P2C139: Ventilation with an Intact Cord - How Long Is Too Long?

Background: The timing of physiological or delayed cord clamping continues to be a subject of ongoing debate. Is it possible to keep the umbilical cord intact in a preterm infant for longer duration especially when they are asphyxiated?
Our objective in this pilot study was to determine if placental transfusion from both umbilical vein & artery could be kept open for 2 hours. We wanted to study the effect of prolonged delayed cord clamping with ventilation (PDCCV – 2 hours) & early cord clamping with ventilation (ECCV) in an asphyxiated ovine preterm model on a) Net umbilical blood flows: Umbilical venous and umbilical arterial; b) Gas exchange, oxygen exposure, hemodynamics.

Methods: Using a surfactant deficient preterm model (125-126d preterm lambs ≡ < 28 week gestation), asphyxia was induced by umbilical cord occlusion until the heart rate (HR) was < 90 bpm. Post asphyxia, in ECCV - cord was clamped immediately and positive pressure ventilation (PPV) was initiated with supplemental oxygen as per neonatal resuscitation program. In the experimental group - PDCCV- umbilical cord was intact for 2 hours, PPV was initiated and continued. During PDCCV, the ewe with an intact placenta; was under general anesthesia with 100% oxygen for the entirety of 2 hours. Preductal oxygen saturation, oxygen exposure, blood gas, pulmonary/systemic hemodynamics were recorded for the 2 hours post resuscitation.

Results: A total of 10 lambs (4 from PDCCV & 6 from ECCV) were included. All 4 lambs in the PDCCV group were ventilated with an intact umbilical cord for 2 hours. Preductal saturations, supplemental oxygen, arterial oxygenation and pulmonary blood flow were significantly different between the groups. Arterial carbon dioxide and carotid blood flow was lower in PDCCV compared to ECCV.

Conclusion: In an asphyxiated preterm model, resuscitation with delayed cord clamping for 2 hours was feasible, with the net positive umbilical flow, improved oxygenation, higher pulmonary blood flow, and gradual increase in carotid blood flow . The factors such as asphyxia, PPV, arterial oxygen did not lead to umbilical cord occlusion in our study. Future translational/clinical studies to understand the reason for physiological umbilical cord closure are needed.