Differential Alveolar and Systemic Oxygenation during Preterm Resuscitation with 100% Oxygen during Delayed Cord Clamping

Objective Delayed cord clamping (DCC) and 21 to 30% O ₂resuscitation is recommended for preterm infants but is commonly associated with low pulmonary blood flow (Qp) and hypoxia. 100% O ₂supplementation during DCC for 60 seconds followed by 30% O ₂may increase Qp and oxygen saturation (SpO ₂). Study Design Preterm lambs (125-127 days of gestation) were resuscitated with 100% O ₂with immediate cord clamping (ICC, n = 7) or ICC + 30% O ₂, and titrated to target SpO ₂(n = 7) or DCC + 100% O ₂for 60 seconds, which followed by cord clamping and 30% O ₂titration (n = 7). Seven preterm (23-27 weeks of gestation) human infants received continuous positive airway pressure (CPAP) + 100% O ₂for 60 seconds during DCC, cord clamping, and 30% O ₂supplementation after cord clamping. Results Preterm lambs in the ICC + 100% O ₂group resulted in PaO ₂(77 ± 25 mm Hg), SpO ₂(77 ± 11%), and Qp (27 ± 9 mL/kg/min) at 60 seconds. ICC + 30% O ₂led to low Qp (14 ± 3 mL/kg/min), low SpO ₂(43 ± 26%), and PaO ₂(19 ± 7 mm Hg). DCC + 100% O ₂led to similar Qp (28 ± 6 mL/kg/min) as ICC + 100% O ₂with lower PaO ₂. In human infants, DCC + CPAP with 100% O ₂for 60 seconds, which followed by weaning to 30% resulted in SpO ₂of 92 ± 11% with all infants >80% at 5 minutes with 100% survival without severe intraventricular hemorrhage. Conclusion DCC + 100% O ₂for 60 seconds increased Qp probably due to transient alveolar hyperoxia with systemic normoxia due to dilution by umbilical venous return. Larger translational and clinical studies are warranted to confirm these findings. Key Points Transient alveolar hyperoxia during delayed cord clamping can enhance pulmonary vasodilation. Placental transfusion buffers systemic oxygen tension and limits hyperoxia. Use of 100% oxygen for 60 seconds during DCC was associated with SpO ₂≥80% by 5 minutes.