Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine , St. Louis, Missouri.
J Appl Physiol (1985). 2019 Jul 1;127(1):103-110. doi: 10.1152/japplphysiol.00049.2019. Epub 2019 May 2.
Delayed cord clamping (DCC) improves neurologic outcomes in preterm infants through a reduction in intraventricular hemorrhage (IVH) incidence. The mechanism behind this neuroprotective effect is not known. Infants born <28 wk gestation were recruited for longitudinal monitoring. All infants underwent 72 h of synchronized near-infrared spectroscopy (NIRS) and mean arterial blood pressure (MABP) recording within 24 h of birth. Infants with DCC were compared with control infants with immediate cord clamping (ICC), controlling for severity of illness [clinical risk index for babies (CRIB-II) score], chorioamnionitis, antenatal steroids, sedation, inotropes, and delivery mode. Autoregulatory dampening was calculated as the transfer function gain coefficient between the MABP and NIRS signals. Forty-five infants were included (DCC; = 15, paired 2:1 with ICC controls = 30). ICC and DCC groups were similar including gestational age (25.5 vs. 25.2 wk, = 0.48), birth weight (852.3 vs. 816.6 g, = 0.73), percent female (40 vs. 40%, = 0.75), and dopamine usage (27 vs. 23%, = 1.00). There was a significant difference in IVH incidence between the DCC and ICC groups (20 vs. 50%, = 0.04). Mean MABP was not different (35.9 vs. 35.1 mmHg, = 0.44). Compared with the DCC group, the ICC group had diminished autoregulatory dampening capacity (-12.96 vs. -15.06 dB, = 0.01), which remained significant when controlling for confounders. Dampening capacity was, in turn, strongly associated with decreased risk of IVH (odds ratio = 0.14, < 0.01). The results of this pilot study demonstrate that DCC is associated with improved dynamic cerebral autoregulatory function and may be the mechanism behind the decreased incidence of IVH. The neuroprotective mechanism of delayed cord clamping in premature infants is unclear. Delayed cord clamping was associated with improved cerebral autoregulatory function and a marked decrease in intraventricular hemorrhage (IVH). Improved dynamic cerebral autoregulation may decrease arterial baroreceptor sensitivity, thereby reducing the risk of IVH.
延迟结扎脐带（DCC）可通过降低脑室内出血（IVH）的发生率来改善早产儿的神经预后。这种神经保护作用的机制尚不清楚。招募胎龄<28 周的婴儿进行纵向监测。所有婴儿在出生后 24 小时内接受 72 小时同步近红外光谱（NIRS）和平均动脉血压（MABP）记录。将 DCC 婴儿与立即结扎脐带的对照婴儿（ICC）进行比较，控制疾病严重程度[婴儿临床风险指数（CRIB-II）评分]、绒毛膜羊膜炎、产前类固醇、镇静、正性肌力药和分娩方式。自动调节衰减率计算为 MABP 和 NIRS 信号之间的传递函数增益系数。共纳入 45 例婴儿（DCC 组 = 15 例，与 ICC 对照组以 2:1 配对， = 30 例）。ICC 和 DCC 组在胎龄（25.5 与 25.2 周， = 0.48）、出生体重（852.3 与 816.6 g， = 0.73）、女性比例（40%与 40%， = 0.75）和多巴胺使用率（27%与 23%， = 1.00）方面无显著差异。DCC 组与 ICC 组的 IVH 发生率存在显著差异（20%与 50%， = 0.04）。平均 MABP 无差异（35.9 与 35.1 mmHg， = 0.44）。与 DCC 组相比，ICC 组的自动调节衰减能力降低（-12.96 与-15.06 dB， = 0.01），控制混杂因素后仍有显著差异。衰减能力与 IVH 风险降低呈强烈相关（比值比=0.14， < 0.01）。这项初步研究的结果表明，DCC 与大脑动态自动调节功能的改善有关，可能是 IVH 发生率降低的原因。早产儿延迟结扎脐带的神经保护机制尚不清楚。延迟结扎脐带与大脑自动调节功能的改善和明显的脑室出血（IVH）减少有关。动态大脑自动调节功能的改善可能会降低动脉压力感受器的敏感性，从而降低 IVH 的风险。
