Delayed cord clamping is associated with improved dynamic cerebral autoregulation and decreased incidence of intraventricular hemorrhage in preterm infants

Abstract

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; n = 15, paired 2:1 with ICC controls n = 30). ICC and DCC groups were similar including gestational age (25.5 vs. 25.2 wk, P = 0.48), birth weight (852.3 vs. 816.6 g, P = 0.73), percent female (40 vs. 40%, P = 0.75), and dopamine usage (27 vs. 23%, P = 1.00). There was a significant difference in IVH incidence between the DCC and ICC groups (20 vs. 50%, P = 0.04). Mean MABP was not different (35.9 vs. 35.1 mmHg, P = 0.44). Compared with the DCC group, the ICC group had diminished autoregulatory dampening capacity (-12.96 vs. -15.06 dB, P = 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, P < 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. NEW & NOTEWORTHY 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.

Keywords: autoregulation; blood pressure; delayed cord clamping; near-infrared spectroscopy; prematurity.

Fig. 1.

Plots are shown for data derived from a single exemplar patient. Top left: the error corrected near-infrared spectroscopy (NIRS) and mean arterial blood pressure (MABP) signals. Top middle: the spectral power of the MABP and NIRS signals (note: y-axis is logarithmic). Top right: an estimate of the transfer function gain coefficient over time (in 20-min intervals). Bottom: ensemble average of gain (left), phase (middle), and coherence (right) by frequency.

Fig. 2.

Top left: group average plots gain by cord clamping type. Top right: phase by cord clamping type. Bottom: coherence by cord clamping type. For the gain coefficient, the shaded areas the 95% confidence interval. ICC, immediate cord clamping; DCC, delayed cord clamping.

Fig. 3.

Box plot of the gain coefficients for the immediate cord clamping (ICC) and delayed cord clamping (DCC) groups. The dark bar represents median values, and box limits represent interquartile range and whiskers represent extremes. Open circles are outliers.

Fig. 4.

Plots of the gain coefficient by frequency for infants with and without intraventricular hemorrhage (IVH). Shaded areas represent the 95% confidence interval.

Fig. 5.

Spectral power density by group for near-infrared spectroscopy (NIRS) and mean arterial blood pressure (MABP) signals. Shaded areas represent ± 1 SE. Note no difference in MABP power and somewhat less power in the delayed cord clamping (DCC) NIRS power. ICC, immediate cord clamping.