Oxygenation Indices with Oxygen Challenge Test in Neonates During VA ECMO

Objective: To evaluate the response of various oxygenation indices to the oxygen challenge test (OCT), prior to decannulation, in neonates supported with VA ECMO for respiratory indications, and to compare these responses between survivors and non-survivors. Design: Single-center retrospective observational study. Setting: Single, tertiary care, 40-bed Pediatric Intensive Care Unit in Miami, Florida. Patients: Neonates cannulated to VA ECMO for respiratory failure from 2012 to 2022 who had an OCT. Patients with congenital heart disease were excluded. Measurements and Main Results: A total of 63 neonates were included, of whom 13 patients died (20.6%). Oxygenation indices compared before and during OCT include PaO2, Delta PaO2, P/F ratios, Alveolar-arterial gradient, arterial/alveolar ratios, and shunt fraction. The Wilcoxon signed-rank test demonstrated increases in all oxygenation indices during OCT compared to pre-OCT, except for P/F ratios. There were no differences in oxygenation indices between survivors and non-survivors during OCT. However, after decannulation, all oxygenation indices were worse in non-survivors (p < 0.05). Linear regression analysis demonstrated that delta FiO2 on the ventilator, P/F before OCT, and ECMO flow during OCT significantly affected PaO2 response during OCT. Shunt fraction above 28.8% after decannulation demonstrated the highest discriminatory ability for mortality (AUC 0.853). Conclusions: The OCT response during ECMO is not a reliable predictor of survival in neonates on VA ECMO, and its value in assessing readiness for ECMO trial-off warrants further evaluation. Further studies investigating the role of oxygenation indices at the time of trial-off for predicting outcomes may be helpful.