V. Houfflin-Debarge

Tracheal occlusion alters pulmonary circulation in the fetal lamb with normally developing lungs.

BACKGROUND Tracheal occlusion (TO) promotes fetal lung growth through an increase in intraluminal pressure. Although evidence suggests that fetal TO (FETO) decreases the occurrence of pulmonary hypertension in severe congenital diaphragmatic hernia, controversies on its effect on the pulmonary circulation remain. Therefore, we investigated the effects of FETO on the lung hemodynamics in a chronically catheterized fetal lamb model. METHODS Fifteen pregnant ewes were operated on between 125 and 128 days of gestation (term: 145 days). Catheters and ultrasonic flow transducer were placed through a left thoracotomy in the lamb fetus to determine aortic, pulmonary and left atrial pressures, and left pulmonary artery blood flow. A balloon was positioned between the carina and vocal cords under fetoscopic control. The animals were assigned to either control (n=6) or FETO (n=9) groups. TO was performed by inflating the balloon. We studied the acute effects of temporary (2-h) and prolonged (4-day) TO on basal pulmonary vascular tone and on the pulmonary vascular reactivity to acetylcholine and to increased fetal oxygen tension. RESULTS We found that left pulmonary blood flow (LPA) increased and pulmonary vascular resistance (PVR) decreased by 20% during brief TO (p<0.05). After balloon deflation, LPA blood flow further increased by 40%, and PVR decreased by 50% compared to baseline values (p<0.05). In contrast, no change in LPA blood flow or PVR was observed during prolonged TO. Moreover, the vasodilator responses to acetylcholine and to increased fetal PaO2 were blunted during TO. CONCLUSIONS These data indicate that antenatal tracheal occlusion promotes active pulmonary vasodilation, which is partly blunted by the mechanical effects of elevation of the intraluminal pressure.

Physiopathologie des conséquences respiratoires néonatales de la rupture prématurée des membranes : application à la prise en charge néonatale

Early premature rapture of the membranes (PROM) during pregnancy is associated with a high risk of perinatal morbidity and mortality. Early PROM impairs lung structures and function through 3 mechanisms : 1) oligo-hydramnios ; 2) fetal inflammatory syndrome ; and 3) prematurity. Thus, the related causes of respiratory failure at birth after PROM are: hyaline membrane disease, persistent pulmonary hypertension induced by impaired endothelial function and/or lung hypoplasia, materno-fetal infection, and bronchopulmonary dysplasia resulting at least in part from the fetal inflammatory syndrome. Severity of the respiratory morbidity is largely unpredictable. Even if gestational age at PROM is considered as a prognostic factor, survival without morbidity exist after PROM as early as 18 weeks GA. Better knowledge of the pathophysiology improved the outcome of the preterm infants born after early PROM. Optimal management of the respiratory failure including minimizing barotrauma is required to prevent from bronchopulmonary dysplasia.

Does an intrauterine exchange transfusion improve the fetal prognosis in parvovirus infection cases?: The fetal prognosis in parvovirus infection cases?

Almost 20% of parvovirus B19 foetal infections require intrauterine transfusions. In addition, myocardial dysfunction has been observed in severe parvovirus B19 infections. One objective of an intrauterine exchange transfusion (IUET) is to avoid an overload during the transfusion. Our aim was to study the obstetrical and neonatal outcomes in cases of IUETs performed for foetal parvovirus infections and to compare our survival rate to those studies in which simple in utero transfusions were chosen.