Severe diaphragmatic hernia treated by fetal endoscopic tracheal occlusion

OBJECTIVES

To examine operative and perinatal aspects of fetal endoscopic tracheal occlusion (FETO) in congenital diaphragmatic hernia (CDH).

METHODS

This was a multicenter study of singleton pregnancies with CDH treated by FETO. The entry criteria for FETO were severe CDH on the basis of sonographic evidence of intrathoracic herniation of the liver and low lung area to head circumference ratio (LHR) defined as the observed to the expected normal mean for gestation (o/e LHR) equivalent to an LHR of 1 or less.

RESULTS

FETO was carried out in 210 cases, including 175 cases with left-sided, 34 right-sided and one with bilateral CDH. In 188 cases the CDH was isolated and in 22 there was an associated defect. FETO was performed at a median gestational age of 27.1 (range, 23.0-33.3) weeks. The first eight cases were done under general anesthesia, but subsequently either regional or local anesthesia was used. The median duration of FETO was 10 (range, 3-93) min. Successful placement of the balloon at the first procedure was achieved in 203 (96.7%) cases. Spontaneous preterm prelabor rupture of membranes (PPROM) occurred in 99 (47.1%) cases at 3-83 (median, 30) days after FETO and within 3 weeks of the procedure in 35 (16.7%) cases. Removal of the balloon was prenatal either by fetoscopy or ultrasound-guided puncture, intrapartum by ex-utero intrapartum treatment, or postnatal either by tracheoscopy or percutaneous puncture. Delivery was at 25.7-41.0 (median, 35.3) weeks and before 34 weeks in 65 (30.9%) cases. In 204 (97.1%) cases the babies were live born and 98 (48.0%) were discharged from the hospital alive. There were 10 deaths directly related to difficulties with removal of the balloon. Significant prediction of survival was provided by the o/e LHR and gestational age at delivery. On the basis of the relationship between survival and o/e LHR in expectantly managed fetuses with CDH, as reported in the antenatal CDH registry, we estimated that in fetuses with left CDH treated with FETO the survival rate increased from 24.1% to 49.1%, and in right CDH survival increased from 0% to 35.3% (P < 0.001).

CONCLUSIONS

FETO in severe CDH is associated with a high incidence of PPROM and preterm delivery but a substantial improvement in survival.

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.

Prenatal prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia: a multicenter study

OBJECTIVES

To investigate the value of the observed to expected fetal lung area to head circumference ratio (o/e LHR) and liver position in the prediction of neonatal morbidity in survivors with congenital diaphragmatic hernia (CDH).

METHODS

Neonatal morbidity was recorded in 100 consecutive cases with isolated CDH diagnosed in fetal medicine units, which were expectantly managed in the prenatal period, were delivered after 30 weeks and survived until discharge from hospital. Regression analysis was used to identify the significant predictors of morbidity, including prenatal and immediate neonatal findings.

RESULTS

The o/e LHR provided significant prediction of the need for prosthetic patch repair, duration of assisted ventilation, need for supplemental oxygen at 28 days, and incidence of feeding problems. An additional independent prenatal predictor of the need for patch repair was the presence of fetal liver in the chest.

CONCLUSIONS

In isolated CDH the prenatally assessed size of the contralateral lung is a significant predictor of the need for prosthetic patch repair, the functional consequences of impaired lung development and occurrence of feeding problems.

Effects of betamethasone on peripheral arterial development in term fetal rabbit

Glucocorticoids are given antenatally to promote pulmonary epithelial maturation and prevent respiratory distress syndrome in premature newborns. In contrast to airway changes, effects on vessels are less documented. We hypothesized that antenatal betamethasone (BM) administration promotes vascular development. Does received either a course of BM = 0.05 mg/kg/day (18 does, 70 fetuses), BM = 0.1 mg/kg/day (20 does, 75 fetuses), or saline (11 does, 92 fetuses) starting on d25, 26 (canalicular stage), d27, d28 (saccular stage), and d29 (alveolar stage) of gestation. In total 236 fetuses from 49 does were examined at term (d31) in terms of vascular development. Lung specimens were weighed and formalin fixed for morphometry. We determined differences in fetal body, liver and lung weight, proportionate medial thickness, muscularization of intra-acinar vessels, number of vessels under 100 microm, as well as immunoreactivity to Flk-1 in vascular smooth muscle and endothelial cells. A dose-dependent reduction in neonatal body and organ weight was observed in fetuses exposed to BM at d25. In contrast, term liver weight increased after late administration of BM (d28, 29). There was a dose- and time-dependent thinning of the pulmonary arterial media, which coincided with a decreased proportion of intra- and pre-acinar muscularized arteries (ED <or= 60 microm) and increased microvascularization (ED <or= 30), as well as increased endothelial immunoreactivity for Flk-1. Analyzing our data using a purpose designed geometrical model, the results suggest that maternal administration of BM promotes changes in vascular morphology, which may be compatible with remodeling and vessel formation.

Fetal lung volume after endoscopic tracheal occlusion in the prediction of postnatal outcome

OBJECTIVE

The objective of the study was to investigate the volume response of the contralateral lung in the prediction of postnatal outcome in fetuses with congenital diaphragmatic hernia (CDH) treated by fetoscopic endotracheal occlusion (FETO).

STUDY DESIGN

In 30 fetuses with isolated severe CDH that underwent FETO, the volume of the contralateral lung was measured by 3-dimensional ultrasound the day before and 2 and 7 days after FETO. The measurements of fetuses that subsequently died were compared to those who survived.

RESULTS

In all fetuses before FETO, the lung volume was below the 2.5th percentile of the normal range for gestation (60%). Within 2 days after FETO, the lung volume increased to above the 2.5th percentile in 14/21 (66%) that survived, compared with 1/9 (11%) that died. The respective percentages at 7 days after FETO were 95% and 11%, respectively.

CONCLUSION

In fetuses with CDH, the lung responsiveness within 2 and 7 days after FETO provides useful prediction of subsequent survival.

Effect of maternal administration of betamethasone on peripheral arterial development in fetal rabbit lungs

OBJECTIVES

Glucocorticoids promote lung maturation and reduce the incidence of respiratory distress syndrome in premature newborns. We hypothesized that betamethasone (BM), which is known to induce thinning of the alveolar walls, would also thin the arterial media and adventitia of intra-parenchymatic vessels in developing rabbit lungs.

STUDY DESIGN

112 fetuses from 21 time-mated, pregnant, giant white rabbits received maternal injections of BM at either 0.05 or 0.1 mg/kg/day on days 25-26 of gestational age. Controls received either saline (10 does, 56 fetuses) or no injection (10 does, 59 fetuses). Fetuses were harvested from day 27 onwards until term (day 31). 44 additional fetuses (8 does) were harvested between days 23 and 26. Endpoints were wet lung-to-body weight ratio, vascular morphometric indices and immunohistochemistry staining for alpha-smooth muscle actin, Flk-1, vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS). ANOVA (Tukey's test) and independent t test (p < 0.05) were used for comparison between BM and saline groups.

RESULTS

Maternal BM injected on days 25-26 to pregnant rabbits induced a significant decrease in fetal body and lung weight and the lung-to-body weight ratio in the preterm pups shortly after injection. BM led to a dose-dependent thinning of the arterial media and adventitia (pulmonary arteries with an external diameter (ED) of <100 microm), to an increase in the percentage of non-muscularized peripheral vessels (ED <60 microm), in eNOS and VEGF immunoreactivity of the endothelial and smooth muscle cells in the pulmonary vessels and to an increase in Flk-1-positive pulmonary epithelial cell density.

CONCLUSIONS

Maternal administration of BM caused thinning of the arterial wall of pulmonary vessels (ED <100 microm) and a decrease in muscularization in peripheral vessels (ED <60 microm). This coincided with increased expression of Flk-1 in the endothelium and smooth muscle cells of the pulmonary arteries. All the effects studied were dose-dependent.

Comparison of fetal lung area to head circumference ratio with lung volume in the prediction of postnatal outcome in diaphragmatic hernia

OBJECTIVES

To compare prediction of postnatal survival in isolated diaphragmatic hernia by prenatal two-dimensional (2D) versus three-dimensional (3D) sonographic assessment of the contralateral lung.

METHODS

The lung area to head circumference ratio (LHR) of the contralateral lung was measured and expressed as a percentage of the normal mean for gestation (O/E) in 47 fetuses with isolated diaphragmatic hernia at 26 (range, 21-36) weeks of gestation. The lung area was measured by tracing the limits of the lungs (LHR trace) and by multiplying the longest diameter by its perpendicular (LHR diameters). The contralateral lung volume was measured by the Virtual Organ Computer-Aided anaLysis method and the O/E was calculated. Regression analysis was used to determine the significance of the LHRs and volume in the prediction of postnatal survival.

RESULTS

The survival rate was 59.6% (28 of 47). There were significant associations between O/E LHR trace and O/E LHR diameters, and between each O/E LHR and O/E volume, but multiple regression analysis demonstrated that significant prediction of survival was provided only by O/E LHR trace and intrathoracic herniation of the liver.

CONCLUSIONS

In diaphragmatic hernia prenatal prediction of postnatal outcome is better by 2D measurement of LHR trace than it is by 3D measurement of lung volume.

Lung Volumes in Fetuses with Congenital Diaphragmatic Hernia: Comparison of 3D US and MR Imaging Assessments

PURPOSE

To prospectively compare three-dimensional (3D) ultrasonography (US) and magnetic resonance (MR) imaging in the assessment of lung volumes in fetuses with congenital diaphragmatic hernia.

MATERIALS AND METHODS

Informed consent was obtained for this ethics committee-approved study. Left and right lung volumes were measured by using the 30 degrees virtual organ computer-aided analysis 3D US technique and a transverse multiplanar T2-weighted MR imaging technique in 43 fetuses with isolated congenital diaphragmatic hernia. Regression analysis was used to determine the significance of the association between the two methods.

RESULTS

The 43 fetuses were assessed in a total of 78 examinations. Median gestational age at the examinations was 28 weeks (range, 18-38 weeks). In all examinations, it was possible to visualize and measure both the ipsilateral and the contralateral lungs with MR imaging. In contrast, with 3D US, the contralateral lung could be measured in all examinations, but the ipsilateral lung could be measured in only 44 (56%) examinations. For the contralateral lungs, there was a significant association between 3D US and MR imaging measurements (r = 0.86, P < .001). Although the mean lung volume measured with 3D US was 25% lower than that measured with MR imaging, the ratio of observed volume to expected normal mean volume for gestation was not significantly different between the two methods (3D US, 0.48; MR imaging, 0.52). In the 44 examinations in which the ipsilateral lung could be measured with both methods, 3D US volumes were not significantly different from MR imaging volumes, and the association was weaker (r = 0.39, P < .05) in the ipsilateral lungs than in the contralateral lungs.

CONCLUSION

For congenital diaphragmatic hernia, 3D US provides a reliable measurement of the contralateral but not the ipsilateral lung.

Lung tissue mechanics predict lung hypoplasia in a rabbit model for congenital diaphragmatic hernia

Several animal models have been proposed to study the pathophysiology of congenital diaphragmatic hernia (CDH). Surgical induction of CDH in fetal rabbits during the pseudoglandular phase has been shown to induce severe pulmonary hypoplasia, but functional studies in this model are scarce. We aimed to measure neonatal pulmonary impedance and related it to the severity of lung hypoplasia. CDH was surgically created in rabbits at 23 days of gestation. Following cesarean delivery at term (31 days) pups were subjected to measurement of total lung capacity (TLC), lung to body weight ratio (LBWR) and lung impedance by forced oscillation technique (FOT). Airway resistance (R(aw)), tissue elastance (H(L)), tissue damping (G(L)), and hysteresivity (eta) (G(L)/H(L)) were calculated from impedance data. Twelve CDH fetuses and 15 controls were available for final analysis. LBWR and TLC were significantly lower in the CDH group compared to gestational and age matched controls (P<0.001). R(aw), H(L), and G(L) were significantly increased in CCDH fetuses. eta and H(L) best reflected lung hypoplasia (LBWR) (r(2) = 0.42 and 0.43; P=0.001), indicating a dominant contribution of lung tissue mechanics to CDH-induced lung hypoplasia. We successfully introduced lung impedance measurement by FOT in neonatal rabbits. Following surgical induction of CDH in the pseudoglandular phase, they have, next to morphological evidence of pulmonary hypoplasia, changes in lung mechanics. Our results for lung tissue mechanics support the concept of delayed pulmonary tissue modeling. We propose to employ functional studies in future experiments when evaluating prenatal interventions aimed at reversing pulmonary hypoplasia.

Fetal Body Volume: Use at MR Imaging to Quantify Relative Lung Volume in Fetuses Suspected of Having Pulmonary Hypoplasia

PURPOSE

To retrospectively determine an algorithm based on fetal body volume (FBV) by using magnetic resonance (MR) imaging to calculate relative lung volume in fetuses with normally developed lungs and prospectively assess the use of this algorithm in predicting pulmonary hypoplasia in the late second and early third trimesters for fetuses at risk for pulmonary hypoplasia.

MATERIALS AND METHODS

Oral informed consent was obtained for the prospective component of this ethics committee-approved study. MR imaging lung volumetry was performed in 36 fetuses with normally developed lungs between 18 and 39 weeks gestational age by using T2-weighted single-shot fast spin-echo imaging in fetal transverse and sagittal planes. Findings were then correlated with biometric variables and gestational age. The best-performing algorithm was applied to 37 fetuses (between 18 and 29 weeks gestational age) at risk for pulmonary hypoplasia to determine observed-expected lung volume ratio. This group was stratified according to pregnancy management, and observed-expected ratios were correlated with outcome. In fetuses with isolated congenital diaphragmatic hernia (CDH) (n = 19), observed-expected ratio was correlated with lung-head ratio, neonatal survival in pregnancies managed expectantly (n = 13), and/or lung-body weight ratio at necropsy (n = 9). For that purpose, linear regression correlation was used with the Pearson correlation coefficient; P < .05 was considered to indicate a significant difference.

RESULTS

Total fetal lung volume correlated best with total FBV (r = 0.96, P < .05). Observed-expected ratio based on FBV correlated with lung-head ratio in patients with CDH (r = 0.71, P < .001) and with lung-body weight ratio at necropsy (r = 0.68, P < .05) and could be used to help predict neonatal survival.

CONCLUSION

FBV measured with MR imaging can be used as a single parameter in an algorithm and showed closest correlation with normal total fetal lung volume. In the transition from second to third trimester, this algorithm enabled calculation of the observed-expected ratio and prediction of outcome in fetuses at risk for pulmonary hypoplasia.

Fetal lung-to-head ratio in the prediction of survival in severe left-sided diaphragmatic hernia treated by fetal endoscopic tracheal occlusion (FETO)

OBJECTIVE

The objective of the study was to investigate the value of fetal lung area to head circumference ratio in the prediction of the postnatal outcome in left-sided congenital diaphragmatic hernia treated by fetoscopic endoluminal tracheal occlusion.

STUDY DESIGN

The lung area to head circumference ratio was measured before fetoscopic endoluminal tracheal occlusion in 28 fetuses with congenital diaphragmatic hernia at 25 to 29 weeks. Regression analysis was used to investigate the effect on survival of lung area to head circumference ratio, gestation at fetoscopic endoluminal tracheal occlusion, gestation at delivery, preterm amniorrhexis following fetoscopic endoluminal tracheal occlusion, and prenatal removal of the balloon.

RESULTS

The median lung area to head circumference ratio prior to fetoscopic endoluminal tracheal occlusion was 0.7 (range 0.5 to 0.9). The median gestation at delivery was 34 (range 27 to 39) weeks, and there were 16 survivors (57%). Only lung area to head circumference ratio provided significant prediction of survival, which increased from 17% for lung area to head circumference ratio of 0.4 to 0.5 to 62% for lung area to head circumference ratio of 0.6 to 0.7 and 78% for lung area to head circumference ratio of 0.8 to 0.9.

CONCLUSION

In congenital diaphragmatic hernia treated by fetoscopic endoluminal tracheal occlusion, postnatal survival can be predicted by the lung area to head circumference ratio measured prior to the procedure.

Remifentanil for Fetal Immobilization and Maternal Sedation During Fetoscopic Surgery: A Randomized, Double-Blind Comparison with Diazepam

Obstetric endoscopy procedures are routinely performed at our institution to treat selected complications of monochorionic twin gestation. We perform these procedures under combined spinal epidural anesthesia plus maternal sedation. In the absence of general anesthesia, fetal immobilization is not achieved. We hypothesized that remifentanil would induce adequate maternal sedation and provide fetal immobilization, which is equal or superior to that induced by diazepam. Fifty-four second trimester pregnant women were included in this randomized, double-blind trial. After combined spinal epidural anesthesia, maternal sedation was initiated using either incremental doses of diazepam or a continuous infusion of remifentanil. Maternal sedation, hemodynamics, side effects, and fetal hemodynamics and immobilization were evaluated before, during, and for 60 min after surgery. Remifentanil produced adequate maternal sedation with mild but clinically irrelevant respiratory depression (respiratory rate 13 +/- 4 breaths/min and Pco(2) 38.6 +/- 4 mm Hg at 40 min of surgery), whereas diazepam resulted in a more pronounced maternal sedation but no respiratory depression (respiratory rate 18 +/- 3 breaths/min and Pco(2) 32.7 +/- 3 mm Hg at 40 min of surgery). Compared with diazepam, fetal immobilization with remifentanil occurred faster and was more pronounced, resulting in improved surgical conditions; the number of gross body and limb movements was 12 +/- 4 (diazepam) versus 2 +/- 1 (remifentanil) at 40 min of surgery. Because of this, the mean (range) duration of surgery was significantly shorter in the remifentanil-treated patients, 60 (54-71) min versus 80 (60-90) min in the diazepam group. We conclude that remifentanil produces improved fetal immobilization with good maternal sedation and only minimal effects on maternal respiration.