Does antenatal glucocorticoid improve pulmonary circulatory adaptation at birth?

Abstract

ADAPTATION AT BIRTH? PHILIPPE DERUELLE, VERONIQUE DEBARGE, ERIC MAGNENANT, SOPHIE JAILLARD, THAMEUR RAKZAH, FRANCIS PUECH, LAURENT STORME, CHRU de Lille, France, Department of perinatology, Lille, France, CHU de Lille, Dept. Ob/Gyn, Lille, France OBJECTIVE: Adaptation to extra-uterine life requires dramatic modifications of pulmonary vascular resistances (PVR). Mechanisms that induce pulmonary vasodilatation at birth are incompletely understood but may include alveolar ventilation, increase of partial oxygen pressures, modifications of the shear stress and synthesis of vasoactive mediators. We hypothesized that antenatal glucocorticoids increase pulmonary vasodilatation to birth-related stimuli. To test this hypothesis, we studied pulmonary hemodynamic response at birth to ventilation in chronically prepared late-gestation fetal lamb after antenatal maternal GC injection (130-132 d of gestation). STUDY DESIGN: Catheters were inserted in the main pulmonary artery (PAP), aorta, left atrium and amniotic cavity to measure pressure. Pulmonary artery flow was measured in the left lung with an ultrasonic flow transducer. Lambs were randomized in 2 groups: ‘‘GC’’ group (dexamethasone 0.5 mg/kg) and ‘‘control’’ group (saline). 72 hours after injection, fetuses were delivered by Csection and a tracheotomy was performed. Animals were placed on a time– cycled pressure limited neonatal ventilator with a FIO2 !0.10 then a FIO2 of 1.0. Finally, the umbilical cord was ligated. PaCO2 was controlled between 35 and 45 Torr. RESULTS: Basal PVR was similar between groups. PaCO2, PaO2 and Ph were not different between groups during the study period. During ventilation with Fi02 !0.1, PVR were lower in the ‘‘GC’’ group than in ‘‘control’’ (0.18 G 0.02 vs. 0.25 G 0.01 mm Hg/mL.min, P ! .01 GC vs. control). During ventilation with 100% O2, PVR were similar between groups (0.14 G 0.02 vs. 0.15 G 0.01 mm Hg/mL.min, GC vs. control). We did not observed further decrease of the PVR after ligation between the two groups. Mean PAo and PAP did not changed during the study in both groups. CONCLUSION: Antenatal GC enhance pulmonary vasodilatation induced by alveolar ventilation but don’t modulate oxygen response. We speculate that this effect could be included to mechanisms for neo-natal hemodynamic adaptation after antenatal GC. 510 SUSPECTED FETAL MACROSOMIA: GUIDELINES VS. REALITY RONNY SHACHAR, ASNAT WALFISCH, ILANA SHOHAM-VARDI, HILLEL VARDI, MORDECHAI HALLAK, Soroka University Medical Center, Beer-Sheva, Israel OBJECTIVE: Suspected macrosomia is a common obstetric condition, which is still considered challenging. We aimed to evaluate the effect of our management policy in a suspected macrosomic fetus on pregnancy outcome. Furthermore, our prediction ability of excessive fetal weights using clinical and ultrasonographic estimations was evaluated. STUDY DESIGN: In this prospective observational study we followed the management of 145 term women who were admitted with a documented diagnosis of suspected fetal macrosomia, as well as women with fetal weight estimation of >4000 g. The diagnosis was made by an obstetrician, based on his clinical judgment and/or ultrasound results. The comparison group (n = 5943) consisted of all other women who gave birth during the data collection period. These data was received from our computerized perinatal database. RESULTS: Induction of labor and cesarean delivery rates in the macrosomic pregnancies (birth weight >4000 g) of the study group were significantly higher when compared with the macrosomic pregnancies of the comparison group (42.1% vs. 13.6%, P ! .001 and 57.1% vs. 16.7%, respectively). When comparing the non macrosomic (birth weight !4000 g) to the macrosomic pregnancies of the study group no significant difference was demonstrated regarding maternal or infant complications. The sensitivity, specificity and positive predictive value of the methods used for detecting macrosomia were 21.6%, 98.6% and 43.5% respectively. CONCLUSION: Our active management of suspected macrosomic pregnancies increased induction of labor and cesarean delivery rates without improving maternal or fetal outcome. Our ability to predict macrosomia is poor.