Non-invasive measurements of ductus arteriosus flow directly after birth Jeroen J van Vonderen, 1 Arjan B te Pas, 1 Clara Kolster-Bijdevaate, 2 Jan M van Lith, 2 Nico A Blom, 3 Stuart B Hooper, 4 Arno A W Roest 3 1 Division of Neonatology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands 2 Department of Gynaecology and Obstetrics, Leiden University Medical Center, Leiden, The Netherlands 3 Division of Pediatric Cardiology, Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands 4 The Ritchie Centre, Monash Institute for Medical Research, Monash University, Clayton, Victoria, Australia Correspondence to Jeroen J van Vonderen, Department of Pediatrics, Leiden University Medical Center, J6-S, PO Box 9600, Leiden 2300 RC, The Netherlands; j.j.van_vonderen@lumc.nl Received 20 January 2014 Revised 29 April 2014 Accepted 31 May 2014 Published Online First 25 June 2014 To cite: van Vonderen JJ, te Pas AB, Kolster- Bijdevaate C, et al. Arch Dis Child Fetal Neonatal Ed 2014;99:F408–F412. ABSTRACT Objective To assess ductus arteriosus (DA) blood flow directly after birth in healthy term infants after elective caesarean section. Design In healthy term newborns, echocardiography was performed at 2, 5 and 10 min after birth to monitor cardiac output and DA blood flow. Heart rate (HR) was assessed using ECG. Setting The delivery rooms of the Leiden University Medical Center. Patients 24 healthy term infants born after a caesarean section were included in this study. Results Mean (SD) HR did not change (158 (18) beats per minute (bpm), 5 min (159 (23) bpm) and 10 min (156 (19) bpm). DA diameter decreased from 5.2 (1.3) mm at 2 min to 4.6 (1.3) mm at 5 min (p=0.01) to (3.9 (1.2) mm) (p=0.01) at 10 min. Right-to-left DA shunting was unaltered (median (IQR) 95 (64–154) mL/kg/min to 90 (56–168) mL/kg/min and 80 (64–120) mL/kg/min, respectively (ns)), whereas left-to-right shunting significantly increased between 2 and 5 min (41 (31–70) mL/kg/min vs 67 (37–102) mL/kg/min (p=0.01)) and increased significantly between 2 and 10 min (93 (67–125)) mL/kg/min (p<0.001). Right-to-left/left-to-right shunting ratio decreased significantly from 2.1 (1.4–3.1) at 2 min to 1.4 (1.0–1.8) at 5 min (p<0.0001) and to 0.9 (0.6–1.1) at 10 min (p<0.0001). Conclusions DA shunting changes swiftly from predominantly right-to-left shunting to predominantly left- to-right shunting at 10 min after birth, reflecting differential changes in pulmonary and systemic vascular resistance. INTRODUCTION Directly after birth, major changes in the respira- tory and cardiovascular systems are required for postnatal survival. 12 This includes ductus arterio- sus (DA) closure, a major vascular shunt between the pulmonary and systemic circulation. This closure is preceded by changes in the amount and direction of blood flow through the DA. DA Blood flow is determined by the pressure difference between the pulmonary artery and aorta. 3–5 Before birth, high pulmonary vascular resistance (PVR) ensures that blood flows from the right ventricle through the DA and into the systemic circulation (right-to-left (RtoL) shunting) throughout the cardiac cycle. Although blood flows into the lungs briefly during systole, during late systole and throughout diastole blood reflects off the highly resistant pulmonary vasculature and exits the pulmonary circulation across the DA. 3–6 This retro- grade pulmonary arterial flow causes high diastolic flow through DA in the fetus, as flow in the main pulmonary trunk is zero throughout much of dia- stole. 5 Approximately 90% of right ventricular output (RVO) in the fetus bypasses the lungs and flows across the DA. 3 After birth, lung aeration initiates a sudden decrease in PVR, causing the majority of RVO to enter the pulmonary circulation resulting in a large increase in pulmonary blood flow (PBF). 3 7 8 In contrast to PVR, systemic vascular resistance (SVR) increases due to cord clamping. 9 With the increase in SVR and decrease in PVR, the pressure gradient across the DA reverses and blood begins to flow from the systemic into the pulmonary circulation (left-to-right (LtoR) shunting). 6 10 11 In lambs, increase in LtoR shunt is responsible for up to 50% of PBF shortly after birth, depending on gestational age. 3 However, LtoR flow across the DA is not con- tinuous throughout the cardiac cycle, as RtoL flow occurs briefly during systole and becomes LtoR throughout most of diastole. 3 Although in ventilated lambs DA blood flow dir- ectly after birth has been described and several studies evaluated ductal flow in neonates during the first hours to days after birth, 12–17 little is known about the immediate changes in DA flow in spon- taneously breathing infants at birth. Therefore, we aimed to assess DA flow by repeated measurements using Doppler imaging in the first 10 min of life after an elective caesarean section. METHODS Healthy term infants (≥37 weeks of gestation) delivered by elective caesarean section were What is already known on this topic ▸ Ductus arteriosus flow is known to change from right to left to left to right after birth. ▸ Ductus arteriosus flow is dependent on the pressure gradient between the pulmonary and systemic circulations. What this study adds ▸ Ductus arteriosus blood flow changes already within the first 10 min to a predominantly left to right shunt in healthy infants. ▸ Ductal flow ratio reflects pulmonary and haemodynamic transition and can be used to monitor neonatal transition. F408 van Vonderen JJ, et al. Arch Dis Child Fetal Neonatal Ed 2014;99:F408–F412. doi:10.1136/archdischild-2014-306033 Original article group.bmj.com on February 11, 2015 - Published by http://fn.bmj.com/ Downloaded from