Abstract
Spontaneous breathing at birth influences ductus arteriosus (DA) flow. This study quantifies the effect of breathing on DA shunting directly after birth. In healthy term infants born by elective cesarean section, simultaneous measurements of DA shunting and tidal volumes during spontaneous breathing were performed at 2–5, 5–8, and 10–13 min after birth. Eight infants with a mean (SD) gestational age of 40 (1) weeks and 3216 (616) grams were studied. Inspiratory tidal volume was 5.8 (3.3–7.7), 5.7 (4.0–7.1), and 5.2 (4.3–6.1) mL/kg at 2–5, 5–8, and 10–13 min. The velocity time integral of left-to-right shunting significantly increased during inspiration when compared to expiration (8.4 (5.2) vs. 3.7 (2.3) cm, 8.9 (4.4) vs. 5.6 (3.4) cm, and 14.0 (6.7) vs. 8.4 (6.9) cm; all p < 0.0001) at 2–5, 5–8, and 10–13 min, respectively. In contrast, right-to-left shunting was not different between inspiration and expiration at 2–5 and 10–13 min (11.1 (2.4) vs. 11.1 (2.6) cm and 10.7 (2.3) vs. 10.6 (3.0) cm; p > 0.05), but there was a small increase at 5–8 min (12.1 (2.4) vs. 10.8 (2.9) cm; p = 0.001) during expiration.Conclusion: Directly after birth, ductal shunting is influenced by breathing effort, predominantly with an increase in left-to-right shunt due to inspiration.What is Known:• Spontaneous breathing at birth influences ductus arteriosus flow and pulmonary blood flow.• Crying causes a significant increase in left-to-right ductus arteriosus shunting.What is New:• Left-to-right ductus arteriosus shunting increases during inspiration compared to expiration.• Breathing is important for ductal shunting and contributes to pulmonary blood flow.
Highlights
After birth, lung aeration has a large impact on the changes that take place in both the hemodynamic and respiratory systems [6, 9]
Crying causes a significant increase in left-to-right ductus arteriosus shunting
Breathing is important for ductal shunting and contributes to pulmonary blood flow
Summary
Lung aeration has a large impact on the changes that take place in both the hemodynamic and respiratory systems [6, 9]. Lung aeration causes a decrease in pulmonary vascular resistance (PVR) and an increase of pulmonary blood flow (PBF), of which in lambs 30–50% originates from left-to-right (LtoR) shunting through the ductus arteriosus (DA) [1]. We recently observed that in infants, in the first 10 min after birth, DA shunting changes from predominantly right-to-left (RtoL) to predominantly LtoR [10]. We observed that the large sub atmospheric pressures during the inspiratory phase of crying significantly increased LtoR shunting, most probably because it causes large decreases in transpulmonary pressure [11]. We aimed to quantify the change in DA shunt flow and its relationship with the inspiratory and expiratory phases of the respiratory cycle during spontaneous breathing in term infants directly after birth
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