279 - Early echocardiographic markers following delayed cord clamping with high or low oxygen in extremely low gestation infants

Poster Number: 279
Publication Number: 279.3010

Background: Delayed cord clamping (DCC) has been shown to reduce mortality in extremely low gestation age neonates (ELGAN) but not reduce other morbidities such as severe intraventricular hemorrhage (sIVH). This may be due to inadequate breathing and its resultant hypoxia during transition. A brief use of 100% oxygen during delayed cord clamping may improve oxygenation by promoting airway opening, lung aeration and pulmonary vasodilation. Cardiac function may improve because of lowered pulmonary vascular resistance (PVR), reduced RV afterload and increased LV preload.

Objective: To determine if providing high oxygen support (100%) during 90 seconds of DCC compared to low oxygen support (30%) improves right ventricular hemodynamics including right ventricular output, tricuspid regurgitation, and pulmonary acceleration time to right ventricular ejection time (PAAT:RVET). Secondary outcomes include additional markers of PVR, cardiac output, and myocardial contractility.

Design/Methods: This preplanned sub-study of our larger blinded randomized controlled trial compared preterm neonates 23+0 to 27+6 weeks’ gestation who received continuous positive airway pressure (CPAP) or positive pressure ventilation (PPV) support with 100% (HI) or 30% (LO) oxygen with an intact cord for 90 seconds. After cord clamping, neonates were transferred to a warmer and resuscitated per standard guidelines with 30% oxygen and titrated to achieve target SpO2. An echocardiogram was done around 6 hours of life including flow doppler, speckle tracking strain measures, and tissue doppler.

Results: 78 neonates were randomized in the sub-study and underwent early echocardiography (37 in HI group, 41 in LO group). Outcome data are not yet available for the primary study. Baseline maternal, delivery, and infant characteristics were equal between both groups (Table 1). RVO, tricuspid velocity jet, and other markers of cardiac output were similar, but pulmonary artery acceleration time to right ventricular ejection (PAAT:RVET) was higher in the HI group (0.28 ± 0.09 vs. 0.24 ± 0.07; p = 0.04). There were no major differences in tissue doppler markers of ventricular function.

Conclusion(s): Our results suggest 100% oxygen during DCC improves early pulmonary hemodynamics in extremely preterm infants compared to 30% oxygen. This degree of oxygen exposure with an intact cord may avoid detrimental effects to other components of cardiac function. Once results from the ongoing clinical trial are available, we will assess whether these physiological findings are associated with improved clinical outcomes.