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

Prostanoids in bronchoalveolar lavage fluid do not predict outcome in congenital diaphragmatic hernia patients

Vasoactive prostanoids may be involved in persistent pulmonary hypertension (PPH) in infants with a congenital diaphragmatic hernia (CDH). We hypothesized that increased levels of prostanoids in bronchoalveolar lavage (BAL) fluid would predict clinical outcome. We measured the concentrations of 6-keto-prostaglandin F1α (6-keto-PGF1α), thromboxane B2 (TxB2), protein, albumin, total cell count, and elastase-α1-proteinase-inhibitor complex in BAL fluid of 18 CDH patients and of 13 control subjects without PPH. We found different concentrations of prostanoids in BAL fluid of CDH patients with PPH: infants with a poor prognosis had either high levels of both 6-keto-PGF1α and TxB2 compared to controls, or high levels of 6-keto-PGF1α only. TxB2 levels showed a large variability in all CDH patients irrespective of outcome. We conclude that prostanoid levels in BAL fluid do not predict clinical outcome in CDH patients

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

Lung eicosanoids in perinatal rats with congenital diaphragmatic hernia

Abnormal levels of pulmonary eicosanoids have been reported in infants with persistent pulmonary hypertension (PPH) and congenital diaphragmatic hernia (CDH). We hypothesized that a dysbalance of vasoconstrictive and vasodilatory eicosanoids is involved in PPH in CDH patients. The levels of several eicosanoids in lung homogenates and in bronchoalveolar lavage fluid of controls and rats with CDH were measured after caesarean section or spontaneous birth. In controls the concentration of the stable metabolite of prostacyclin (6-keto-PGF1α), thromboxane A2 (TxB2), prostaglandin E2 (PGE2), and leukotriene B4 (LTB4) decreased after spontaneous birth. CDH pups showed respiratory insufficiency directly after birth. Their lungs had higher levels of 6- keto-PGF1α, reflecting the pulmonary vasodilator prostacyclin (PGI2), than those of controls. We conclude that in CDH abnormal lung eicosanoid levels are present perinatally. The elevated levels of 6-keto-PGF1α in CDH may reflect a compensation mechanism for increased vascular resistance

Introduction

OBJECTIVE: To evaluate developmental and social-emotional outcomes at 8 years of age for children with congenital diaphragmatic hernia (CDH), treated with or without neonatal extracorporeal membrane oxygenation (ECMO) between January 1999 and December 2003. DESIGN: Cohort study with structural prospective follow-up. SETTING: Level III University Hospital. PATIENTS: 35 children (ECMO: n=16; non-ECMO: n=19) were assessed at 8 years of age. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Intelligence and motor function. Concentration, behaviour, school performance, competence and health status were also analysed. RESULTS: Mean (SD) intelligence for the ECMO group was 91.7 (19.5) versus 111.6 (20.9) for the non-ECMO group (p=0.015). Motor problems were apparent in 16% of all participants and differed significantly from the norm (p=0.015) without differences between treatment groups. For all participants, problems with concentration (68%, p<0.001) and with behavioural attention (33%, p=0.021) occurred more frequently than in reference groups, with no difference between treatment groups. School performance and competence were not affected. CONCLUSIONS: Children with CDH-whether or not treated with neonatal ECMO-are at risk for long-term morbidity especially in the areas of motor function and concentration. Despite their impairment, children with CDH have a well-developed feeling of self-competence

Diagnosis-related deterioration of lung function after extracorporeal membrane oxygenation.

The aim of the study was to assess lung function longitudinally after neonatal extracorporeal membrane oxygenation (ECMO), and to identify any effects of diagnosis and perinatal characteristics. 121 neonatal ECMO-treated children (70 with meconium aspiration syndrome, 20 congenital diaphragmatic hernia and 31 with other diagnoses) performed a total of 191 lung function measurements at 5, 8 and/or 12 yrs. We assessed dynamic and static lung volumes, reversibility of airway obstruction and diffusion capacity. Mean SDS forced expiratory volume in 1 s (FEV(1)) at 5 yrs before and after bronchodilation (-0.51 and 0.07) was significantly higher than at 8 (-0.79 and -0.4; p<0.04) and 12 yrs (-1.10 and -0.52; p<0.003). Mean SDS for all spirometric parameters before and after bronchodilation were significantly lower in the congenital diaphragmatic hernia group compared with the other diagnostic groups (all p</=0.025). A significant volume of trapped air was observed in 86% patients with congenital diaphragmatic hernia, 50% with meconium aspiration syndrome and 58% with other diagnoses. After bronchodilation, mean SDS FEV(1) and forced vital capacity were negatively influenced by duration of ventilation (both p<0.001) and duration of ECMO (p=0.003 and p=0.02, respectively). Long-term pulmonary sequelae after neonatal ECMO-treatment mainly occur in congenital diaphragmatic hernia patients and tend to deteriorate over time