Hemodynamics and transplacental oxygen exchange during intact cord resuscitation in control and congenital diaphragmatic hernia lambs

Evolution of gas exchange during intact cord resuscitation (ICR) remains unexplored. We aimed to investigate changes in placental hemodynamics and gas exchange during ICR in lambs with and without congenital diaphragmatic hernia (CDH). Eight CDH lambs (4.2 kg, 4 females) and nine controls (3.9 kg, 3 females) underwent ICR. At 80 days gestation (term = 142 days), CDH was induced by diaphragmatic incision. After c-section at term, mean arterial pressure (MAP) was monitored via an aortic catheter. Umbilico-placental blood flow (Qup) was assessed with a flow transducer on the umbilical artery. Umbilical venous pressure was recorded, and blood gases from the aorta and umbilical vein were analyzed to evaluate placental oxygen transfer. ICR was performed for 60 min, followed by cord clamping (CC). Qup and umbilical venous Po₂ were similar and stable in both groups up to 50 min. MAP was 20% lower in normal lambs compared with CDH lambs (<i>P</i> < 0.05) but equalized after CC. In CDH lambs, placental oxygen transfer was maintained during ICR (2.7 [2.2-3.3] mL/kg/min). [Formula: see text] was unchanged during ICR (53 [50-58] mmHg) and abruptly increased after CC (83 [60-101] mmHg) (<i>P</i> < 0.05). For control lambs, placental oxygen transfer dropped to 0 [-0.3 to 0.2] mL/kg/min within 20 min of starting resuscitation, coinciding with an significant increase in [Formula: see text] (<i>minute 0</i> = 16 [12; 18] mmHg; <i>minute 20</i> = 50 [48-105] mmHg and <i>minute 75</i> [50; 110] mmHg after CC). ICR may support oxygenation and carbon dioxide removal in CDH newborns through placental gas exchange.<b>NEW & NOTEWORTHY</b> Maternal anesthesia with halogenated gas sustains placental circulation for 1 h postbirth. Intact cord resuscitation supports oxygenation (placental oxygen transfer ∼2.7 mL/kg/min) for 1 h in the congenital diaphragmatic hernia (CDH) lamb model. Maintaining feto-placental circulation during delivery room resuscitation in the context of CDH ensures continuous oxygenation and carbon dioxide clearance for up to 1 h.