Lung To Body Weight Ratio Research Articles

The metabolic and lipidomic profiling of the effects of tracheal occlusion in a rabbit model of congenital diaphragmatic hernia

PurposeFetal tracheal occlusion (TO) reverses the pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH), but its mechanism of action remains poorly understood. ‘Omic’ readouts capture metabolic and lipid processing function, which aid in understanding CDH and TO metabolic mechanisms. MethodsCDH was created in fetal rabbits at 23 days, TO at 28 days and lung collection at 31 days (Term ∼32 days). Lung-body weight ratio (LBWR) and mean terminal bronchiole density (MTBD) were determined. In a cohort, left and right lungs were collected, weighed, and samples homogenized, and extracts collected for non-targeted metabolomic and lipidomic profiling via LC–MS and LC–MS/MS, respectively. ResultsLBWR was significantly lower in CDH while CDH + TO was similar to controls (p = 0.003). MTBD was significantly higher in CDH fetuses and restored to control and sham levels in CDH + TO (p < 0.001). CDH and CDH + TO resulted in significant differences in metabolome and lipidome profiles compared to sham controls. A significant number of altered metabolites and lipids between the controls and CDH groups and the CDH and CDH + TO fetuses were identified. Significant changes in the ubiquinone and other terpenoid-quinone biosynthesis pathway and the tyrosine metabolism pathway were observed in CDH + TO. ConclusionCDH + TO reverses pulmonary hypoplasia in the CDH rabbit, in association with a specific metabolic and lipid signature. A synergistic untargeted ‘omics’ approach provides a global signature for CDH and CDH + TO, highlighting cellular mechanisms among lipids and other metabolites, enabling comprehensive network analysis to identify critical metabolic drivers in disease pathology and recovery. Type of StudyBasic Science, Prospective. Level of EvidenceII.

Safety and efficacy of smart tracheal occlusion device in diaphragmatic hernia lamb model.

To investigate the efficacy and safety of the 'smart' tracheal occlusion (Smart-TO) device in fetal lambs with diaphragmatic hernia (DH). DH was created in fetal lambs on gestational day 70 (term, 145 days). Fetuses were allocated to either pregnancy continuation until term (DH group) or fetoscopic endoluminal tracheal occlusion (TO), performed using the Smart-TO balloon on gestational day 97 (DH + TO group). On gestational day 116, the presence of the balloon was confirmed on ultrasound, then the ewe was walked around a 3.0-Tesla magnetic resonance scanner for balloon deflation, which was confirmed by ultrasound immediately afterwards. At term, euthanasia was performed and the fetus retrieved. Efficacy of occlusion was assessed by the lung-to-body-weight ratio (LBWR) and lung morphometry. Safety parameters included tracheal side effects assessed by morphometry and balloon location after deflation. The unoccluded DH lambs served as a comparator. Six fetuses were included in the DH group and seven in the DH + TO group. All balloons deflated successfully and were expelled spontaneously from the airways. In the DH + TO group, in comparison to controls, the LBWR at birth was significantly higher (1.90 (interquartile range (IQR), 1.43-2.55) vs 1.07 (IQR, 0.93-1.46); P = 0.005), while on lung morphometry, the alveolar size was significantly increased (mean linear intercept, 47.5 (IQR, 45.6-48.1) vs 41.9 (IQR, 38.8-46.1) μm; P = 0.03); whereas airway complexity was lower (mean terminal bronchiolar density, 1.56 (IQR, 1.0-1.81) vs 2.23 (IQR, 2.14-2.40) br/mm2 ; P = 0.005). Tracheal changes on histology were minimal in both groups, but more noticeable in fetal lambs that underwent TO than in unoccluded lambs (tracheal score, 2 (IQR, 1-3) vs 0 (0-1); P = 0.03). In fetal lambs with DH, TO using the Smart-TO balloon is effective and safe. Occlusion can be reversed non-invasively and the deflated intact balloon expelled spontaneously from the fetal upper airways. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

New device permitting non-invasive reversal of fetal endoscopic tracheal occlusion: ex-vivo and in-vivo study.

One of the drawbacks of fetal endoscopic tracheal occlusion (FETO) for congenital diaphragmatic hernia is the need for a second invasive intervention to re-establish airway patency. The 'Smart-TO' device is a new balloon for FETO that deflates spontaneously when placed in a strong magnetic field, therefore overcoming the need for a second procedure. The safety and efficacy of this device have not yet been demonstrated. The aim of this study was to investigate the reversibility, local side effects and occlusiveness of the Smart-TO balloon, both in a simulated in-utero environment and in the fetal lamb model. First, the reversibility of tracheal occlusion by the Smart-TO balloon was tested in a high-fidelity simulator. Following videoscopic tracheoscopic balloon insertion, the fetal mannequin was placed within a 1-L water-filled balloon to mimic the amniotic cavity. This was held by an operator in front of their abdomen, and different fetal and maternal positions were simulated to mimic the most common clinical scenarios. Following exposure to the magnetic field generated by a 1.5-T magnetic resonance (MR) machine, deflation of the Smart-TO balloon was assessed by tracheoscopy. In cases of failed deflation, the mannequin was reinserted into a water-filled balloon for additional MR exposure, up to a maximum of three times. Secondly, reversibility, occlusiveness and local effects of the Smart-TO balloon were tested in vivo in fetal lambs. Tracheal occlusion was performed in fetal lambs on gestational day 95 (term, 145 days), either using the balloon currently used in clinical practice (Goldbal2) (n = 5) or the Smart-TO balloon (n = 5). On gestational day 116, the presence of the balloon was assessed by tracheoscopy. Deflation was performed by puncture (Goldbal2) or MR exposure (Smart-TO). Six unoccluded fetal lambs served as controls. Following euthanasia, the lung-to-body-weight ratio (LBWR), lung morphometry and tracheal circumference were assessed. Local tracheal changes were measured using a hierarchical histologic scoring system. Ex vivo, Smart-TO balloon deflation occurred after a single MR exposure in 100% of cases in a maternal standing position with the mannequin at a height of 95 cm (n = 32), 55 cm (n = 8) or 125 cm (n = 8), as well as when the maternal position was 'lying on a stretcher' (n = 8). Three out of eight (37.5%) balloons failed to deflate at first exposure when the maternal position was 'sitting in a wheelchair'. Of these, two balloons deflated after a second MR exposure, but one balloon remained inflated after a third exposure. In vivo, all Smart-TO balloons deflated successfully. The LBWR in fetal lambs with tracheal occlusion by a Smart-TO balloon was significantly higher than that in unoccluded controls, and was comparable with that in the Goldbal2 group. There were no differences in lung morphometry and tracheal circumference between the two balloon types. Tracheal histology showed minimal changes for both balloons. In a simulated in-utero environment, the Smart-TO balloon was effectively deflated by exposure of the fetus in different positions to the magnetic field of a 1.5-T MR system. There was only one failure, which occurred when the mother was sitting in a wheelchair. In healthy fetal lambs, the Smart-TO balloon is as occlusive as the clinical standard Goldbal2 system and has only limited local side effects. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

581: Safety and efficacy of the Smart tracheal occlusion balloon for congenital diaphragmatic hernia

To investigate the operation, safety and efficacy of the Smart-TO balloon (Strasbourg University-BSMTI, France) for fetoscopic endoluminal tracheal occlusion (FETO), which spontaneously deflates when placed in a strong magnetic field. We assessed deflation of the Smart-TO by first performing tracheal occlusion (TO) in a high-fidelity simulator. Thereafter the mannequin was placed inside a water-filled balloon mimicking the uterus and held in different positions (Figure 1). Following exposure to the magnetic field generated by a 1.5 T MRI machine, deflation was assessed fetoscopically. If not deflated, an additional exposure with maximum of three was attempted. Occlusiveness, tracheal side effects and deflation were tested in vivo in fetal lambs. FETO was performed on gestational day 95 (GD; term=145) either with the standard Goldbal2 (n=5) or Smart-TO balloon (n=5). On GD116 the presence of the balloon was assessed by tracheoscopy. Deflation was performed by puncture (Goldbal2) or by MR-exposure (Smart-TO). Following euthanasia the lung-to-body-weight-ratio (LBWR), lung morphometry, tracheal circumference at the level of the plug were assessed and tracheal changes were measured using a validated histologic scoring system. Six unoccluded lambs served as controls. Balloon deflation occurred in 100% of when standing (N=48) and when laying on a stretcher (N=8). When sitting in a wheelchair, three balloons failed to deflate (37.5%) on first exposure, one eventually did neither after third exposure (12.5%) (Figure 1). In vivo, all Smart-TO balloons deflated successfully. The LBWR was above the normal and comparable for both balloon types (Figure 2). There were no differences in lung morphometry, tracheal circumference and tracheal histology showed minimal changes for both balloons (Figure 2). Smart-TO balloon deflation can be achieved irrespective of the fetal position, both standing and laying on a stretcher. Sitting on a wheelchair may affect deflation. In healthy lambs the Smart-TO seems to minimal side effects on the trachea and increases lung weight.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

The effects of tracheal occlusion on Wnt signaling in a rabbit model of congenital diaphragmatic hernia

PurposeTracheal occlusion (TO) reverses pulmonary hypoplasia (PH) in congenital diaphragmatic hernia (CDH), but its mechanism of action remains poorly understood. Wnt signaling plays a critical role in lung development, but few studies exist. The purpose of our study was to a) confirm that our CDH rabbit model produced PH which was reversed by TO and b) determine the effects of CDH +/− TO on Wnt signaling. MethodsCDH was created in fetal rabbits at 23 days, TO at 28 days, and lung collection at 31 days. Lung body weight ratio (LBWR) and mean terminal bronchiole density (MTBD) were determined. mRNA and miRNA expression was determined in the left lower lobe using RT-qPCR. ResultsFifteen CDH, 15 CDH + TO, 6 sham CDH, and 15 controls survived and were included in the study. LBWR was low in CDH, while CDH + TO was similar to controls (p = 0.003). MTBD was higher in CDH fetuses and restored to control levels in CDH + TO (p < 0.001). Reference genes TOP1, SDHA, and ACTB were consistently expressed within and between treatment groups. miR-33 and MKI67 were increased, and Lgl1 was decreased in CDH + TO. ConclusionTO reversed pulmonary hypoplasia and stimulated early Wnt signaling in CDH fetal rabbits. Type of studyBasic science, prospective. Level of evidenceII.

Protective effect of baicalin on fetal lung development in a rabbit model of congenital diaphragmatic hernia.

Bacalin has been reported to improve fetal lung growth by increasing fetal lung surfactant phospholipids. Therefore, the present study evaluated the effect of transplacental treatment of baicalin during lung development in rabbits with congenital diaphragmatic hernia (DH) rabbit. DH was induced in fetal rabbit on gestational day 23 and baicalin injections were administered daily until term period. Fetal survival rate, body weight and lung-to-body weight ratio (LBWR) were subsequently measured, and the expression of surfactant protein B (SPB) and Ki-67, and morphometry analysis was determined in lung tissues. It was observed that in baicalin treated group the fetal survival rate and LBWR were decreased compared with the control without DH group. Lung morphometry results suggested that treatment with baicalin did not significantly ameliorate congenital DH, and adventitial and medial thickness were similar to those in the control groups, and less muscularization of vessels measuring 30–60 µm. Furthermore, baicalin treatment did not markedly affect the expressions of Ki-67 and SPB in fetuses with DH. Baicalin was demonstrated to improve the morphology of lung in rabbits; however, as it did not induce marked airway changes this present study suggests that baicalin is not suitable for the management of congenital DH.

The Effect of Transplacental Administration of Glucagon-Like Peptide-1 on Fetal Lung Development in the Rabbit Model of Congenital Diaphragmatic Hernia

Objective: Glucagon-like peptide-1 (GLP-1) increases surfactant protein expression in type 2 pneumocytes. Herein, we determine if transplacental GLP-1 treatment accelerates lung growth in the fetal rabbit model of congenital diaphragmatic hernia (DH). Methods: Time-mated does had an induction of DH on day 23 followed by daily GLP-1 or placebo injection until term. At that time, the does were weighed, fetal blood was obtained for GLP-1 assay, and the lungs were dissected. Fetal outcome measures were lung-to-body-weight ratio (LBWR), morphometry, and Ki67 and surfactant protein B (SPB) expression. Results: Maternal weight loss in the GLP-1 group was 7.1%. Fetal survival was lower in GLP-1 fetuses compared to placebo controls (27/85, 32% vs. 35/57, 61%; p < 0.05). Fetal GLP-1 levels were increased 3.6-fold. The LBWR of GLP-1 DH fetuses fell within the range of DH placebo fetuses (1.166 ± 0.207% vs. 1.312 ± 0.418%), being significantly lower than that of placebo-exposed unoperated fetuses (2.280 ± 0.522%; p < 0.001). GLP-1 did not improve airway morphometry. GLP-1 DH lungs had a reduced adventitial and medial thickness within the range of controls, and lesser muscularization of vessels measuring 30-60 µm. There were no differences in Ki67 and SPB expression. Conclusion: GLP-1 at this dosage improves peripheric pulmonary vessel morphology in intra-acinar vessels with no effect on airway morphometry but with significant maternal and fetal side effects. Thus, it is an unlikely medical strategy.

Medical interventions to reverse pulmonary hypoplasia in the animal model of congenital diaphragmatic hernia: A systematic review.

We aimed to systematically review all published pre-clinical research on prenatal medical treatment of pulmonary hypoplasia in congenital diaphragmatic hernia (CDH). Background The neonatal mortality due to isolated CDH remains high. Whether fetal endoscopic tracheal occlusion (FETO) reduces mortality is still to be demonstrated. Therefore more potent preferentially medical therapy would be welcomed. Methods We searched MEDLINE (Pubmed), Embase and the Web of Science including all studies from the earliest date (1951) to December 2013. Article quality was assessed using the modified CAMRADES checklist. Inclusion criteria were those animal studies addressing prenatal medical interventions and principal variables were confirmation of a diaphragmatic defect, lung to body weight ratio (LBWR), formal airway morphometry or DNA/protein content. Results In total 983 articles were identified. Following abstract review, 96 articles were assessed by two authors in agreement with a third for eligibility. Of these, 43 were included in the final analysis. The median number of study quality checklist items (maximum 10) scored was 4 (IQ range: 2-5). Thirty (69.8%) of studies were in the nitrofen rat. The majority were treated with vitamins or glucocorticoids. Single studies reported some improvement in lung morphology with alternative therapies. It was impossible to identify a pattern in animal model selection or creation, mode, time point or duration of treatment and readouts. Only one study reported a sample size calculation. Conclusion Comparison in pre-clinical studies in CDH is challenging due to methodological variation. Agreed standardized methods need to be applied in future investigation of new medical therapies.

Experimental Evaluation of Tracheo-Amniotic Shunting for Induced Congenital High Airway Obstruction in a Sheep Model

Objective: To evaluate the feasibility of tracheo-amniotic shunting in a sheep model for congenital high airway obstruction syndrome. Material and Methods: High airway obstruction was induced around day 95 (term = 145 days) in 10 lamb fetuses by tracheal clipping. Five days later, ultrasound-guided tracheoamniotic shunting was done using either the Harrison double-pigtail bladder stent (HS) or a double-basket device (BS). Caesarean section (CS) was done around day 110. At each time point, the cardiothoracic index (CTI) was measured. Lung-to-body weight ratio (LBWR) was calculated at fetal necropsy. The primary endpoint was successful shunting defined as anatomically correct placement and functional airway decompression; the secondary endpoint was survival until CS. Results: Two sheep aborted 3 fetuses after tracheal occlusion. Overall, the median CTI at CS was significantly smaller compared to baseline [0.52 (interquartile range, IQR: 0.52-0.54) vs. 0.58 (IQR: 0.54-0.63); p = 0.01]. In the HS group (n = 4), none of the shunts were correctly positioned. In the BS group (n = 3), there was 1 correct shunt placement; however, this fetus was stillborn. Median LBWR suggested pulmonary overgrowth [0.10 (IQR: 0.08-0.11)]. Conclusion: In our hands, using this model with a long and mobile neck and relative oligohydramnios, tracheoamniotic shunting for airway obstruction has a high failure rate. If further pursued, alternative techniques or different models should be considered.

S138 Nanodiamond Delivery Of Vascular Endothelial Growth Factor Promotes Fetal Lung Development In A Rat Model Of Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is a developmental diaphragmatic anomaly resulting in pulmonary hypoplasia and consequent pulmonary hypertension and respiratory failure sequelae. Despite advances in treatment, CDH remains associated with high morbidity and mortality rates. Reduced levels of vascular endothelial growth factor (VEGF) have been implicated in CDH pathogenesis. Animal studies have shown that intrauterine VEGF replacement enhances pulmonary vascularisation and lung epithelial cell proliferation. This study aimed to deliver VEGF through the engineering of a biocompatible and slow releasing nanodiamond (ND) platform, in a rat model of CDH. NDs were either fluorescently labelled (ND-FL) or conjugated to recombinant VEGF164 (ND-VEGF; 2 μg/mL VEGF164). Nitrofen was administered to pregnant Wistar rats at E9 (term=E22) to induce fetal CDH. At E19, maternal hysterotomy was performed, and NDs (75 μg/mL in 50 μL vehicle/saline) were administered intratracheally followed by fetal tracheal occlusion (TO). Blinded assessment of lung-to-body weight ratio (LBWR) and lung morphometric parameters was performed at E21.5 in CDH offspring. Prenatal ND administration did not have overt adverse effects. ND-FL biodistribution indicated that NDs localised in type II pneumocytes. ND-VEGF+TO was associated with improved lung growth (LBWR: 5.9 ± 0.2%), which was greater than that observed in VEGF+TO (3.5 ± 0.4%; p This is the first study to show that nanoparticle-mediated prenatal delivery of VEGF induces significant lung growth in CDH and suggests that sustained cargo release is pivotal in mimicking the temporal expression of VEGF in normal lung development.

234 Effectiveness of Fetal Perflurocarbon Therapy for Lung Hypoplasia in Diaphragmatic Hernia

AimsTo assess the effects of fetal, intratracheal perfluoroctylbromid (PFOB) instillation on lung-mechanics and gene expression of Surfactant and developmental proteins in a newborn rabbit model of lung hypoplasia.MethodsOn day 23/31,...

Prediction of pulmonary hypoplasia in mid‐trimester preterm prelabor rupture of membranes: research or clinical practice?

Prediction of pulmonary hypoplasia in mid‐trimester preterm prelabor rupture of membranes: research or clinical practice?

Antenatal ultrasound prediction of pulmonary hypoplasia in congenital diaphragmatic hernia: correlation with pathology

To examine the relationship between observed to expected (o/e) lung to head circumference ratio (LHR) and lung-to-body weight ratio (LBWR) in fetuses with congenital diaphragmatic hernia (CDH). All consecutive fetuses with CDH and termination of pregnancy for which a postmortem examination was available, examined at three institutions between 2000 and 2010, were included in the study. Contralateral fetal lung area was measured by two-dimensional ultrasonography using the longest axis method and the o/e-LHR was calculated based on the appropriate normal mean for gestational age (GA). Regression analysis was used to determine the significance of association between the LBWR and the o/e-LHR for left and right-sided cases, and subsequently the predicted LBWR in left-sided CDH was calculated using the regression equation. Regression analysis was used to investigate the effect on the proportional difference between the predicted and observed LBWR of GA at o/e-LHR, time gap between o/e-LHR and LBWR measurement, proportional weight of the ipsilateral compared with total lung weight, presence of associated anomalies and intrathoracic herniation of the liver. There were 23 fetuses with left-sided and seven fetuses with right-sided CDH. In left-sided CDH, the LBWR and the o/e-LHR correlated significantly, following the linear equation: LBWR = 0.0043 + (0.0134 × o/e-LHR) (r = 0.52, P = 0.012), but this was not the case for right-sided CDH, for which LBWR followed the equation: LBWR = 0.0107 - (0.0014 × o/e-LHR) (r = 0.08, P = 0.862), where o/e-LHR is expressed as percentage. Regression analysis showed that the proportional difference between predicted and observed LBWR in left-sided CDH was significantly and independently associated with GA at o/e-LHR measurement and proportional weight of ipsilateral vs. total lung weight. In left-sided CDH, o/e-LHR correlates well with LBWR irrespective of the length of time between o/e-LHR and LBWR measurement, presence of associated anomalies and intrathoracic herniation of the liver. Inconsistencies between the two measurements are mainly attributable to the contribution of the ipsilateral lung to the total lung weight. In right-sided CDH, o/e-LHR does not correlate with LBWR.

Morphologic changes and methodological issues in the rabbit experimental model for diaphragmatic hernia.

Fetal lung development may be impaired by some congenital anomalies or in utero events. Animal models are used to understand the pathophysiology of these diseases and explore therapeutic strategies. Our group has an interest in the prenatal management of congenital diaphragmatic hernia (CDH). Isolated CDH remains associated with a 30% mortality because of lung hypoplasia and pulmonary hypertension. On day 23 of gestation (pseudoglandular stage) CDH was created in both ovarian-end fetuses (n= 28) in 14 time-mated pregnant white rabbits (hybrid of Dendermonde and New-Zealand White). At term (day 30) all survived operated fetuses and size-matched controls were harvested. Fetuses/lungs were assigned randomly to formalin fixation either under pressure of 25 cm H2O (CDH25 n=5; CTR25 n=5) or without (0 cm H2O (CDH0 n=7; CTR0 n=7). Fetuses and lungs were first weighed, and then the lungs were processed for morphometry. Pulmonary development was evaluated by lung-to-body weight ratio (LBWR) and airway and vascular morphometry. Surgical induction of CDH does reduce the LBWR to hypoplastic levels. The contralateral lung weight is 81% of what is expected, whereas the ipsilateral lung is only 46% of the normal. This was accompagnied by a loss of conducting airway generations, precisely, terminal bronchioles (TB), which were surrounded by less alveoli. The ipsilateral CDH lung demonstrated a thickened media in the peripheral arteries as well. As a result, in the severely hypoplastic ipsilateral lung, an airway fixation pressure of 25 H2O has no significant effect on the morphometric indices. The contralateral lung has a normal amount of alveoli around a single TB, which also behave like alveoli of the normal lung, i.e. expand under pressure fixation. The present study on severely hypoplastic lungs that never respirated, shows that in contrast to normal lungs, the morphometric indices are not significantly influenced by a difference in fixation pressure. Increasing fixation pressure seems to expand the lung only when sufficient alveolated parenchyma is present.

Albumin as an adjunct to tracheal occlusion in fetal rats with congenital diaphragmatic hernia: a placebo-controlled study

We sought to investigate effects of intratracheal albumin injection prior to tracheal occlusion (TO) on lung proliferation in fetal rats with nitrofen-induced congenital diaphragmatic hernia. On embryonic day 19, nitrofen-exposed fetuses underwent TO, TO and 50 microL of either intratracheal albumin 20% or saline, or remained untouched. Main outcome at embryonic day 21.5 was expression of the proliferation marker Ki-67. Secondary outcomes were lung-to-bodyweight ratio (LBWR), tropoelastin expression, density and spatial distribution of elastin, pulmonary/alveolar morphometry, and fetal survival. TO increased Ki-67 messenger RNA and LBWR. Albumin further increased LBWR and density of Ki-67-positive cells but also fetal mortality. TO with or without adjuncts induced elastin deposits at the tips of arising secondary crests, increased air space size, and decreased septal thickness. TO had effects on lung proliferation and advanced the morphologic appearance. Addition of albumin increased density of proliferating cells and LBWR, yet at the expense of additional fetal loss.

OC24.04: Echocardiographic predictors of acute recipient twin demise following selective fetoscopic laser photocoagulation for twin-twin transfusion syndrome

Results: Eleven CDH fetuses, 9 CDH+TO and 20 controls were suitable for the study. CDH fetuses showed significantly higher PI (8.0 (SD 1.8) vs. 5.22 (SD 1.1) p<0.001) and lower FMBV (13.5% (SD 4.6) vs. 23.0% (SD 2.1) p<0.001) than controls. In contrast, CDH-TO fetuses had significantly lower PI (5.8 (SD 2.3) vs. 8.0 (SD 1.8) p=0.015) and higher FMBV (27.6% (SD 7.1) vs. 13.5% (SD 4.6) p<0.001) than CDH fetuses, with values similar to controls. PEDRF and PSV showed non significant differences among the study groups. The lung to body weight ratio (LBWR) at necropsy correlated positively with lung FMBV (r=0.60 p<0.001) and negatively with pulmonary artery PI (r= −0.48 p<0.01). Conclusion: Tracheal occlusion is consistently associated with increased lung tissue perfusion and decreased intrapulmonary impedance in a rabbit model of CDH.

The effect of maternal betamethasone and fetal tracheal occlusion on pulmonary vascular morphometry in fetal rabbits with surgically induced diaphragmatic hernia: a placebo controlled morphologic study

We studied the vascular effects of betamethasone (BM) and/or tracheal occlusion (TO) in fetal rabbits with surgically induced congenital diaphragmatic hernia (CDH). At day 23 (pseudoglandular phase; term = 31 d), 54 ovarian-end fetuses from 27 does underwent induction of CDH. Thirteen did receive either 0.05 mg/kg BM, on days 28 and 29 with a 24-h interval, or 14 saline [controls (CTR)]. At day 28, one ovarian-end fetus underwent TO and harvesting was at term. In total, we compared (ANOVA) lung-to-body weight ratio (LBWR) and vascular morphometric indices in survivors from the following groups (n - number alive at delivery): CDH (9); CDH + TO (10); unoperated controls (14); CDH + BM (10); CDH + TO (9); controls CTR + BM (13). Maternal BM had no effect on LBWR. LBWR was comparable to normal in CDH fetuses undergoing TO. Both TO and BM have an effect on medial thickening due to CDH which is larger when both interventions are combined. Both TO and BM lessen peripheric muscularization present in CDH lungs and their effect is cumulative.

The effect of fetal tracheal occlusion on lung tissue mechanics and tissue composition

Fetal tracheal occlusion (TO) is currently used to treat severe cases of congenital diaphragmatic hernia (DH). Clinical and experimental studies suggest an improved postnatal outcome, but lung tissue mechanics after TO have not been studied. We determined the effect of TO on mechanical impedance and lung tissue components in a rabbit model for DH. At 23 days of gestation (term = 31 days) either a sham thoracotomy or a diaphragmatic defect was induced. DH fetuses were randomly assigned to undergo 5 days later TO. Fetuses were delivered by term cesarean section to determine lung to body weight ratio (LBWR), dynamic lung mechanics and lung impedance. Airway resistance (R(aw)), elastance (H(L)), tissue damping (G(L)) and hysteresivity (G(L)/H(L)) were calculated from impedance data. Collagen I and III and elastin were quantified histologically. LBWR was significantly increased by TO compared to DH (P < 0.001) and resistance and compliance of the respiratory system (R(rs), C(rs)) were improved as well. TO resulted in a significant decrease of R(aw) comparable to observations in sham-fetuses, without effect on lung tissue mechanics H(L), G(L) and hysteresivity. This coincides with a significant decrease of collagen I, III and elastin in comparison to DH fetuses. In this first report on lung tissue mechanics in a rabbit model of DH, TO had a substantial effect on tissue morphology yet this was not mirrored in lung mechanics. We conclude that the effect of TO on lung mechanics without in utero reversal of occlusion, is dominated by airway remodeling.

Maternal administration of betamethasone inhibits proliferation induced by fetal tracheal occlusion in the nitrofen rat model for congenital diaphragmatic hernia: a placebo-controlled study

Fetal tracheal occlusion (TO) is offered to fetuses with severe pulmonary hypoplasia due to congenital diaphragmatic hernia (CDH). TO induces lung growth, but even when performed minimally invasive, there is a risk for iatrogenic preterm delivery. Whenever this is anticipated, maternal glucocorticoids (GC) may be given to enhance lung maturation. The pulmonary effects of GC in fetuses with CDH that underwent TO are yet poorly defined. Therefore, we conducted a placebo-controlled study in the nitrofen (NF) rat model for CDH. Pregnant rats were gavage fed NF or olive oil (OO) on ED9.5. At ED19.0, fetuses were either assigned to TO or left untouched. Maternal betamethasone (BM) or saline (PLAC) was administered on ED20. Necropsy was done on ED21.5 to obtain lung-to-body-weight ratio (LBWR), and perform quantitative RT-PCR and fluorescent immunostaining for Ki-67 and proliferating cell nuclear antigen (PCNA) in fetal lungs. CDH fetuses had a lower LBWR than normal fetuses, but comparable pulmonary PCNA and Ki-67 expression levels. TO increased LBWR, irrespective of maternal BM or PLAC. However, BM but not PLAC inhibited proliferation in TO and unoperated fetuses. Rats with NF-induced CDH have hypoplastic lungs with normal proliferation indices. TO triggers proliferation, an effect countered by BM.

550: Placebo controlled study on effect of intratracheal instillation of albumin prior to tracheal occlusion in nitrofen rats with CDH

ALBUMIN PRIOR TO TRACHEAL OCCLUSION IN NITROFEN RATS WITH CDH PHILIPP KLARITSCH, LOURENCO SBRAGIA, JAAN TOELEN, STEFFI MAYER, XENIA ROUBLIOVA, JAN DEPREST, Katholieke Universiteit Leuven, Center for Surgical Technologies, Leuven, Belgium, University Hospitals Leuven, Pediatrics, Leuven, Belgium, University Hospitals Leuven, OB/GYN, Leuven, Belgium OBJECTIVE: Tracheal Occlusion (TO) promotes lung growth in fetuses with severe Congenital Diaphragmatic Hernia (CDH). Still 45% succumb, mainly to persistent hypoplasia. Lung response to TO may be enhanced by increasing lung liquid production by instilling an oncotic agent. We investigated the effect of albumin in addition to TO in a rat model for CDH. STUDY DESIGN: Time dated Wistar rats were fed nitrofen on E9.5. Only fetuses that had CDH at birth were taken into account. At E19 fetuses were assigned to four groups: 1:CDH fetuses who were left untouched; 2:TO fetuses i.e. CDH fetuses undergoing TO; 3: TOAlb i.e. TO fetuses with prior tracheal injection of 50 L of 20% albumin or 4: 50 il of 0.9%NaCl (TOSal). On E21.5 fetuses were harvested to measure wet lung-to-body-weight ratio (LBWR), airway morphometry (linear intercept (Lm; inversely related to air space size); mean terminal bronchiolar density (MTDB); septal thickness (Lmw). RESULTS: Lung to body weight ratio was higher in all TO groups, but in TO-Alb increase was the largest (p 0.05 ANOVA). TO decreases the number of respiratory bronchioli (ns for TOSal), coinciding with increased air space size (Lm), which was less prominent in TO rats. Decrease of septal thickness (Lmw) was equal in all TO groups. CONCLUSION: Fetal rats with CDH have hypoplastic lungs. TO reverses this, which is enhanced by 20% albumin but not placebo. This demonstrates that there is more than additional lung inflation by Sal/Alb next to effect of TO. The airway morphometry changes leave questions prompting for new studies with more sensitive measures of proliferation, interstitial changes and functional tests before implementation.