Ventilation Onset Prior to Umbilical Cord Clamping (Physiological-Based Cord Clamping) Improves Systemic and Cerebral Oxygenation in Preterm Lambs

Abstract

BackgroundAs measurement of arterial oxygen saturation (SpO2) is common in the delivery room, target SpO2 ranges allow clinicians to titrate oxygen therapy for preterm infants in order to achieve saturation levels similar to those seen in normal term infants in the first minutes of life. However, the influence of the onset of ventilation and the timing of cord clamping on systemic and cerebral oxygenation is not known.AimWe investigated whether the initiation of ventilation, prior to, or after umbilical cord clamping, altered systemic and cerebral oxygenation in preterm lambs.MethodsSystemic and cerebral blood-flows, pressures and peripheral SpO2 and regional cerebral tissue oxygenation (SctO2) were measured continuously in apnoeic preterm lambs (126±1 day gestation). Positive pressure ventilation was initiated either 1) prior to umbilical cord clamping, or 2) after umbilical cord clamping. Lambs were monitored intensively prior to intervention, and for 10 minutes following umbilical cord clamping.ResultsClamping the umbilical cord prior to ventilation resulted in a rapid decrease in SpO2 and SctO2, and an increase in arterial pressure, cerebral blood flow and cerebral oxygen extraction. Ventilation restored oxygenation and haemodynamics by 5–6 minutes. No such disturbances in peripheral or cerebral oxygenation and haemodynamics were observed when ventilation was initiated prior to cord clamping.ConclusionThe establishment of ventilation prior to umbilical cord clamping facilitated a smooth transition to systemic and cerebral oxygenation following birth. SpO2 nomograms may need to be re-evaluated to reflect physiological management of preterm infants in the delivery room.

European Consensus Guidelines on the Management of Respiratory Distress Syndrome – 2019 Update

“…Clamping the cord before initiation of respiration results in an acute transient reduction in left atrial filling leading to an abrupt drop in left ventricular output. Delayed “physiological” clamping after lung aeration results in much smoother transition and less bradycardia in animal models [36]. The Australian Placental Transfusion Study randomised 1,600 babies less than 30 weeks’ gestation to immediate (within 10 s) or delayed clamping (after 60 s or more) [37].…”

The Changing Landscape in Supporting Preterm Infants at Birth

“…While the benefit of DCC has been attributed to placental transfusion, it is now apparent that there is a much larger potential benefit if cord clamping is delayed until after the lung has aerated. This approach is called physiological-based cord clamping (PBCC) and leads to a more stable hemodynamic transition as preload and cardiac output is sustained and the large disturbances in systemic and cerebral hemodynamics during transition are avoided [5, 10, 32, 33]. …”

“…Recent experimental studies in preterm lambs demonstrated that clamping the cord after lung aeration prevents the reduction in cardiac output, cerebral perfusion, and cerebral and SpO 2 associated with cord clamping, and as such, less oxygen was needed [10]. The key factor here is the increase in pulmonary blood flow (PBF) that is triggered by lung aeration.…”

“…The first finding relates to how the larynx functions at birth, providing the realization that it can hinder noninvasively applied ventilation in preterm infants [8, 9]. The second is the increasing awareness that the timing of cord clamping has a major influence on the physiological changes during transition [5, 10]. …”

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].…”