Effect of delayed cord clamping and cord milking on cerebral oxygenation and cardiovascular function: a secondary analysis of the PCI trial

Umbilical cord clamping management may affect cerebral oxygenation (rSO₂C), but previous studies have only investigated effects in the first minutes of life. Our objective was to determine whether delayed cord clamping (DCC) and umbilical cord milking (UCM) differently affect cerebral oxygenation and cardiovascular function in the first 24 h of life in preterm infants. A post-hoc secondary outcome analysis of a multicentre prospective randomised clinical trial (PCI), conducted between April 2016 and February 2023 at 8 Italian neonatal intensive care units. The present ancillary study included preterm infants with 23⁺⁰-29⁺⁶ 30 weeks' gestation. One hundred and five infants received DCC and 104 UCM during resuscitation. Cerebral regional tissue oxygenation (rSO₂C) was measured by near-infrared spectroscopy (NIRS) at 3 (T_3h), 6 (T_6h), 12 (T_12h), 18 (T_18h), and 24 (T_24h) hours of life. Cardiovascular function was assessed by echocardiography within the first 24 h of life. We found that rSO₂C was higher at T_3h [79 (76-84) vs. 78% (74-82), P = 0.04)] and T_12h [79 (76-83) vs. 78% (74-80), P = 0.01] in the DCC than in the UCM group. Left ventricular output (LVO) was lower [196 (182-301) vs. 232 (182-301) ml/Kg/min, P = 0.02] in the DCC than in the UCM group, while right ventricular output (RVO) and superior vena cava (SVC) flow were similar. The need for dopamine was higher (26 vs. 23%, P = 0.02) in the in the DCC than in the UCM group.Conclusion: rSO₂C was transiently higher in preterm infants resuscitated with DCC in comparison with UCM, but this difference was not clinically relevant. The lower LVO value in the DCC group compared to the UCM group deserves further studies to be confirmed and interpreted.