Clinical and experimental aspects of lung development and injury in congenital diaphragmatic hernia

Congenital anomalies are expressions of abnormal growth and development. They presently form the second most frequent cause of death, after immaturity, in the perinatal period. Congenital diaphragmatic hernia (CDH) is a congenital anomaly manifesting itself in about one in 3,000 total births or one in 2,700 live births. More than 95% of the diaphragmatic defects are posterolateral ones. For a long time CDH was considered as a purely anatomical defect of the diaphragm. But it has become clear that in many cases (ranging from 39 to 47%) it is associated with other anomalies, especially cardiac defects. Despite improved neonatal intensive care, the overall survival rate does still not exceed 55 to 58%, and is even less in patients with associated anomalies. However, higher survival rates have been reported: Wung and coworkers reported a survival rate of 94% in a group of CDH patients who were treated with very delayed surgery and a respiratory care strategy that avoids pulmonary overdistension. The studies reported in this thesis were conducted to investigate various, related aspects of lung development and lung injury in CDH

Esophageal atresia: Long-term morbidities in adolescence and adulthood

Survival rates in esophageal atresia (EA) patients have reached 90%. In long-term follow-up studies the focus has shifted from purely surgical or gastrointestinal evaluation to a multidisciplinary approach. We evaluated the long-term morbidity in adolescent and adult EA patients and discussed mainly nonsurgical issues. Dysphagia is common and reported in up to 85% of patients. In young adults gastroesophageal reflux disease occurs frequently with development of Barrett esophagus in 6% reported in different series. It is difficult to estimate respiratory morbidity from the literature because many different definitions, questionnaires, and study designs have been used. However, many patients seem to suffer from respiratory problems even into adulthood. In conclusion, morbidity is not only restricted to surgical problems but many different domains are involved. These are all related and together determine to a large extent the quality of life of EA patients and also of their families. We assume that a multidisciplinary care approach seems best to address their special needs

Assessment and significance of long-term outcomes in pediatric surgery

Treatment modalities for newborns with anatomical congenital anomalies have greatly improved over the past decades, with a concomitant increase in survival. This review will briefly discuss specific long-term outcomes to illustrate, which domains deserve to be considered in long-term follow-up of patients with anatomical congenital anomalies. Apart from having disease-specific morbidities these children are at risk for impaired neurodevelopmental problems and school failure, which may affect participation in society in later life. There is every reason to offer them long-term multidisciplinary follow-up programs. We further provide an overview of the methodology of long-term follow-up, its significance and discuss ways to improve care for newborns with anatomical congenital anomalies from childhood into adulthood. Future initiatives should focus on transition of care, risk stratification, and multicenter collaboration

Pulmonary neuroendocrine cells in neonatal rats with congenital diaphragmatic hernia

Lung hypoplasia and persistent pulmonary hypertension are the principal causes of high mortality and morbidity in infants with congenital diaphragmatic hernia (CDH). Amine-and peptide-producing pulmonary neuroendocrine cells (PNEC), widely distributed throughout the airway mucosa, are thought to play an important role in both pulmonary development and regulation of pulmonary vascular tone. Furthermore, recent studies show increased levels of calcitonin gene-related peptide (CGRP), a pulmonary vasodilator produced by PNEC, during chronic hypoxia. The article reports data on morphometric analysis of CGRP immunoreactive PNEC clusters (neuroepithelial bodies, NEB) in a rat model of CDH. CDH was induced in neonatal Sprague Dawley rats by oral administration of 2,4-dichloro-phenyl- p-nitro-phenylether (Nitrofen; Rohm Haas, Philadelphia, PA) to the mother at 10 days of gestation. Sections of lungs from term neonatal rats with and without CDH and controls were immunostained for CGRP (marker of NEB) with specific antibody against rat CGRP. NEB size and number of NEB/area of lung were assessed using a semiautomatic image analysis system. In lungs of neonatal rats with CDH, the number of NEB per surface area of lung parenchyma was significantly increased compared with the age-matched controls. Although the mean size of NEB was larger in CDH, the differences were not significant. This is the first study of PNEC in CDH. Whether the phenomenon observed in this study results in altered NEB function including imbalance in vasoactive mediators requires further studies, especially in the human being

Calcitonin gene-related peptide expression is altered in pulmonary neuroendocrine cells in developing lungs of rats with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is associated with high neonatal mortality from lung hypoplasia and persistent pulmonary hypertension. Pulmonary neuroendocrine cells (PNEC) produce calcitonin gene-related peptide (CGRP), a potent vasodilator. We previously reported altered distribution of CGRP-positive PNEC in full-term rats with CDH, that may lead to an imbalance in vasoactive mediators. In the present study we examined the expression of CGRP-positive PNEC during lung development in rats with CDH induced by 2,4-dichlorophenyl-p-nitrophenylether (Nitrofen). Cesarean sections were performed on Days 16, 18, 20, or 22, and the lungs were immunostained for CGRP and immunoreactive cells were quantitated through image analysis. On Day 16, CGRP-immunoreactive staining was negative; on Day 18, CGRP-immunoreactive cells were found in all controls (not exposed to Nitrofen), whereas in CDH pups, CGRP-positive cells were present in only four of six cases. On Day 20, CGRP immunoreactivity was similar in CDH pups, Nitrofen-exposed pups without CDH, and controls. On Day 22 (term), significantly more CGRP-positive cells (i.e., number of positive cells per surface area [mm2] or lung volume [mm3]) were found in ipsilateral lungs of CDH pups than in controls (P < 0.05). The difference was even more striking in contralateral lungs of CDH pups (P < 0.001), ruling out nonspecific effects of Nitrofen. In CDH lungs, the proportion of immunostained epithelium and the size of the neuroendocrine cell clusters (neuroepithelial bodies [NEB]) were not significantly different from those of controls. On Day 22, supraoptimal dilution immunocytochemistry yielded similar results in CDH pups and controls. We conclude that in CDH, CGRP expression in PNEC and NEB is delayed during early stages of lung development. Because CGRP also exhibits growth factor-like properties for endothelium and epithelial cells, the lack of this factor during a crucial developmental stage (canalicular period) may be causally related to lung hypoplasia

Long-term pulmonary sequelae in children with congenital diaphragmatic hernia.

Neonates with congenital diaphragmatic hernia (CDH) often suffer from respiratory insufficiency due to lung hypoplasia and pulmonary hypertension. Artificial ventilation is frequently required, and this leads to a high incidence of bronchopulmonary dysplasia. Long-term follow-up studies have shown persisting airway obstruction. To evaluate the long-term pulmonary sequelae in CDH, we studied 40 CDH patients of age 7 to 18 yr (median 11.7 yr) and 65 age-matched controls without CDH and lung hypoplasia who underwent similar neonatal treatment. Mild airway obstruction was found in both groups with more peripheral airway obstruction in CDH patients than in control subjects. Both groups had normal TLC and single-breath carbon monoxide diffusion capacity (DLCO). CDH patients had increased residual volume (RV) and RV/TLC compared with controls. Increased airway responsiveness to methacholine (MCH) was common but bronchoconstriction to inhaled metabisulfite (MBS) was rare both in CDH and control subjects. We conclude that this group of CDH patients has minor residual lung function impairment. Mild airway obstruction and increased airway responsiveness to inhaled MCH but not to MBS suggest that structural changes in distal airways are involved and not autonomic nerve dysfunction. Both artificial ventilation in the neonatal period and residual lung hypoplasia seem important determinants of persistent lung function abnormalities in CDH patients

Clinical variables as indicative factors for endoscopy in adolescents with esophageal atresia

Introduction: Gastro-esophageal reflux disease (GERD) occurs frequently in patients operated for esophageal atresia (EA). Longstanding esophagitis may lead to dysphagia, strictures, columnar metaplasia, and dysplasia with an increased risk of adenocarcinoma. Are clinical factors and non-invasive assessments reliable indicators for follow-up with endoscopy? Material and method: A follow-up study with inclusion of EA adolescents in Norway born between 1996 and 2002 was conducted. Clinical assessment with pH monitoring, endoscopy with biopsies, along with interviews and questionnaires regarding gastroesophageal reflux disease (GERD) and dysphagia were performed. Results: We examined 68 EA adolescents. 62% reported GERD by interview, 22% by questionnaire. 85% reported dysphagia by interview, 71% by questionnaire. 24-hour pH monitoring detected pathological reflux index (RI) (&gt;7%) in 7/59 (12%). By endoscopy with biopsy 62 (92%) had histologic esophagitis, of whom 3 (4%) had severe esophagitis. Gastric metaplasia was diagnosed in twelve (18%) adolescents, intestinal metaplasia in only one (1.5%). None had dysplasia or carcinoma. Dysphagia and GERD were statistically correlated to esophagitis and metaplasia, but none of the questionnaires or interviews alone were good screening instruments with high combined sensitivity and specificity. A compound variable made by simply taking the mean of rescaled RI and dysphagia by interview showed to be the best predictor of metaplasia (85% sensitivity, 67% specificity). Conclusion: The questionnaires and interviews used in the present study were not good screening instruments alone. However, combining dysphagia score by interview and RI may be helpful in assessing which patients need endoscopy with biopsy at each individual follow-up examination.</p

Evaluation of lung function changes before and after surfactant application during artificial ventilation in newborn rats with congenital diaphragmatic hernia

Patients with congenital diaphragmatic hernia (CDH) have unilateral or bilateral hypoplasia of the lungs including delayed maturation of the terminal air sacs. Because these lungs are highly susceptible to barotrauma and oxygen toxicity, even in full-term newborns, continued research into optimal ventilatory regimen is essential to improve survival rate and to prevent ongoing lung damage. Against this background, the effect of exogenous surfactant application is evaluated. In newborn rats, CDH was induced after a single dose of 2,4 dichloro-4'-nitrophenyl (Nitrofen) (400 mg/kg) on day 10 of gestation. The newborn rats were intubated immediately after hysterotomy, transferred to a heated multichambered body plethysmograph, and artificially ventilated. Inspiratory peak pressures were initially set at 17 cm H2O, with positive end-expiratory pressure at 0 cm H2O and FIO2at 1.0. The pressure was raised in steps of 5 cm H2O, from 5 to 30 cm H2O, to obtain pressure- volume diagrams at 0, 1, and 6 hours of artificial ventilation. These measurements were obtained in controls and in CDH rats with and without endotracheal installation of bovine surfactant (n = 4 to 10 in each group). Significant differences in lung volume between CDH and control rats were observed at all time-points. Surfactant application had a positive effect on lung volume, especially in control rats at t = 1 hour. No significant differences were observed between the CDH groups at t = 1 or t = 6 hours. In this animal model, the effect of artificial ventilation as well as the beneficial short-term effect of exogenous surfactant application have been evaluated. A continued positive effect on lung volume in CDH lungs could not be determined. Routine administration of exogenous surfactant in human CDH patients is not supported by these experimental results

Prenatal hormones alter antioxidant enzymes and lung histology in rats with congenital diaphragmatic hernia.

Prenatal administration of dexamethasone (Dex) and thyrotropin-releasing hormone (TRH) synergistically enhances lung maturity, but TRH suppresses the antioxidant enzyme activity. Prenatal hormonal therapy improves alveolar surfactant content and lung compliance in rats with congenital diaphragmatic hernia (CDH). In full term neonatal rats with CDH we studied the effects of prenatal Dex or Dex+TRH on antioxidant enzyme activity at birth, on survival, and on lung morphometry after 4 h of ventilation with 100% O2. CDH was induced by administration of 2,4-dichlorophenyl-p-nitro-phenylether (Nitrofen) on gestational day 10. Dex+TRH-treated CDH rats had lower activity of glutathione reductase after birth than did sham-treated CDH pups. Dex-treated and sham-treated pups had similar antioxidant enzyme activity. Hormonal treatment did not change survival during ventilation. The average airspace volume increased in Dex-treated CDH pups after ventilation, with a small synergistic effect after addition of TRH. On the basis of our findings, we speculate that prenatal administration of Dex is the best choice to improve lung maturity and airspace volume in CDH patients

Memory deficits following neonatal critical illness: A common neurodevelopmental pathway

Summary Over the last decade, knowledge has emerged that children growing up after neonatal critical illness, irrespective of underlying diagnosis, are at risk of memory impairment and school problems. Strikingly, these problems are manifest even when intelligence is normal. In this review, we propose a common neurodevelopmental pathway following neonatal critical illness by demonstrating that the survivors of preterm birth, congenital heart disease, and severe respiratory failure, share an increased risk of long-term memory deficits and associated hippocampal alterations. Rather than being a consequence of underlying diagnosis, we suggest that this shared vulnerability is most likely related to common conditions associated with neonatal critical illness. These include hypoxia, neuroinflammation, stress, exposure to anaesthetics, or a complex interplay of these factors at different postconceptional ages. Future work should be aimed at improving early identification of patients at risk and evaluating intervention modalities, such as cognitive or exercise training