Congenital diaphragmatic hernia: advances in prenatal therapy

Impact of congenital diaphragmatic hernia on diaphragm muscle function in neonatal rats

Congenital diaphragmatic hernia (CDH) is characterized by incomplete partitioning of the thoracic and abdominal cavities by the diaphragm muscle (DIAm). The resulting in utero invasion of the abdominal viscera into the thoracic cavity leads to impaired fetal breathing movements, severe pulmonary hypoplasia, and pulmonary hypertension. We hypothesized that in a well-established rodent model of Nitrofen-induced CDH, DIAm isometric force generation, and DIAm fiber cross-sectional areas would be reduced compared with nonlesioned littermate and Control pups. In CDH and nonlesioned pups at embryonic day 21 or birth, DIAm isometric force responses to supramaximal field stimulation (200 mA, 0.5 ms duration pulses in 1-s duration trains at rates ranging from 10 to 100 Hz) was measured ex vivo. Further, DIAm fatigue was determined in response to 120 s of repetitive stimulation at 40 Hz in 330-ms duration trains repeated each second. The DIAm was then stretched to L_o, frozen, and fiber cross-sectional areas were measured in 10 μm transverse sections. In CDH pups, there was a marked reduction in DIAm-specific force and force following 120 s of fatiguing contraction. The cross-sectional area of DIAm fibers was also reduced in CDH pups compared with nonlesioned littermates and Control pups. These results show that CDH is associated with a dramatic weakening of the DIAm, which may contribute to poor survival despite various surgical efforts to repair the hernia and improve lung development.NEW & NOTEWORTHY There are notable respiratory deficits related to congenital diaphragmatic hernia (CDH), yet the contribution, if any, of frank diaphragm muscle weakness to CDH is unexplored. Here, we use the well-established Nitrofen teratogen model to induce CDH in rat pups, followed by diaphragm muscle contractility and morphological assessments. Our results show diaphragm muscle weakness in conjunction with reduced muscle fiber density and size, contributing to CDH morbidity.

Mortality following congenital diaphragmatic hernia repair: the role of anesthesia

BACKGROUND

Mortality following surgical repair of congenital diaphragmatic hernia (CDH) remains high. The volume and type of perioperative intravenous fluid administered, baro-trauma, oxygen toxicity, and the duration of anesthesia are thought to affect outcome in surgical populations.

AIMS

The aim of this retrospective observational study was to determine whether the perioperative volume or type of fluids and/or the duration of anesthesia were associated with postoperative mortality and if mortality was predicted by the oxygenation index (OI) prior to or following CDH surgical repair.

METHODS

The records of infants with a left-sided CDH and without other congenital anomalies, who underwent surgical repair between April 2009 and March 2015, were examined. The oxygenation index was used to "quantify" the severity of lung function abnormality and reported as the best OI on day 1 after birth (OI_BEST ), the OI immediately prior to surgery (OI_PRE ) and at 1, 6, 12, and 24 h postsurgery (OI_1h , OI_6h , OI_12h , OI_24h ), respectively. The change in the OI index (delta OI) was calculated by subtracting OI_PRE from postoperative OIs.

RESULTS

The records of 37 CDH infants (median gestational age 35.8, range 31.5-41.4 weeks) were assessed; six died postoperatively. Neither the duration of anesthesia, the volume of crystalloids or colloids administered, nor the peak inflation pressures used during surgical repair were significantly correlated with postoperative mortality. Neither fetal tracheal occlusion nor use of a parietal patch significantly influenced mortality. The postoperative OI_1h , OI_6h , OI_12h showed weak evidence for a difference between survivors and nonsurvivors. An OI_24h of ≥5.5 predicted mortality with 100% sensitivity (95% CI, confidence intervals (CI) 40-100) and 93.1% specificity (95% CI, 77-99).

CONCLUSION

Neither the volume of intraoperative fluids administered nor the duration of anesthesia was associated with postoperative death. The OI 24 h postsurgery was the best predictor of an increased risk of mortality.

Value of liver herniation in prediction of outcome in fetal congenital diaphragmatic hernia: a systematic review and meta-analysis

OBJECTIVES

Intrathoracic liver herniation (ILH) is being used to estimate prognosis and hence guide antenatal interventions in fetal congenital diaphragmatic hernia (CDH). However, the literature regarding its utility in this role is conflicting. This review systematically examines the currently available evidence of ILH use in fetal CDH.

METHODS

MEDLINE and EMBASE databases were searched for the terms ((congenital diaphragmatic hernia) OR CDH) AND liver. Inclusion criteria were human case series of fetuses diagnosed with CDH using either ultrasound or magnetic resonance imaging. Included studies were required to have reported the antenatal liver position and the outcome (survival or not). Case reports, reviews and eventration series were excluded. Studies reporting similar cases from the same center over an overlapping time period were considered duplicates; only the larger of the studies were therefore included. Absolute totals were extracted and sums calculated. Fisher's exact test (FET) was used to compare survival rates in different groups.

RESULTS

The original search retrieved 338 studies. Applying inclusion/exclusion criteria and removing duplicates left 21 case series in 20 studies. Retrieved studies differed in the definitions of liver herniation, survival and treatment modality. In total, there were 407 fetuses in the liver-up (herniated) and 303 in the liver-down (not herniated) groups. Survival rates were 45.4% and 73.9%, respectively. The difference was statistically significant (FET = 56.4, P < 0.005). Sensitivity analysis for cases that had only conventional postnatal treatment was still significant (FET = 52.8, P < 0.005).

CONCLUSIONS

Liver herniation is associated with poorer prognosis in fetal CDH. Grading liver herniation or using it as part of a panel of markers may enhance the value of liver herniation as a prognostic test in fetal CDH.

Is there a role for antioxidants in prevention of pulmonary hypoplasia in nitrofen-induced rat model of congenital diaphragmatic hernia?

BACKGROUND/PURPOSE

Many studies suggest a role for antioxidants in the prevention of lung hypoplasia in nitrofen-induced rat models with congenital diaphragmatic hernia (CDH). This study investigates the oxidative status and the histological outcome of prenatal administration of vitamins E and C with synergistic effect, and effect of N-acetylcysteine (NAC) to improve lung maturation of nitrofen-induced rats.

METHODS

CDH was induced by maternal administration of a single oral dose of nitrofen on day 9.5 of gestation, and the Sprague-Dawley rats were randomly divided into five groups: nitrofen (N), nitrofen + vitamin C (NC), nitrofen + vitamin E (NE), nitrofen + vitamin C + vitamin E (NCE) and nitrofen + NAC (NNAC). A control group in which only vehicle was administered was included. Cesarean section was performed on day 21. Body weight (BW) and total lung weight (LW) of all fetuses with CDH were recorded; lung histological evaluation was performed, and protein content of lungs, determination of thiobarbituric acid reactive substances, and the protein carbonyls in tissue samples were determined.

RESULTS

A total of 133 rat fetuses with CDH were investigated. The body weight and the lung weight of fetuses of all groups that were exposed to nitrofen were significantly decreased than of the control group (P < 0.05). The animals exposed to nitrofen with different antioxidants showed increased protein levels in lung tissue. However, in the NCE and the NNAC groups, protein levels were significantly increased than in the others. Malondialdehyde levels significantly decreased in the NCE and the NNAC groups when compared with the NC and the NE groups. In addition, the NCE and NNAC groups decreased protein oxidation to control levels, and no significant difference was observed between control and these two antioxidants groups. The N, NC, NE and NNAC groups showed minimal improvement in lung histology; the NCE groups showed the most improvement in lung histology when compared with the other nitrofen plus antioxidant groups.

CONCLUSION

Prenatal administration of NAC and vitamin E in combination with vitamin C represented the best effects to avoid oxidative damage and protein content of the lungs in rat pups with CDH at birth.

Congenital diaphragmatic hernia: review of the literature in reflection of unresolved dilemmas

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a rare but clinically and scientifically challenging condition. The introduction of ultrasound has enabled early prenatal detection and consequently, hope of early therapeutic intervention.

AIM

We undertook the task to review the recent developments in understanding the pathology of CDH as well as the history and current management strategies to aid perinatologists in consultations with parents of CDH-affected foetuses.

STUDY DESIGN

A Medline search was undertaken of all reports and reviews published between 1980 and 2008 using MeSH search terms 'diaphragmatic hernia', 'congenital' and 'newborn'.

RESULTS

The true incidence of CDH is still difficult to estimate because of the high incidence of hidden mortality of CDH. Complete case ascertainment also poses difficulties in assessment of the impact of new therapeutic modalities on overall survival. Recent improvements in prenatal detection are a milestone in affording time for re-assessments and parental counselling. The true benefit of antenatal therapy is circumscribed and should be offered only in selected cases of isolated severe CDH as defined by existing guidelines. Postnatal intensive respiratory supportive therapy and innovative surgical techniques within specialized tertiary centres has had a major impact on survival of babies with CDH.

CONCLUSION

The high survival of 'selected cases' that are live births and benefit from optimal care will be difficult to improve by antenatal interventions. The multidisciplinary approach to basic research and randomized clinical trials will further define the best approach to the foetus and neonate with CDH.

Abordagem ventilatória protetora no tratamento da hérnia diafragmática congênita

OBJETIVO: Descrever a evolução de recém-nascidos com diagnóstico de hérnia diafragmática congênita admitidos na Unidade de Terapia Intensiva Neonatal de um hospital privado de nível terciário, no qual aplicou-se uma estratégia ventilatória protetora. MÉTODOS: Coorte histórica com análise de prontuários de pacientes portadores de hérnia diafragmática congênita, admitidos de junho de 2001 a julho de 2006. Avaliaram-se dados referentes ao recém-nascido (índices prognósticos antenatais, peso ao nascimento, idade gestacional, sexo), dados da reanimação e estabililização pré-operatória, cuidados pós-operatórios e taxa de sobrevida. RESULTADOS: Oito neonatos tiveram diagnóstico de hérnia diafragmática congênita. O peso variou entre 2,38 e 3,45kg e a idade gestacional, entre 36 e 39 semanas; cinco deles eram do sexo masculino. Todos foram intubados em sala de parto até o final do primeiro minuto de vida. A correção cirúrgica ocorreu entre o segundo e o sexto dias de vida e, em quatro pacientes, houve necessidade do uso de patch. Uma estratégia ventilatória protetora foi utilizada em seis neonatos, com dados gasométricos visando PaO2 pré-ductal normal e tolerando-se hipercapnia (PaCO2 50 a 60mmHg). A extubação ocorreu entre o primeiro e o 12ºdias do pós-operatório, com exceção de um paciente. Seis recém-nascidos receberam alta, em média, com 30 dias de vida (19 a 55 dias). A sobrevida foi de 75%. CONCLUSÕES: A sistematização do cuidado de pacientes com hérnia diafragmática congênita pode garantir, em nosso meio, uma sobrevida comparável aos principais centros mundiais que lidam com a doença.

H, Daltro PA, Antunes E, Fazecas T, Rodrigues L, Guerra F, Marchiori E, Gasparetto EL, Domingues RC. O valor da ultra-sonografia e da ressonância magnética fetal na avaliação das hérnias diafragmáticas

OBJETIVO: Demonstrar a significância dos achados da ressonância magnética e da ultra-sonografia na caracterização pré-natal e avaliação do prognóstico de pacientes com hérnia diafragmática congênita. MATERIAIS E MÉTODOS: Catorze gestantes (idade gestacional média de 28,7 semanas) examinadas com ultra-sonografia e apresentando fetos com suspeita de hérnia diafragmática congênita foram avaliadas por meio da ressonância magnética. Os exames foram realizados em aparelho de 1,5 tesla usando seqüências-padrão. Dois radiologistas avaliaram as imagens e estabeleceram os achados por consenso. RESULTADOS: Doze fetos tinham hérnia diafragmática à esquerda e dois, à direita. O fígado fetal foi localizado no interior do tórax de cinco fetos pela ultra-sonografia (três com hérnia diafragmática esquerda e dois com hérnia diafragmática direita) e de oito pela ressonância magnética (seis com hérnia diafragmática esquerda e dois com hérnia diafragmática direita). Herniação do estômago e alças de intestino delgado foi observada em todos os fetos com hérnia diafragmática esquerda (n = 12), tanto pela ultra-sonografia quanto pela ressonância magnética. Oito fetos sobreviveram após cirurgia (sete com hérnia diafragmática esquerda e um com hérnia diafragmática direita). CONCLUSÃO: A ultra-sonografia e a ressonância magnética são métodos de imagens complementares na avaliação das hérnias diafragmáticas congênitas. A ressonância magnética pode auxiliar a ultra-sonografia na avaliação da posição do fígado, o qual representa importante fator prognóstico.

Corticosteroids for fetuses with congenital diaphragmatic hernia: can we show benefit?

BACKGROUND AND PURPOSE

Prenatal corticosteroids have been used in fetuses with congenital diaphragmatic hernia (CDH). We tested the utility of steroids by 2 methods.

METHODS

Mothers carrying fetuses with CDH were randomized to 3 weekly doses of betamethasone or placebo starting at 34 weeks. Patients were followed until death or discharge. In a separate cohort study, the CDH Registry was used to compare infants who received prenatal steroids to those who had not.

RESULTS

Thirty-four patients were enrolled at 7 centers, with 32 completing the trial. There were 15 placebo and 17 steroid patients. There was no difference in survival, length of stay, duration of ventilation, or oxygen use at 30 days. For the cohort study, we looked at infants older than 34 weeks who were born after October 2000 when data on prenatal steroids were collected. There were 1093 patients; 390 were evaluable, with 56 receiving steroids. There was no difference in survival, length of stay, ventilator days, or oxygen use at 30 days.

CONCLUSION

Neither the trial nor the CDH Registry suggest that late prenatal corticosteroids benefit fetuses with CDH. More than 1700 mothers and fetuses would need to be enrolled in a trial to show a 10% improvement in survival. It is unlikely that late steroids offer benefit to most fetuses with CDH.

Maternal morbidity after maternal-fetal surgery

OBJECTIVE

There is a paucity of published data on the maternal risks of fetal surgical interventions. We analyzed maternal morbidity and mortality that were associated with different types of fetal intervention (open hysterotomy, various endoscopic procedures and percutaneous techniques) to quantify this risk.

STUDY DESIGN

We performed a retrospective evaluation of a continuous series of 187 cases that had been performed between July 1989 and May 2003 at the Fetal Treatment Center, a highly specialized interdisciplinary center for fetal surgery at the University of California, San Francisco. The primary outcome was the frequency of maternal morbidity for open, endoscopic, and percutaneous procedures to access the fetus.

RESULTS

There were 187 pregnant women with confirmed major fetal malformations who were candidates for intrauterine fetal intervention. Maternal-fetal surgery was performed in 87 cases by open hysterotomy, in 69 cases by endoscopic procedures, and in 31 cases by percutaneous techniques. There were no maternal deaths, but significant short-term morbidity was observed. There were no significant differences in the incidence of premature rupture of membranes, pulmonary edema, placental abruption, postoperative vaginal bleeding, preterm delivery, or interval from maternal-fetal surgery to delivery between endoscopic procedures and open surgery. Complications were significantly less in the percutaneous ultrasound-guided procedures. Endoscopic procedures, even with a laparotomy, showed statistically significantly less morbidity compared with the open hysterotomy group regarding cesarean delivery as delivery mode (94.8% vs 58.8%; P < .001), requirement for intensive care unit stay (1.4% vs 26.4%; P < .001), length of hospital stay (7.9 vs 11.9 days; P = .001), and requirement for blood transfusions (2.9% vs 12.6%; P = .022). Chorion-amnion membrane separation (64.7% vs 20.3%; P < .001) was seen more often in the endoscopy group.

CONCLUSION

Short-term morbidities include increased rates of cesarean birth, treatment in intensive care, prolonged hospitalization, and blood transfusion, all of which were more common with hysterotomy compared with other techniques. Maternal-fetal surgery can be performed without maternal death. Results from this study provide helpful data for counseling prospective patients.

Fetal MRI in experimental tracheal occlusion

Congenital diaphragmatic hernia (CDH) is associated with a high mortality, which is mainly due to pulmonary hypoplasia and secondary pulmonary hypertension. In severely affected fetuses, tracheal occlusion (TO) is performed prenatally to reverse pulmonary hypoplasia, because TO leads to accelerated lung growth. Prenatal imaging is important to identify fetuses with pulmonary hypoplasia, to diagnose high-risk fetuses who would benefit from TO, and to monitor the effect of TO after surgery. In fetal imaging, ultrasound (US) is the method of choice, because it is widely available, less expensive, and less time-consuming to perform than magnetic resonance imaging (MRI). However, there are some limitations for US in the evaluation of CDH fetuses. In those cases, MRI is helpful because of a better tissue contrast between liver and lung, which enables evaluation of liver herniation for the diagnosis of a high-risk fetus. MRI provides the ability to determine absolute lung volumes to detect lung hypoplasia. In fetal sheep with normal and hyperplastic lungs after TO, lung growth was assessed on the basis of cross-sectional US measurements, after initial lung volume determination by MRI. To monitor fetal lung growth after prenatal TO, both MRI and US seem to be useful methods.

[Fetal magnetic resonance imaging. Diagnostics in congenital diaphragmatic hernia]

Ultrasonography is the primary imaging modality for the evaluation of fetal or maternal anomalies. This method is safe, relatively inexpensive, easily accessible, and allows real-time imaging. Continuous technical improvements in ultrasonography in the last 10-15 years have led to improved diagnostic accuracy for fetal malformations. In cases of complex anomalies magnetic resonance imaging (MRI) can provide additional information. MRI has evolved as a valuable diagnostic method for evaluating fetal pathology. Particularly with regard to similarity of liver and lung parenchyma in ultrasonography, diagnosis of congenital diaphragmatic hernia (CDH) can be difficult. Beside morphological aspects, e.g., herniation of abdominal contents into the chest, small amounts of compressed lung can be visualized on MRI. The feasibility of using volumetric measurement on MRI may be helpful to predict high-risk fetuses and facilitate decisions to assure adequate prenatal and postnatal management to improve postnatal outcome.

Fetal surgery for congenital diaphragmatic hernia: the North American experience

The role for fetal surgery in treating fetuses with congenital diaphragmatic hernia (CDH) is unclear. Two decades of investigation have improved our understanding of the prenatal natural history, pathophysiology, and outcomes of these patients. During this same period, there have been advances in fetal surgery techniques including improvements in fetal monitoring, maternal-fetal anesthesia, tocolysis, and improved instrumentation to permit increased application of videoscopic approaches. Because of technical challenges, open fetal repair of CDH has been abandoned. Fetal tracheal ligation has shown promise, but a recently published prospective, randomized trial failed to show a benefit of fetoscopic tracheal ligation compared with expert postnatal treatment. Although there is evidence that postnatal outcomes for infants with this disease have improved with the adoption of gentilation ventilator management, high-frequency ventilation, and ECMO, there continues to be a subset of infants with severe CDH that die or suffer serious long-term morbidity despite advanced surgical care. The purpose of this article is to review issues related to prenatal diagnosis, patient selection, and outcomes for fetal surgery; and ultimately to assess whether there is a role for fetal surgery in treating fetuses with CDH.

Can maternal vitamin e supplementation prevent lung hypoplasia in the nitrofen-induced rat model of congenital diaphragmatic hernia?

Recent studies suggest a role for antioxidants in the prevention of pulmonary hypoplasia associated with congenital diaphragmatic hernia (CDH). We studied the effects of vitamin E in the nitrofen-rat model of CDH. After an initial fast, timed-pregnant Sprague-Dawley rats were gavage-fed nitrofen at gestational day 11 (term is 22 d). On the same day, one group was given a s.c. injection of vitamin E in alcohol; a second group was given an injection of alcohol alone. A third group received no treatment (control). Fetuses were delivered on day 21, and static pressure-volume curves were measured by immersion. Lungs were analyzed for total DNA and protein content by standard methods. A total of 203 fetuses were studied. Of 151 nitrofen-exposed fetuses, 77% had CDH; 92% of these were right-sided. CDH was present in 82% of vehicle-treated fetuses and 71% of vitamin E-treated fetuses (p=0.17). Nitrofen-exposed fetuses not only were smaller than control fetuses but also had disproportionately smaller lungs and poorer lung function, even when CDH was absent; however, lung function was worse when CDH was present. Vitamin E treatment did not improve either lung growth or function, although there was a trend toward less CDH. We have shown, for the first time, that the lung hypoplasia seen in nitrofen-exposed rat fetuses is associated with a dramatic reduction in static lung function, even when CDH is not present. Finally, our findings support the notion that lung hypoplasia in the nitrofen-rat model is independent of CDH formation.

Postnatal lung mechanics, lung composition, and surfactant synthesis after tracheal occlusion vs prenatal intrapulmonary instillation of perfluorocarbon in fetal rabbits

BACKGROUND/PURPOSE

Fetal tracheal occlusion (TO) accelerates lung growth but decreases surfactant production. We have previously shown that instillation of perfluorooctylbromide (PFOB) into fetal rabbit lungs leads to lung growth similar to TO. This study compares neonatal lung mechanics and surfactant production after prenatal intrapulmonary PFOB instillation vs TO.

METHODS

In each of 18 pregnant rabbits on gestational day 27, sets of 4 fetuses underwent either (1) intrapulmonary instillation of 1 mL PFOB, (2) TO, (3) instillation of 1 mL 0.9% NaCl (saline), and (4) hysteroamniotomy without fetal manipulation (control). Fetuses were born by cesarean delivery after 48 hours. Fetuses of 12 rabbits were mechanically ventilated for 15 minutes to evaluate lung compliance and airway resistance. Pulmonary surfactant protein B (SP-B) was quantified by immunohistochemistry in fetuses of the remaining 6 rabbits.

RESULTS

Compliance was decreased in the TO group after cesarean delivery (0.33 +/- 0.13 mL/cm H2O) compared with PFOB (0.59 +/- 0.12 mL/cm H2O), saline (0.50 +/- 0.12 mL/cm H2O), and control (0.52 +/- 0.10 mL/cm H2O) fetuses. Mean fetal lung to body weight ratio was higher in TO and PFOB fetuses compared with saline and control. Higher water content and lower numbers of surfactant protein B-positive cells were found in the TO-treated fetuses.

CONCLUSIONS

Both prenatal intrapulmonary instillation of PFOB and TO accelerate lung growth, but TO is associated with decreased postnatal lung compliance, possibly influenced by decreased surfactant production and increased fluid retention. Conversely, instillation of PFOB preserved lung compliance and surfactant synthesis.

Programmed healing of membranous bone in the fetal lamb

In fetal tissues, both soft and hard tissue healing (in long bones) have been found to be scarless. However, healing of membranous bone in the fetal craniofacial skeleton has not been well documented. Pregnant ewes (gestational age range, 80-95 days) underwent a hysterotomy, and fetal lambs had a full-thickness excision of the entire mandibular symphysis region (10 mm). Nonoperated controls were used for comparison (n = 8). After 10 days and 2 weeks, fetuses showed incomplete regeneration of the anterior mandible by examination, computed tomographic scan, and histology. By 4 weeks postoperatively, the mandibular defect had completely closed, but regenerated bony volume was less than control specimens. At 6 weeks postoperatively, the specimen demonstrated complete bony healing without scar or inflammation. Computed tomographic scan measurements for mandibular shape (length over width) was similar in experimental and control specimens. The data indicate that fetal lamb membranous bone defects heal in a scarless fashion and suggest preprogrammed migration of osteogenic tissue.