Transition from fetal to neonatal circulation: Modeling the effect of umbilical cord clamping

Abstract

Hemodynamics of the fetal to neonatal transition are orchestrated through complex physiological changes and results in cardiovascular adaptation to the adult biventricular circulation. Clinical practice during this critical period can influence vital organ physiology for normal newborns, premature babies and congenital heart defect patients. Particularly, the timing of the cord clamping procedure, immediate (ICC) vs. delayed cord clamping (DCC), is hypothesized to be an important factor for the transitory fetal hemodynamics. The clinical need for a quantitative understanding of this physiology motivated the development of a lumped parameter model (LPM) of the fetal cardio-respiratory system covering the late-gestation to neonatal period. The LPM was validated with in vivo clinical data and then used to predict the effects of cord clamping procedures on hemodynamics and vital gases. Clinical time-dependent resistance functions to simulate the vascular changes were introduced. For DCC, placental transfusion (31.3 ml) increased neonatal blood volume by 11.7%. This increased blood volume is reflected in an increase in preload pressures by ~20% compared to ICC, which in turn increased the cardiac output (CO) by 20% (COICC=993 ml/min; CODCC=1197 ml/min). Our model accurately predicted dynamic flow patterns in vivo. DCC was shown to maintain oxygenation if the onset of pulmonary respiration was delayed or impaired. On the other hand, a significant 25% decrease in oxygen saturations was observed when applying ICC under the same physiological conditions. We conclude that DCC has a significant impact on newborn hemodynamics, mainly because of the improved blood volume and the sustained placental respiration.

Ventilation before Umbilical Cord Clamping Improves Physiological Transition at Birth or “Umbilical Cord Clamping before Ventilation is Established Destabilizes Physiological Transition at Birth”

“…He proposed that the sudden rise in cerebral circulation was the underlying mechanism for the higher incidence of intraventricular hemorrhage after early cord clamping (ECC) in preterm neonates. Our computer simulation of transitional circulation supports Hofmeyr’s finding (3). The simulation demonstrates that a sudden rise in cerebral pressure and blood flow is inevitable if the placental circulation is closed before the increase in pulmonary blood flow has occurred as a result of respiration.…”

Effects of early versus delayed umbilical cord clamping during antepartum lower segment caesarean section on placental delivery and postoperative haemorrhage: a randomised controlled trial

“…DCC improves blood pressure, reduces the need for blood transfusions and the risk of intra-ventricular haemorrhage and necrotizing enterocolitis in preterm infants [9]. Furthermore, DCC maintains oxygenation by sustained placental circulation and is beneficial if spontaneous pulmonary respiration is delayed or impaired [10][11][12][13]. Recently the use of the term 'deferred' cord clamping has been recommended as this suggests a planned policy in contrast to the term 'delayed' cord clamping which may imply that the cord is clamped later than the ideal time [14].…”

Current umbilical cord clamping practices and attitudes of obstetricians and midwives toward delayed cord clamping in Saudi Arabia

“…It has been found that a 1–3 minute DCC can significantly impact a newborn’s hemodynamics, mainly due to the improved blood volume and the sustained placental respiration. 2 …”