Effect of timing of umbilical cord clamping on cerebral tissue oxygen saturation in term and preterm infants

脐带夹紧是最古老的医疗程序之一。然而，夹紧脐带的最佳时间仍不确定。有证据表明，延迟脐带夹紧（90 ~ 180秒）可提高早产儿无脑出血的存活率。延迟脐带夹紧后胎盘输血导致的新生儿血容量增加被认为是早产儿获益的主要原因。然而，没有足够的证据表明延迟脐带夹紧对足月婴儿有益，早期脐带夹紧仍然是足月和近足月婴儿的标准做法。众所周知，大多数足月婴儿出生后不久就会啼哭和呼吸，即在脐带夹住之前。过早夹紧脐带（< 20秒）可能导致婴儿第一次呼吸前胎盘循环中断，阻止生理适应，并可能导致心血管疾病。在一项足月和早产儿前瞻性随机对照试验的框架内，本研究将回答哪个时间是最好的夹脐带：早期夹脐带（< 20 s），延迟夹脐带（90 ~ 180 s）或呼吸后10 s夹脐带。主要和关键的次要结局指标将是心动过缓（心率< 100 bpm）、动脉血氧饱和度和脑组织氧合的发生率。本研究结果将有助于更好地了解胎儿到新生儿过渡的生理过程。此外，在早期脐带夹紧的婴儿群体中获得了生命前10分钟内心率和血氧饱和度的既定参考范围。这些研究需要重复，以确定脐带夹紧的时间是否会影响这些参考范围。这项研究的发现可能会改变国际复苏指南。

Umbilical cord clamping is one of the oldest medical procedures. However, the best time to clamp the cord remains uncertain.There is evidence that delayed cord clamping (90 to 180 s) improves the chances of survival without cerebral hemorrhage in preterm infants. The increased blood volume of the newborn resulting from placental transfusion after delayed cord clamping is thought to be the primary cause for the benefits observed in preterm infants. However, there is insufficient evidence of a beneficial effect of delayed cord clamping in term infants, and early cord clamping continues to be standard practice in term and near term infants.It is well known that most term infants cry and breathe soon after birth, I.e. before the umbilical cord is clamped. Early cord clamping (< 20 s) may result in a disruption of placental circulation before the infant takes its first breath, preventing physiological adaptation and possibly leading to cardiovascular disturbances.Within the framework of a prospective randomized controlled trial in term and preterm infants, this study will answer the question of which time of cord clamping is best: early cord clamping (< 20 s), delayed cord clamping (90 to 180 s) or cord clamping 10 s after breathing is established. Primary and key secondary outcome measures will be the incidence of bradycardia (heart rate < 100 bpm), arterial oxygen saturation and cerebral tissue oxygenation. The findings of this study will help to better understand the physiological processes during fetal to neonatal transition. Moreover, the established reference ranges for heart rate and oxygen saturations within the first 10 min of life were obtained in a population of babies undergoing early cord clamping. These studies need to be repeated to determine whether the timing of cord clamping influences these reference ranges. Findings from the proposed study may alter international resuscitation guidelines.