Hooper Stuart B, Te Pas Arjan B, Lang Justin, van Vonderen Jeroen J, Roehr Charles Christoph, Kluckow Martin, Gill Andrew W, Wallace Euan M, Polglase Graeme R
1] The Ritchie Centre, MIMR-PHI Institute of Medical Research, Monash University, Clayton, Victoria, Australia [2] Department of Obstetrics and Gynecology, Monash University, Clayton, Victoria, Australia.
Department of Pediatrics, Leiden University Medical Centre, Leiden, The Netherlands.
Pediatr Res. 2015 May;77(5):608-14. doi: 10.1038/pr.2015.21. Epub 2015 Feb 4.
The transition to newborn life at birth involves major cardiovascular changes that are triggered by lung aeration. These include a large increase in pulmonary blood flow (PBF), which is required for pulmonary gas exchange and to replace umbilical venous return as the source of preload for the left heart. Clamping the umbilical cord before PBF increases reduces venous return and preload for the left heart and thereby reduces cardiac output. Thus, if ventilation onset is delayed following cord clamping, the infant is at risk of superimposing an ischemic insult, due to low cardiac output, on top of an asphyxic insult. Much debate has centered on the timing of cord clamping at birth, focusing mainly on the potential for a time-dependent placental to infant blood transfusion. This has prompted recommendations for delayed cord clamping for a set time after birth in infants not requiring resuscitation. However, recent evidence indicates that ventilation onset before cord clamping mitigates the adverse cardiovascular consequences caused by immediate cord clamping. This indicates that the timing of cord clamping should be based on the infant's physiology rather than an arbitrary period of time and that delayed cord clamping may be of greatest benefit to apneic infants.
出生时向新生儿期的过渡涉及由肺通气引发的重大心血管变化。这些变化包括肺血流量（PBF）大幅增加，这对于肺气体交换以及替代脐静脉回流作为左心前负荷的来源是必需的。在PBF增加之前夹住脐带会减少静脉回流和左心的前负荷，从而降低心输出量。因此，如果在夹住脐带后通气开始延迟，婴儿就有因低心输出量而在窒息性损伤之上叠加缺血性损伤的风险。许多争论集中在出生时脐带结扎的时机上，主要关注胎盘向婴儿进行时间依赖性输血的可能性。这促使人们建议对不需要复苏的婴儿在出生后延迟一定时间结扎脐带。然而，最近的证据表明，在脐带结扎前开始通气可减轻立即结扎脐带所导致的不良心血管后果。这表明脐带结扎的时机应基于婴儿的生理状况而非任意的时间段，并且延迟结扎脐带可能对呼吸暂停的婴儿最为有益。
