under the cut-points had survival rates of 51% or higher. The timing of surgery (before or after ECMO initiation) did not significantly impact survival in the combined cardiac and CDH group. An INDEX ≥ 28 correlates with non-survival. We speculate that the late implementation of ECMO may lead to reperfusion injury, which causes reduced survival, and that ECMO intervention prior to reaching the cut-points may improve survival in neonatal and pediatric cardiac and CDH patients.