Arch Dis Child Fetal Neonatal Ed. 2019 Feb 6. pii: fetalneonatal-2018-316045. doi: 10.1136/archdischild-2018-316045. [Epub ahead of print]
Neonatal cardiopulmonary transition in an ovine model of congenital diaphragmatic hernia.
Kashyap AJ1,2, Crossley KJ1,2, DeKoninck PLJ1,3, Rodgers KA1,2, Thio M4,5, Skinner SM1,2, Deprest JA6,7, Hooper SB1,2, Hodges RJ1,8.
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Infants with a congenital diaphragmatic hernia (CDH) are at high risk of developing pulmonary hypertension after birth, but little is known of their physiological transition at birth. We aimed to characterise the changes in cardiopulmonary physiology during the neonatal transition in an ovine model of CDH.

A diaphragmatic hernia (DH) was surgically created at 80 days of gestational age (dGA) in 10 fetuses, whereas controls underwent sham surgery (n=6). At 138 dGA, lambs were delivered via caesarean section and ventilated for 2 hours. Physiological and ventilation parameters were continuously recorded, and arterial blood gas values were measured.

DH lambs had lower wet lung-to-body-weight ratio (0.0160.002vs0.0330.004), reduced dynamic lung compliance (0.40.1mL/cmH2O vs1.20.1 mL/cmH2O) and reduced arterial pH (7.110.05vs7.260.05), compared with controls. While measured pulmonary blood flow (PBF) was lower in DH lambs, after correction for lung weight, PBF was not different between groups (4.050.60mL/min/gvs4.290.57 mL/min/g). Cerebral tissue oxygen saturation was lower in DH compared with control lambs (55.73.5vs67.7%3.9%).

Immediately after birth, DH lambs have small, non-compliant lungs, respiratory acidosis and poor cerebral oxygenation that reflects the clinical phenotype of human CDH. PBF (indexed to lung weight) was similar in DH and control lambs, suggesting that the reduction in PBF associated with CDH is proportional to the degree of lung hypoplasia during the neonatal cardiopulmonary transition.

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