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.
Keywords: Neonatology; ductus arteriosus; left ventricular output; neonatal transition; right ventricular output.
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