Infant pulmonary function in a randomized trial of fetal tracheal occlusion for severe congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia: Pulmonary Hypertension and Pulmonary Vascular Disease

This review provides a comprehensive summary of the current understanding of pulmonary hypertension (PH) in congenital diaphragmatic hernia, outlining the underlying pathophysiologic mechanisms, methods for assessing PH severity, optimal management strategies, and prognostic implications.

Pulmonary hypertension in congenital diaphragmatic hernia: ANTENATAL PREDICTION AND IMPACT ON NEONATAL MORTALITY

OBJECTIVE

To determine the prevalence of pulmonary hypertension(PAH) in left-sided congenital diaphragmatic hernia(CDH); how we could predict it; and how PAH contributed to the model for mortality prediction.

STUDY DESIGN

Retrospective analysis in three European centers. The primary outcome was the presence of PAH on postnatal day(d)1,7, and at discharge. Studied predictors of PAH were: observed/expected-lung/head-ratio(o/e LHR), liver-herniation, FETO, and gestational age(GA) at delivery. The combined effect of pre-and postnatal variables on mortality was modeled by Cox regression.

RESULTS

Of the 197 neonates, 56(28.4%) died. At d1, 67.5%(133/197) had PAH and 61.9% (101/163) by d7. Overall, 6.4% (9/141) had PAH at discharge.At d1, o/eLHR(OR 0.96) and FETO(OR 2.99) independently correlated to PAH(AUC:0.74). At d7, PAH significantly correlated only with the use of FETO (OR 3.9;AUC:0.65). None were significant for PAH at discharge.Combining the occurrence of PAH with antenatal biomarkers improved mortality prediction(p=0.02), in a model including o/eLHR(HR:0.94), FETO(HR:0.35), liver herniation(HR:16.78), and PAH(HR:15.95).

CONCLUSIONS

Antenatal prediction of PAH was only moderate. The postnatal occurrence of PAH further increases the risk of death. Whereas this may be used to counsel parents in the postnatal period, our study demonstrates there is a need to find more accurate antenatal predictors for PAH. This article is protected by copyright. All rights reserved.

Impact of Objective Echocardiographic Criteria for Timing of Congenital Diaphragmatic Hernia Repair

OBJECTIVE

To assess the impact of specific echocardiographic criteria for timing of congenital diaphragmatic hernia repair on the incidence of acute postoperative clinical decompensation from pulmonary hypertensive crisis and/or acute respiratory decompensation, with secondary outcomes including survival to discharge, duration of ventilator support, and length of hospitalization.

STUDY DESIGN

The multidisciplinary congenital diaphragmatic hernia management team instituted a protocol in 2012 requiring the specific criterion of echocardiogram-estimated pulmonary artery pressure ≤80% systemic blood pressure before repairing congenital diaphragmatic hernias. A retrospective review of 77 neonatal patients with Bochdalek hernias repaired between 2008 and 2015 were reviewed: group 1 included patients repaired before protocol implementation (n = 25) and group 2 included patients repaired after implementation (n = 52).

RESULTS

The groups had similar baseline characteristics. Postoperative decompensation occurred less often in group 2 compared with group 1 (17% vs 48%, P = .01). Adjusted analysis accounting for repair type, liver herniation, and prematurity yielded similar results (15% vs 37%, P = .04). Group 2 displayed a trend toward improved survival to 30 days postoperatively, though this did not reach statistical significance (94% vs 80%, P = .06). Patient survival to discharge, duration of ventilator support, and length of hospitalization were not different between groups.

CONCLUSIONS

The implementation of a protocol requiring echocardiogram-estimated pulmonary arterial pressure ≤80% of systemic pressure before congenital diaphragmatic hernia repair may reduce the incidence of acute postoperative decompensation, although there was no difference in longer-term secondary outcomes, including survival to discharge.

Increased TGF-β: a drawback of tracheal occlusion in human and experimental congenital diaphragmatic hernia?

Survivors of severe congenital diaphragmatic hernia (CDH) present significant respiratory morbidity despite lung growth induced by fetal tracheal occlusion (TO). We hypothesized that the underlying mechanisms would involve changes in lung extracellular matrix and dysregulated transforming growth factor (TGF)-β pathway, a key player in lung development and repair. Pulmonary expression of TGF-β signaling components, downstream effectors, and extracellular matrix targets were evaluated in CDH neonates who died between birth and the first few weeks of life after prenatal conservative management or TO, and in rabbit pups that were prenatally randomized for surgical CDH and TO vs. sham operation. Before tissue harvesting, lung tissue mechanics in rabbits was measured using the constant-phase model during the first 30 min of life. Human CDH and control fetal lungs were also collected from midterm onwards. Human and experimental CDH did not affect TGF-β/Smad2/3 expression and activity. In human and rabbit CDH lungs, TO upregulated TGF-β transcripts. Analysis of downstream pathways indicated increased Rho-associated kinases to the detriment of Smad2/3 activation. After TO, subtle accumulation of collagen and α-smooth muscle actin within alveolar walls was detected in rabbit pups and human CDH lungs with short-term mechanical ventilation. Despite TO-induced lung growth, mediocre lung tissue mechanics in the rabbit model was associated with increased transcription of extracellular matrix components. These results suggest that prenatal TO increases TGF-β/Rho kinase pathway, myofibroblast differentiation, and matrix deposition in neonatal rabbit and human CDH lungs. Whether this might influence postnatal development of sustainably ventilated lungs remains to be determined.

Prenatal interventions for congenital diaphragmatic hernia for improving outcomes

BACKGROUND

Congenital diaphragmatic hernia (CDH), is an uncommon but severe condition in which there is a developmental defect in the fetal diaphragm, resulting in liver and bowel migrating to the chest cavity and impairing lung development and function for the neonate. This condition can be diagnosed during pregnancy and as such, is potentially amenable to in-utero prenatal intervention. Neonatal surgical repair is possible, but even with early surgical repair and improving neonatal management, neonatal morbidity and mortality is high. Prenatal interventions described to date have included maternal antenatal corticosteroid administration and fetal tracheal occlusion, with both methods aiming to improve lung growth and maturity. However surgical procedures have potential maternal complications, as the uterus and amniotic sac are breached in order to gain access to the fetus.

OBJECTIVES

To compare the effects of prenatal versus postnatal interventions for CDH on perinatal mortality and morbidity, longer-term infant outcomes and maternal morbidity, and to compare the effects of different prenatal interventions with each other.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

All published (including those published in abstract form), unpublished, and ongoing randomised controlled trials comparing prenatal and postnatal interventions for fetuses with CDH. Quasi-RCTs were eligible for inclusion but none were identified. Trials using a cross-over design are not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors evaluated trials for inclusion and methodological quality without consideration of their results according to the stated eligibility criteria and extracted data independently. Data were checked for accuracy.

MAIN RESULTS

We identified 11 studies for potential inclusion. Of those, we included three studies involving 97 women. Two additional studies are ongoing.Two trials examined in-utero fetal tracheal occlusion with standard (postnatal) care in fetuses with severe diaphragmatic hernia. Whilst the trials utilised fetal interventions that were similar, there were important differences in how access was gained to the fetus and in the timing and mode of delivery. Therefore, we did not combine these trials in meta-analysis and the results are examined in separate comparisons. One trial examined the effect of antenatal corticosteroids versus placebo. Overall, the methodological quality of the trials was variable and no data were available for a number of this review's secondary outcomes. In-utero fetal occlusion by maternal laparotomy versus standard postnatal management (one trial, 24 women)For the primary infant outcome (perinatal mortality), there were no data suitable for inclusion in the analysis. There was no difference between groups in terms of long-term infant survival (risk ratio (RR) 1.06, 95% confidence interval (CI) 0.66 to 1.69). In-utero fetal occlusion by minimally invasive fetoscopy versus standard postnatal management (one trial, 41 women)The primary infant outcome (perinatal mortality) was not reported. Minimally invasive fetoscopy was associated with a small reduction in the mean gestational age at birth (mean difference (MD) -1.80 weeks, 95% CI -3.13 to -0.47), but there was no clear difference in the risk of preterm birth before 37 weeks (RR 1.75, 95% CI 0.78 to 3.92). Long-term infant survival (three to six months) (RR 10.50, 95% CI 1.48 to 74.71) was increased with the intervention when compared with standard management, and there was a corresponding reduction in pulmonary hypertension (RR 0.58, 95% CI 0.36 to 0.93) associated with the intervention. There was no difference between groups in terms of preterm ruptured membranes (< 37 weeks) (RR 1.47, 95% CI 0.56 to 3.88) or maternal infectious morbidity (RR 3.14, 95% CI 0.14 to 72.92), and there were no maternal blood transfusions. Antenatal corticosteroids versus placebo (one trial, 32 women)We also included one trial (involving 32 women) examining the effect of antenatal corticosteroids versus placebo. There was no clear difference in the incidence of perinatal mortality (our primary infant outcome) between the group of women who received antenatal corticosteroids and the placebo control (RR 1.24, 95% CI 0.50 to 3.08). Data (mean only) were reported for two of our secondary outcomes (mechanical ventilation and days of hospital admission) but standard deviations (SDs) were not provided. For the purposes of this review and to permit further analysis we have estimated the SDs based on the reported P values reported in the trial report, although our estimation does assume that the SD is the same in both the intervention and control groups. There were no differences between the antenatal corticosteroid group and the placebo control in terms of days of mechanical ventilation (MD 18.00 days, 95% CI -14.77 to 50.77) or days of hospital admission (MD 17.00 days, 95% CI -13.93 to 47.93) .

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to recommend in-utero intervention for fetuses with CDH as a part of routine clinical practice. We identified three small studies, with only one study adequately reporting on the primary outcome of this review - perinatal mortality, and there were few data pertaining to many of this review's secondary outcomes.WIth regard to the administration of antenatal corticosteroids, there remains a gap in current research, and a large multicentre trial with adequate statistical power should be undertaken to answer this unresolved question. More studies are needed to further examine the effect of in-utero fetal tracheal occlusion on important neonatal outcomes and long-term infant survival and health. Long-term follow-up is of particular importance, and should include morbidity and mortality measures. Further studies should examine the benefits of an in-utero intervention on subgroups with moderate and severe congenital diaphragmatic hernia. Indeed, there are three ongoing studies, being conducted by European, North and South American fetal medicine centres, which will contribute to this gap. Ongoing research and any implementation into clinical practice should include standardisation of the procedure, inclusion criteria and long-term childhood follow-up.

Are paediatric operations evidence based? A prospective analysis of general surgery practice in a teaching paediatric hospital

BACKGROUND/AIM

Paediatric surgical practice should be based upon solid scientific evidence. A study in 1998 (Baraldini et al., Pediatr Surg Int) indicated that only a quarter of paediatric operations were supported by the then gold standard of evidence based medicine (EBM) which was defined by randomized controlled trials (RCTs). The aim of the current study was to re-evaluate paediatric surgical practice 16 years after the previous study in a larger cohort of patients.

METHODS

A prospective observational study was performed in a tertiary level teaching hospital for children. The study was approved by the local research ethics board. All diagnostic and therapeutic procedures requiring a general anaesthetic carried out over a 4-week period (24 Feb 2014-22 Mar 2014) under the general surgery service or involving a general paediatric surgeon were included in the study. Pubmed and EMBASE were used to search in the literature for the highest level of evidence supporting the recorded procedures. Evidence was classified according to the Oxford Centre for Evidence Based Medicine (OCEBM) 2009 system as well as according to the classification used by Baraldini et al. Results was compared using Χ (2) test. P < 0.05 was considered statistically significant.

RESULTS

During the study period, 126 operations (36 different types) were performed on 118 patients. According to the OCEBM classification, 62 procedures (49 %) were supported by systematic reviews of multiple homogeneous RCTs (level 1a), 13 (10 %) by individual RCTs (level 1b), 5 (4 %) by systematic reviews of cohort studies (level 2a), 11 (9 %) by individual cohort studies, 1 (1 %) by systematic review of case-control studies (level 3a), 14 (11 %) by case-control studies (level 3b), 9 (7 %) by case series (type 4) and 11 procedures (9 %) were based on expert opinion or deemed self-evident interventions (type 5). High level of evidence (OCEBM level 1a or 1b or level I according to Baraldini et al. PSI 1998) supported 75 (60 %) operations in the current study compared to 18 (26 %) in the study of 1998 (P < 0.0001).

CONCLUSION

The present study shows that nowadays a remarkable number of paediatric surgical procedures are supported by high level of evidence. Despite this improvement in evidence-based paediatric surgical practice, more than a third of the procedures still lack sufficient evidence-based literature support. More RCTs are warranted to support and direct paediatric surgery practice according to the principals of EBM.

Prediction of Neonatal Respiratory Function and Pulmonary Hypertension in Fetuses with Isolated Congenital Diaphragmatic Hernia in the Fetal Endoscopic Tracleal Occlusion Era: A Single-Center Study

Objective: To correlate prenatal indicators of pulmonary hypoplasia with neonatal lung function and pulmonary hypertension (PHT) in isolated congenital diaphragmatic hernia (iCDH). Materials and Methods: Prospective single-center study on 40 fetuses with iCDH either expectantly managed (n = 13) or undergoing tracheal occlusion (n = 27). Prenatal predictors included observed/expected lung-head ratio (O/E LHR), observed/expected total fetal lung volume, fetal pulmonary reactivity to maternal O2 administration (Δpulsatility index, ΔPI) and liver-to-thorax ratio (LiTR) as measured in the second and third trimesters. Postnatal outcome measures included survival until discharge, best oxygenation index (OI) and alveolar-arterial oxygen gradient [D(A-a)O2] in the first 24 h of life and the occurrence of PHT in the first 28 days of life. Results: Median gestational age (GA) at evaluations was 27.2 and 34.3 weeks. GA at delivery was 36.0 weeks, and overall survival was 55%. In the second trimester, measurement of lung size, LiTR and pulmonary reactivity were significantly related to survival and the best OI and D(A-a)O2.The occurrence of PHT was better predicted by ΔPI and LiTR. Conclusions: O/E LHR, LiTR and vascular reactivity correlate with ventilatory parameters in the first 24 h of life. Occurrence of PHT at ≥28 days was best predicted by LiTR and ΔPI, but not by lung size.

Fetoscopic endoluminal tracheal occlusion (FETO) for congenital diaphragmatic hernia in Australia and New Zealand: are we willing, able, both or neither?

AIM

An estimated 140 pregnancies are diagnosed with congenital diaphragmatic hernia (CDH) in Australia and New Zealand each year, with these fetuses having a less than even chance of 1-year survival. Fetoscopic endoluminal tracheal occlusion (FETO) is a relatively new technique that offers a prenatal interventional strategy for selective cases of CDH. This is not routinely offered in Australia or New Zealand. The aim of this systematic review is to critically appraise controlled clinical trials investigating the role of FETO in moderate and severe isolated CDH and explore whether this treatment is justified within our region.

METHODS

A systematic literature search of multiple electronic databases was undertaken, with restrictions to human subjects and controlled clinical trials.

RESULTS

Nine relevant studies were identified. No current evidence was found in favour of FETO for moderate severity CDH. For severe CDH, the most recent evidence demonstrates significantly improved survival following FETO performed using contemporary percutaneous minimally invasive techniques. Optimum timing for balloon insertion, removal and occlusion duration remains conjectural. Substantial variation in survival rates observed among control groups highlights the impact of post-natal care in prenatally diagnosed CDH.

CONCLUSION

Until recently, evidence to support a role for FETO in prenatal CDH management was weak. Recently reported and ongoing controlled trials give cause for optimism, with improved FETO safety and increased survival reported for severe CDH cases. Should Australasia embrace FETO for selected CDH cases, a co-ordinated, evidence-informed service should be established under the guidance of experienced international partnerships.

The ex utero intrapartum treatment (EXIT) procedure: application of a new therapeutic paradigm

The ex utero intrapartum treatment (EXIT) procedure is a term given to a technique that can transform a potentially fatal neonatal emergency to a controlled intervention with an improved outcome. It has revolutionised the care of prenatally diagnosed congenital malformations in which severe upper airway obstruction is anticipated. An extended period of utero-placental circulation can be utilised to avoid profound cardiopulmonary compromise. Its therapeutic applications have been broadened to include fetuses with congenital diaphragmatic hernia after tracheal plugging, high-risk intrathoracic masses, severe cardiac malformations and conjoined twins. It requires the co-ordination of a highly skilled and experienced multidisciplinary team. The recent enthusiasm for the EXIT procedure needs to be balanced against maternal morbidity. Specific indications and guidelines are likely to be refined as a consequence of ongoing advances in fetal intervention and antenatal imaging.

Predictors of neonatal morbidity in fetuses with severe isolated congenital diaphragmatic hernia undergoing fetoscopic tracheal occlusion

OBJECTIVES

To investigate neonatal morbidity in fetuses with severe congenital diaphragmatic hernia (CDH) treated with fetoscopic endoluminal tracheal occlusion (FETO) and compare it with historical controls with less severe forms of CDH that were managed expectantly.

METHODS

This was a prospective, multicenter study on neonatal outcomes and prenatal predictors in 90 FETO survivors (78 left-sided, 12 right) and 41 controls from the antenatal CDH registry with either severe or moderate hypoplasia who were managed expectantly. We also investigated early neonatal morbidity indicators, including the need for patch repair, duration of mechanical ventilation and supplemental oxygen, age at full enteral feeding and incidence of pulmonary hypertension.

RESULTS

Gestational age at delivery was predictive of duration of assisted ventilation (P = 0.046), days on supplemental oxygen (P = 0.019) and age at full enteral feeding (P = 0.020). When delivery took place after 34 weeks' gestation, neonatal morbidity of FETO cases was comparable with that of expectantly managed cases with moderate hypoplasia.

CONCLUSIONS

Fetal intervention for severe CDH is associated with neonatal morbidity that is comparable with that of an expectantly managed group with less severe disease.

Dynamic tracheal occlusion improves lung morphometrics and function in the fetal lamb model of congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is associated with significant neonatal morbidity and mortality. Although prenatal complete tracheal occlusion (cTO) causes hypoplastic CDH lungs to enlarge, improved lung function has not been demonstrated. Furthermore, cTO interferes with the dynamic pressure change and fluid flow associated with fetal breathing.

PURPOSE

The purpose of the study was to assess a novel dynamic tracheal occlusion (dTO) device that preserves pressure changes and fluid flow.

METHODS

In this pilot study, CDH was created in fetal lambs at 65 days of gestational age (GA). At 110 days GA, a cTO device (n = 3) or a dTO device (n = 4) was placed in the fetal trachea. At 135 days GA, lambs were delivered and resuscitated. Unoperated lamb co-twins (n = 5), sham thoracotomy lambs (n = 2), and untreated CDH lambs (n = 3) served as controls.

RESULTS

Tracheal opening pressure, lung volume, lung fluid total protein, and phospholipid were significantly higher in the cTO group than in the dTO and unoperated control groups. Maximal oxygenation and lung compliance were significantly lower in the cTO group when compared with the unoperated control and dTO groups.

CONCLUSION

Preliminary results suggest that in the fetal lamb CDH model, dTO restores normal lung morphometrics and function, whereas cTO leads to enlarged but less functional lungs.

Three-dimensional ultrasound fetal lung volumes and infant respiratory outcome: a prospective observational study

OBJECTIVE

To determine if fetal lung volumes (FLVs), determined by three-dimensional rotational ultrasound and virtual organ computer-aided analysis software (vocal), correlated with neonatal respiratory outcomes in surviving infants who had a high risk [fetuses with congenital diaphragmatic hernia (CDH)], lower risk [fetuses with anterior wall defects (AWDs)] and no risk (controls) of abnormal antenatal lung growth.

DESIGN

Prospective observational study.

SETTING

Tertiary fetal medicine and neonatal intensive care units.

POPULATION

Sixty fetuses (25 with CDH, 25 with AWDs and ten controls).

METHODS

FLVs were measured and expressed as the percentage of the observed compared with the expected for gestational age.

MAIN OUTCOME MEASURES

Neonatal respiratory outcome was determined by the duration of supplemental oxygen, mechanical ventilation and dependencies, and assessment of lung volume using a gas dilution technique to measure functional residual capacity (FRC).

RESULTS

The infants with CDH had lower FLV results than both the infants with AWDs (P=0.05) and the controls (P<0.05). The infants with CDH had longer durations of mechanical ventilation (P<0.001) and supplementary oxygen (P<0.001) dependence, compared with infants with AWDs. The infants with CDH had a lower median FRC than both the infants with AWDs (P<0.001) and the controls (P<0.001). FLV results correlated significantly with the durations of dependency on ventilation (r= -0.744, P<0.01) and oxygen (r= -0.788, P<0.001), and with FRC results (r=0.429, P=0.001).

CONCLUSIONS

These results suggest that FLVs obtained using three-dimensional rotational ultrasound might be useful in predicting neonatal respiratory outcome in surviving infants who had varying risks of abnormal lung growth. Larger and more comprehensive studies are needed to clarify the role that lung volume measurements have in assessing lung function and growth.

Congenital diaphragmatic hernia: endothelin-1, pulmonary hypertension, and disease severity

RATIONALE

Endothelin-1 (ET1) is dysregulated in pulmonary hypertension (PH). It may be important in the pathobiology of congenital diaphragmatic hernia (CDH).

OBJECTIVES

We hypothesized that ET1 levels in the first month would be higher in infants with CDH who subsequently expired or were discharged on oxygen (poor outcome). We further hypothesized that ET1 levels would be associated with concurrent severity of PH.

METHODS

We sampled plasma at 24 to 48 hours, and 1, 2, and 4 weeks of age in 40 prospectively enrolled newborns with CDH. We performed echocardiograms to estimate pulmonary artery pressure at less than 48 hours of age and weekly to 4 weeks. PH was classified in relationship to systemic blood pressure (SBP): less than 2/3 SBP, 2/3 SBP-systemic is related to pressure, or systemic-to-suprasystemic pressure.

MEASUREMENTS AND MAIN RESULTS

ET1 levels at 1 and 2 weeks were higher in infants with poor outcome compared with infants discharged on room air (median and interquartile range: 27.2 [22.6, 33.7] vs. 19.1 [16.1, 29.5] pg/ml, P = 0.03; and 24.9 [17.6, 39.5] vs. 17.4 [13.7, 21.8] pg/ml, P = 0.01 at 1 and 2 weeks, respectively). Severity of PH was significantly associated with increasing ET1 levels at 2 weeks (16.1 [13.7, 21.8], 21.0 [17.4, 31.1], and 23.6 [21.9, 39.5] pg/ml for increasing PH class, P = 0.03). Increasing severity of PH was also associated with poor outcome at that time (P = 0.001).

CONCLUSIONS

Infants with CDH and poor outcome have higher plasma ET1 levels and severity of PH than infants discharged on room air. Severity of PH is associated with ET1 levels.

Prenatal factors in the development of chronic lung disease

Chronic lung disease (CLD), defined as chronic oxygen dependency, is a common outcome of neonatal intensive care. It occurs most frequently in infants born very prematurely, but also in infants born at term who had severe lung disease and those with abnormal antenatal lung growth due particularly to reduction in fetal breathing movements, amniotic fluid volume or intrathoracic space. There are, however, other causes and the importance of antenatal infection/inflammation regarding impairment of antenatal lung growth is increasingly recognised. Affected infants can suffer chronic respiratory morbidity including an excess of respiratory symptoms and lung function abnormalities even in adulthood. Antenatal interventions directed at improving lung growth are available, but require testing inappropriately designed trials with pulmonary function at follow-up as an outcome.

Impaired somatic growth and delayed lung development in infants with congenital diaphragmatic hernia--evidence from a 10-year, single center prospective follow-up study

PURPOSE

In infants with congenital diaphragmatic hernia (CDH), somatic growth and pulmonary development are key issues beyond the time of intensive care treatment. The aim of the study was to investigate the somatic growth and pulmonary function after discharge and to compare CDH patients with a group of matched controls.

METHODS

Anthropometric measurements and lung function tests were performed in 26 infants after surgical repair of CDH and 26 non-CDH intensive care patients, matched for gestational age and birth weight. Spontaneously breathing infants were tested at a mean of 44 weeks postconceptional age (range, 36-58 weeks). Body weight, body length, respiratory rate (RR), tidal volume (V(T)), functional residual capacity by body plethysmography (FRC(pleth)), respiratory compliance (C(rs)), and respiratory resistance (R(rs)) were measured.

RESULTS

The mean (SD) weight gain per week in the CDH infants was significantly lower compared to non-CDH infants (89 [39] g vs 141 [49] g; P = .002). The breathing pattern between both groups differed considerably. In CDH infants, V(T) was significantly lower (P < .001) and RR significantly higher (P = .005). The respiratory compliance was also significantly (P < .001) reduced, whereas R(rs) did not differ significantly. No statistically significant differences were seen in FRC(pleth) related to the body weight between CDH and non-CDH infants (20.3 [4.4] mL/kg vs 21.5 [4.9] mL/kg).

CONCLUSION

Despite apparently well-inflated lungs after surgery, evidence of early and significantly reduced weight gain and impaired lung function in CHD patients should prompt careful dietary monitoring and regular lung function testing.

Changing perspectives on the perinatal management of isolated congenital diaphragmatic hernia in Europe

Congenital diaphragmatic hernia (CDH) should be diagnosed in the prenatal period and prompt referral to a tertiary referral center for imaging, genetic testing, and multidisciplinary counseling. Individual prediction of prognosis is based on the absence of additional anomalies, lung size, and liver herniation. In severe cases, a prenatal endotracheal balloon procedure is currently being offered at specialized centers. Fetal intervention is now also offered to milder cases within a trial, hypothesizing that this may reduce the occurrence of bronchopulmonary dysplasia in survivors. Postnatal management has been standardized by European high-volume centers for the purpose of this and other trials.

Gene expression analysis after prenatal tracheal ligation in fetal rat as a model of stimulated lung growth

PURPOSE

Prenatal tracheal occlusion or ligation (TL) has been proven to accelerate lung growth, but the mechanism of this is poorly understood. To increase understanding of the biological mechanisms involved in growth stimulation after TL in the fetal lung, we performed Global gene expression analysis using microarray technology.

MATERIAL AND METHODS

Sprague-Dawley rats underwent surgery on gestational day 19. After a small hysterotomy, the trachea was mobilized and tied. As controls, we used littermates to manipulated fetuses. On day 21, fetuses were removed and lungs harvested. Global gene expression analysis was performed using Affymetrix Platform and the RAE 230 set arrays (Affymetrix Inc, Santa Clara, Calif). For validation of microarray data, we performed real time polymerase chain reaction (PCR) of the most significant upregulated or downregulated genes, combined with immunohistochemical (IHC) analysis of lung sections.

RESULTS

In the group that underwent TL, several growth factors had an increased expression including connective tissue growth factor (CTGF), insulin-like growth factor 1 (IGF-1), and fibroblast growth factor 18 (FGF-18). Some of the genes that were downregulated in the group that underwent TL compared with controls were surfactant protein A (SP-A), apolipoprotein E (Apo-E), and phospholipase group II A2 (plg2a2). These results could be confirmed with real time PCR and IHC studies.

DISCUSSION

Tracheal occlusion or ligation is a well-documented stimulator of fetal lung growth, and the present study provides novel insights into the underlying molecular mechanisms, with increased expression of genes and proteins with growth factor activity. One of these growth factors, CTGF, has never been previously described in this model. Also, decreased levels of genes involved in surfactant metabolism were observed, providing molecular insights into the decreased surfactant production that is known to occur in TL. Increased understanding of the molecular mechanisms that control lung growth may be the key to develop novel therapeutic techniques to stimulate prenatal and/or postnatal lung growth.

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.

The long-term follow-up of patients with a congenital diaphragmatic hernia: a broad spectrum of morbidity

Congenital diaphragmatic hernia (CDH) is a life-threatening anomaly with a mortality rate of approximately 40-50%, depending on case selection. It has been suggested that new therapeutic modalities such as nitric oxide (NO), high frequency oxygenation (HFO) and extracorporal membrane oxygenation (ECMO) might decrease mortality associated with pulmonary hypertension and the sequelae of artificial ventilation. When these new therapies indeed prove to be beneficial, a larger number of children with severe forms of CDH might survive, resulting in an increase of CDH-associated complications and/or consequences. In follow-up studies of infants born with CDH, many complications including pulmonary damage, cardiovascular disease, gastro-intestinal disease, failure to thrive, neurocognitive defects and musculoskeletal abnormalities have been described. Long-term pulmonary morbidity in CDH consists of obstructive and restrictive lung function impairments due to altered lung structure and prolonged ventilatory support. CDH has also been associated with persistent pulmonary vascular abnormalities, resulting in pulmonary hypertension in the neonatal period. Long-term consequences of pulmonary hypertension are unknown. Gastro-esophageal reflux disease (GERD) is also an important contributor to overall morbidity, although the underlying mechanism has not been fully understood yet. In adult CDH survivors incidence of esophagitis is high and even Barrett's esophagus may ensue. Yet, in many CDH patients a clinical history compatible with GERD seems to be lacking, which may result in missing patients with pathologic reflux disease. Prolonged unrecognized GERD may eventually result in failure to thrive. This has been found in many young CDH patients, which may also be caused by insufficient intake due to oral aversion and increased caloric requirements due to pulmonary morbidity. Neurological outcome is determined by an increased risk of perinatal and neonatal hypoxemia in the first days of life of CDH patients. In patients treated with ECMO, the incidence of neurological deficits is even higher, probably reflecting more severe hypoxemia and the risk of ECMO associated complications. Many studies have addressed the substantial impact of the health problems described above, on the overall well-being of CDH patients, but most of them concentrate on the first years after repair and only a few studies focus on the health-related quality of life in CDH patients. Considering the scattered data indicating substantial morbidity in long-term survivors of CDH, follow-up studies that systematically assess long-term sequelae are mandatory. Based on such studies a more focused approach for routine follow-up programs may be established.

Postnatal management and long-term outcome for survivors with congenital diaphragmatic hernia

Significant advances in the postnatal management of patients with congenital diaphragmatic hernia (CDH) have resulted in a remarkable improvement in survival rates over the past two decades. The success of current postnatal management of CDH patients has rendered fetal intervention to be limited to the most severe cases, and the role for prenatal treatment of CDH patients remains unclear. The adoption of lung-preserving strategies including high-frequency oscillatory ventilation (HFOV) and extracorporeal membrane oxygenation (ECMO) have improved CDH outcomes especially in those patients with significant ventilatory or circulatory compromise. Survival rates of up to 90% are being reported in some high-volume centers. However, the increased survival in CDH patients has been accompanied by an increase in neurological, nutritional and musculoskeletal morbidity among the long-term survivors. This has resulted in the need to provide resources for the long-term follow-up and support of this patient population. In this article, the postnatal management strategies and primary and secondary outcomes of high-volume international pediatric surgical centers will be reviewed. Finally, the role of a multidisciplinary management team for the follow-up of long-term CDH survivors will be discussed.

Fetal tracheal occlusion for severe congenital diaphragmatic hernia in humans: a morphometric study of lung parenchyma and muscularization of pulmonary arterioles

OBJECTIVE

The aim of this study is to examine structure of lung parenchyma (Pp) and muscularization of pulmonary arterioles (PAs) in human fetuses that underwent tracheal occlusion (TO) therapy for severe congenital diaphragmatic hernia (CDH).

MATERIAL

Fifteen fetuses underwent TO, with 5 survivors (Am J Obstet Gynecol. 2000:183;1059-1066). Paraffin-embedded lung specimens from 7 of 10 nonsurvivors (CDH-TO) and 6 age-matched fetuses (CDH) were available for morphometric analysis, which included measurements of point fraction of lung Pp and surface density. The PAs were categorized according to external diameter (<70 microm and 70 <or= 140 microm). Percent medial wall thickness (%MWT) was calculated by dividing raw measurements of MWT by external diameter.

RESULTS

Gestational age at TO was 27.6 +/- 0.9 weeks with a mean duration of TO of 32.6 +/- 6.8 days. Gestational age at delivery (CDH-TO 31.9 +/- 0.9 vs CDH 35.4 +/- 1.8 weeks; P = .18) and postnatal survival time (CDH-TO 20.5 +/- 6.0 vs CDH 18.6 +/- 7.8 days; P = .85) were not significantly different between groups. Tracheal occlusion significantly increased the lung-to-body weight ratio (CDH-TO 13.0 +/- 2.2 vs CDH 6.6 +/- 0.9; P = .02). Tracheal occlusion tended to decrease right-lung Pp (CDH-TO 54.6% +/- 2.6% vs CDH 65.7% +/- 5.9%; P = .05), whereas left-lung Pp was not different between groups (CDH-TO 63.0% +/- 3.5% vs CDH 66.7% +/- 4.1%; P = .51). Surface density of airspaces was not different between groups in either left (CDH-TO 171.3 +/- 16.1 cm(-1) vs CDH 151.1 +/- 8.1 cm(-1); P = .34) or right (CDH-TO 172.0 +/- 10.6 cm(-1) vs CDH 160.8 +/- 3.6 cm(-1); P = .33) lungs. The %MWT in small and large PA was similar between groups.

CONCLUSIONS

Open prenatal TO in human fetuses increased lung growth, as evidenced by an increase in lung weight, but did not improve parenchymal structure or muscularization of PAs.

Pulmonary arteriole muscularization in lambs with diaphragmatic hernia after combined tracheal occlusion/glucocorticoid therapy

OBJECTIVE

A morphometric study was performed to examine the effects of prenatal glucocorticoids, which were administered 48 hours before birth, on muscularization of small pulmonary arterioles (<60 microm diameter) in lambs with diaphragmatic hernia (DH) after fetal tracheal occlusion (TO).

STUDY DESIGN

DH was created in 23 fetal sheep at 65 days gestation. TO was performed in 16 of 24 fetuses between 110 and 140 days of gestation; 9 of the fetuses were exposed prenatally to betamethasone (0.5 mg/kg body weight) 48 hours before delivery. Six sham-operated animals served as controls. Sections of paraffin that were embedded in lung tissues were stained with Elastin-Van Gieson, and the percentage of medial wall thickness (MWT) was determined.

RESULTS

The percentage of MWT in DH lambs (29.6% +/- 1.9%) was increased compared with sham animals (18.1% +/- 1.3%) and was not different from that of DH/TO animals (30.3% +/- 1.7%). In DH/TO + glucocorticoid lambs, the percentage of MWT (24.6% +/- 1.2%) was significantly lower than in the DH/TO group but was higher than the sham group.

CONCLUSION

In fetuses who underwent prolonged TO therapy for severe DH, prenatal glucocorticoid treatment decreased medial hypertrophy of pulmonary arterioles by approximately 19%. We speculate that such structural changes may have contributed to improve gas exchange that was observed in this model.

Congenital diaphragmatic hernia: a systematic review and summary of best-evidence practice strategies

OBJECTIVES

Recent reports suggest that specific care strategies improve survival of infants with congenital diaphragmatic hernia (CDH). This review presents details of care from centers reporting high rates of survival among CDH infants.

STUDY DESIGN

We conducted a MEDLINE search (1995 to 2006) and searched all citations in the Cochrane Central Register of Controlled Trials. Studies were included if they contained reports of >20 infants with symptomatic CDH, and >75% survival of isolated CDH.

RESULT

Thirteen reports from 11 centers met inclusion criteria. Overall survival, including infants with multiple anomalies, was 603/763 (79%; range: 69 to 93%). Survival for isolated CDH was 560/661 (85%; range: 78 to 96%). The frequency of extracorporeal membrane oxygenation (ECMO) use for isolated CDH varied widely among reporting centers 251/622 (40%; range: 11 to 61%), as did survival for infants with isolated CDH placed on ECMO: 149/206 (73%; range: 33 to 86%). There was no suggestion of benefit from use of antenatal glucocorticoids given after 34 weeks gestation or use of postnatal surfactant. Low mortality was frequently attributed to minimizing lung injury and adhering to center-specific criteria for ECMO.

CONCLUSION

Use of strategies aimed at minimizing lung injury, tolerance of postductal acidosis and hypoxemia, and adhering to center-specific criteria for ECMO were strategies most consistently reported by successful centers. The literature lacks randomized clinical trials of these or other care strategies in this complex patient population; prospective studies of safety and long-term outcome are needed.

Antenatal and postnatal lung and vascular anatomic and functional studies in congenital diaphragmatic hernia: implications for clinical management

Congenital diaphragmatic hernia is characterized by fetal and neonatal lung hypoplasia as well as vascular hypoplasia. Antenatal imaging studies have been performed that attempt to quantify the degree of hypoplasia and its impact on infant prognosis. Prenatal and perinatal growth of the lung and vasculature are interdependent and their continued coordinated growth is critical for survival after birth in this patient population. Lung protection strategies appear to improve survival in newborns with diaphragmatic hernia, but a subset of infants remain who demonstrate sufficiently severe lung hypoplasia that we are unable to provide support long-term after birth. Fetal intervention is a strategy designed to enhance fetal lung growth towards improving survival in this most severely affected group, though other therapies to enhance postnatal lung and vascular growth should be concurrently investigated. However, any of these interventions will require careful selection of those infants at risk for poor outcome and thorough follow up, since long-term morbidity is significant in children with diaphragmatic hernia.

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.

Prenatal intervention for congenital diaphragmatic hernia

Advances in prenatal ultrasound have revealed the poor natural history of fetal congenital diaphragmatic hernia (CDH) and its hidden mortality during gestation and immediately after birth. Attempts to improve this poor outcome led to the development of prenatal surgical intervention for severe CDH by Harrison and his colleagues at the University of California San Francisco. Prenatal surgical intervention for CDH has seen four phases: open fetal surgical repair, open surgical tracheal occlusion, endoscopic external tracheal occlusion, and endoscopic endoluminal tracheal occlusion. After extensive work in the laboratory, prenatal intervention has been applied in humans since 1984. With the most recent techniques, maternal risk is significantly reduced as is the incidence of preterm labor. In the meantime, the survival rate of fetuses with CDH without fetal intervention has improved mainly due to the minimization of iatrogenic lung injury by gentle ventilation, first described in 1985. However, the morbidity of the survivors with severe CDH remains high. Prenatal intervention for CDH will be justified if improvement in survival or morbidity can be demonstrated when compared to planned delivery and postnatal management with gentle ventilation strategy.

Lung function in infants after repair of congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Congenital diaphragmatic hernia (CDH) is initially characterized by severe restrictive lung defect and low lung compliance, but survivors have relatively few abnormalities later in life. We studied the changes in lung growth and function in infants after the repair of CDH.

METHODS

Retrospective analysis of pulmonary function tests was performed during the first 24 months of life in 56 infants (33 male and 23 female) after repair of CDH. Lung function (functional residual capacity [FRC], respiratory system compliance [C(rs)] and resistance [R(rs)], and maximum expiratory flow rate at FRC [V'(maxFRC)]) were compared among 4 different ages (0-3, 4-6, 7-12, and 13-24 months).

RESULTS

All indices of lung function (mean +/- SD of z scores) were abnormal during the first 6 months of life but were almost normalized by 24 months (P < .0001): FRC, from -0.84 +/- 0.5 to 3.26 +/- 2.07; C(rs), from -0.87 +/- 0.4 to 1.84 +/- 1.75; R(rs), from 2.85 +/- 2.71 to -0.23 +/- 2.03, and V'(maxFRC), from -1.63 +/- 0.4 to -0.09 +/- 0.94. There was significant correlation (P < .001) between lung function and increase in age, height, and especially weight.

CONCLUSIONS

Lung growth and function gradually normalize between 6 and 24 months of life after repair of CDH.

Prenatal intervention for isolated congenital diaphragmatic hernia

PURPOSE OF REVIEW

We aim to review the recent literature regarding early prenatal prediction of outcome in babies diagnosed with isolated congenital diaphragmatic hernia, as well as results of fetal therapy for this condition.

RECENT FINDINGS

Current survival rates in population-based studies are around 55-70%. Highly specialized centers report 80% and more, but discount the hidden mortality, mainly in the antenatal period. Fetuses presenting with liver herniation and a lung-to-head ratio of less than 1.0 measured in midgestation have a poor prognosis. Other volumetric techniques are being evaluated for use in midtrimester. Recently, a randomized trial failed to show benefit from prenatal therapy, but lacked power to document the potential advantage of prenatal therapy in severe cases. We proposed percutaneous fetal endoluminal tracheal occlusion with a balloon at 26-28 weeks through a 3.3 mm incision. In severe cases, fetal endoluminal tracheal occlusion increased lung size as well as survival, with an early (7 day) survival, late neonatal (28 day) survival and survival at discharge of 75, 58 and 50%, respectively, comparing favorably with 9% in contemporary controls. Airways can be restored prior to birth improving neonatal survival (83.3% compared with 33.3%). The procedure carries a risk for preterm prelabour rupture of the fetal membranes, although that may decrease with experience.

SUMMARY

Fetuses with severe congenital diaphragmatic hernia can be identified in the second trimester. Fetal endoluminal tracheal occlusion can be considered as a minimally invasive fetal therapy, improving outcome in such highly selected cases.

Fetal surgery for congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) continues to account for significant mortality in neonates. Advances in postnatal therapies have reduced mortality rates in the less severely affected infants, though surviving infants continue to display significant comorbid conditions. The history of fetal treatment for CDH is a microcosm for the development of fetal therapy in general. This paper traces this history from early clinical observations and imaging advances to experimental animal studies and finally to safe human application and development of clinical trails. Encouraging recent results and improved outcomes lend credence to the idea than prenatal interventions may give clinicians and families more hope.

MRI of normal and pathological fetal lung development

Normal fetal lung development is a complex process influenced by mechanical and many biochemical factors. In addition to ultrasound, fetal magnetic resonance imaging (MRI) constitutes a new method to investigate this process in vivo during the second and third trimester. The techniques of MRI volumetry, assessment of signal intensities, and MRI spectroscopy of the fetal lung have been used to analyze this process and have already been applied clinically to identify abnormal fetal lung growth. Particularly in conditions such as oligohydramnios and congenital diaphragmatic hernia (CDH), pulmonary hypoplasia may be the cause of neonatal death. A precise diagnosis and quantification of compromised fetal lung development may improve post- and perinatal management. The main events in fetal lung development are reviewed and MR volumetric data from 106 normal fetuses, as well as different examples of pathological lung growth, are provided.

Congenital diaphragmatic hernia: searching for answers

BACKGROUND

Pulmonary hypoplasia and hypertension are the primary causes of morbidity and mortality in infants with congenital diaphragmatic hernia (CDH). At present, the origin of CDH and the causes of pulmonary hypoplasia and hypertension are unknown.

DATA SOURCES

This article reviews the available published data regarding the origin of CDH and the pathogenesis of the associated pulmonary hypertension and hypoplasia. These investigations have employed human tissues as well as two types of CDH animal models.

CONCLUSIONS

Investigations performed to date have not yet provided definitive answers regarding the pathogenesis of CDH. However, they have yielded many new and exciting discoveries and several opportunities for intervention. Ongoing research should open new possibilities to improve the outcome for these unfortunate babies with CDH.