Effects on the maternofetal unit of the rabbit model after substitution of the amniotic fluid with perfluorocarbons.

OBJECTIVES: Exchanging amniotic fluid (AF) with perfluorocarbon (PFC) may serve as a medium for fetoscopic surgery. This study evaluates the distribution and physiologic effects of intraamniotic PFC as a medium for fetoscopy. METHODS: Fetuses of 17 pregnant rabbits underwent either exchange of the AF with PFC, electrolyte solution (ES), or control. The quality of vision during fetoscopy was assessed in AF and PFC. After 6 h, we determined the distribution of PFC in the maternofetal unit. RESULTS: Quality of vision during fetoscopy was better in PFC than with AF. There was no difference in fetal survival between the study groups. PFC was demonstrated on X-ray in the pharynx of 4 fetuses, and the esophagus in 1. CONCLUSIONS: PFC provided an ideal medium for fetoscopy without fetal compromise.

Intrapulmonary perfluorooctyl bromide instillation in fetal rabbits.

BACKGROUND: Instilling perfluorooctyl bromide (PFOB) into the fetal lung may lead to alveolar distension. OBJECTIVE: The aim of the study was to evaluate the safety of PFOB instillation into fetal lungs and to determine the radiographic distribution and tissue concentration of PFOB in New Zealand white rabbits. METHODS: Sibling fetuses of pregnant (day 27) New Zealand white rabbits were randomized to intratracheal instillation of 1 mL PFOB with tracheal ligation, instillation without ligation, and unmanipulated controls. The maternal animals were killed directly after instillation, at 3 or 6 hours (n = 10 each). For each study cohort, we determined fetal lung/body weight (FLBW) ratios, the radiographic distribution of PFOB, as well as pulmonary PFOB and water content by tissue distillation. PFOB concentrations in maternal and fetal tissues were assessed by gas chromatography. RESULTS: The relative amount of fetal lung PFOB recovered by fractional distillation was highest in ligated (25%) and lower in unligated lungs (9%). Extrapulmonary PFOB was found in the fetal brain (2.0 +/- 0.7 ppm), but not in any other fetal or maternal tissues. Mean FLBW ratios were highest in ligated fetuses, followed by unligated fetuses and controls. PFOB partially displaced fetal lung water. PFOB was visible in the lungs of all treated fetuses. Fetal survival between manipulated and unmanipulated fetuses did not differ. CONCLUSIONS: After prenatal intrapulmonary instillation, some PFOB remains in the lung, even if the trachea is not ligated, and may exert distending pressure on the alveoli.

Lung growth induced by prenatal instillation of perfluorocarbon into the fetal rabbit lung.

The study's aim was to evaluate whether prenatal instillation of perfluorooctylbromide (PFOB, a perfluorocarbon) into the lungs of fetal rabbits leads to increased lung growth. Hysteroamniotomy was performed in eight pregnant New Zealand white rabbits on gestational day 27. In each mother, four fetuses were randomized to undergo either 1) endotracheal intubation and intrapulmonary instillation of 1 ml PFOB, 2) intrapulmonary instillation of 1 ml 0.9% NaCl solution (saline), 3) no fetal manipulation (control), or 4) tracheal occlusion (TO). The distribution of PFOB was documented radiographically. The fetuses were born by cesarean section after 48 h, sacrificed, weighed, and their lungs excised. Fetal lung to body weight ratios (FLBW) were determined, and the lungs were snap frozen for histomorphologic analysis and lung tissue distillation. On macroscopic inspection, PFOB-filled and tracheally-occluded lungs were markedly larger than saline-filled and control lungs. Mean FLBW was higher in fetuses treated with intrapulmonary instillation of PFOB (0.037+/-0.009), compared with fetuses receiving saline (0.027+/-0.008) or the unmanipulated controls (0.028+/-0.008). FLBW was highest after TO (0.049+/-0.008). After 48 h, in-vivo radiographs did not demonstrate any residual PFOB. Average dry fetal left lung weight (in g) was much higher in the TO (0.064+/-0.029) and PFOB (0.062+/-0.016) fetuses compared with the saline (0.054+/-0.017) and control (0.043+/-0.012) groups. Alveolar architecture on microscopy was similar between all groups, although the alveolar septae appeared thicker and more cellular after PFOB treatment and TO. We concluded that prenatal intrapulmonary PFOB instillation leads to increased lung growth in the late gestation rabbit model. Although PFOB instillation resulted in lower wet FLBW than TO, the increase in dry lung weight is comparable. This novel technique may be a less invasive and less noxious treatment strategy for pulmonary hypoplasia associated with diaphragmatic hernia.