Pulmonary function, exercise performance, and growth in survivors of congenital diaphragmatic hernia

[Safety and efficacy of a therapeutic exercise program in young adults with repaired congenital diaphragmatic hernia]

INTRODUCTION AND OBJECTIVE

Patients with congenital diaphragmatic hernia (CDH) can have up to 40 times more frequency of muskuloskeletal deformities and decreased perception of physical activity tan their pairs. The objective of this study is to evaluate the safety and efficacy of an individualized exercise program in late adolescents and young adults with repaired CDH, as well as a description of their basal status.

MATERIAL AND METHODS

Non randomized prospective trial of 13 patients with repaired CDH between 1997-2005. An initial physical exploration and a pre-post assessment of bioimpedance (BIA), dynamometry, maximal inspiratory and expiratory pressure (MIP/MEP), 6-minute walk test (6MWT), physical activity level (IPAQ) and quality of life (QoL) was made. The training program last for 4 weeks. For the statistical analysis, the Student's t test for paired samples and Wilcoxon test were used.

RESULTS

77% (n=10) were male with a mean age of 19.23±2.13 years. In baseline BIA, 62% (n=8) had truncal sarcopenia that improved in -0.43±0.58, and P=.016. MIP, MEP, 6MWT and QoL tests increased by -7.27±8.26 cmH2O, P=.008; -11.91±10.20 cmH2O, P=.002; -70.63±17.88 m, P=.001; -42,19±26.79, P=.00 respectively. The IPAQ did not change significantly (P=0.86), however the time dedicated to muscle strengthening increased. No adverse effects were reported.

CONCLUSIONS

A personalized rehabilitation program is safe and could improve the respiratory muscle strength and truncal sarcopenia as well as the submaximal effort capacity in late adolescents and young adults with repaired CDH.

Pulmonary outcomes of congenital diaphragmatic hernia patients based on defect size (CDH Study Group Stage)

Background

Congenital diaphragmatic hernia (CDH) is associated with significant pulmonary morbidity. Previous investigation has shown that postnatal inpatient morbidity is linked to diaphragmatic defect size. The objective of this study was to evaluate long-term pulmonary outcomes by CDH study group defect size.

Methods

A retrospective analysis was conducted for CDH patients (n=133) managed in a neonatal intensive care unit (NICU) at a single children's hospital within an adult hospital system and subsequently followed up at a comprehensive multidisciplinary CDH clinic (n=102) from January 2012 to April 2022. CDH patients were stratified according to Congenital Diaphragmatic Hernia Study Group (CDHSG) Stage, and then categorized as low-risk (LR), defect size A and B, or high-risk (HR), defect size C and D. Inpatient data, including the presence of pulmonary hypertension, extracorporeal life support (ECLS) utilization, and mechanical ventilation days, were collected. Post-discharge data including the prevalence of asthma, pulmonary hypertension, emergency department visits, the total number of hospitalizations, and average rehospitalization days were collected. Frequentist analysis was used.

Results

The outcomes for 133 NICU patients were analyzed (HR: n=54, LR: n=79). During NICU stay, the prevalence of pulmonary hypertension [HR: 16/54 (30%) vs. LR: 9/79 (12%), P=0.009], ECLS utilization [HR: 19/54 (35%) vs. LR: 4/79 (5%), P<0.001], and the average number of mechanical ventilation days [HR: 17 days (IQR: 12-27) vs. LR: 5 days (IQR: 2-9), P<0.001] were significantly higher in the HR CDH group. Post NICU discharge, the prevalence of asthma [HR: 20/54 (37%), vs. LR: 17/79 (22%), P=0.050)] and the total days of rehospitalization [HR: 9 (IQR: 2-27) vs. LR: 4 (IQR: 1-8), P=0.035] were significantly higher in HR group. Of the patients seen in the comprehensive multidisciplinary CDH clinic, obstructive lung disease measured by impulse oscillometry was increased in the HR CDH population compared to the reference group [median R5Hz was 12.95 kPa/(L/s) in CDH vs. 9.8 kPa/(L/s) (P=0.010)].

Conclusions

HR CDHSG Stage is associated with worse inpatient and long-term pulmonary outcomes.

Long-term exercise and pulmonary function outcomes in a contemporary cohort of children with congenital diaphragmatic hernia

OBJECTIVE

Congenital diaphragmatic hernia (CDH) survivors are at risk for long-term exercise impairment and pulmonary morbidity, but the generalizability of prior reported cohorts are limited by reduced disease severity and older surgical eras. We assessed the mid-childhood exercise and pulmonary function outcomes in a contemporary cohort of CDH survivors.

STUDY DESIGN

In this retrospective cohort study, we identified 36 consecutive pediatric CDH survivors who underwent cardiopulmonary exercise testing (CPET) and spirometry from 2014 to 2021. Inferential statistics compared survivors with age-, sex-, and size-matched healthy controls; univariate analyses identified factors associated with abnormal testing.

RESULTS

Maximal effort CPET and resting spirometry were completed by 27/36 (75%) and 31/36 (86%) subjects, respectively (median age: 8.1 years [interquartile range: 7.5, 10]; 16 females [44%]). Abnormal CPET (percent predicted [pp] peak VO₂  < 80%) was more common in the CDH cohort (12 vs. 1, p < 0.001) and associated with longer neonatal intensive care unit (NICU) stay (p = 0.02) and oxygen therapy at discharge (p = 0.03). Exercise impairment was mild (pp peak VO₂ 70%-80%), moderate (60%-70%), and severe (<60%) in 6, 4, and 2 survivors, respectively. Abnormal spirometry was more common in the CDH cohort (21 vs. 3, p < 0.001; obstructive [n = 15], restrictive [n = 6]) and associated with decreased gestational age (p = 0.046), longer mechanical ventilation in the NICU (p = 0.02), and orthopedic abnormalities (p = 0.03).

CONCLUSION(S)

Exercise capacity was normal or mildly impaired in most CDH survivors, however, approximately two-thirds demonstrated abnormal spirometry. Impaired exercise capacity and lung function were associated with severity of lung disease postnatally. These data support cardiopulmonary follow-up throughout childhood.

Long term outcomes in CDH: Cardiopulmonary outcomes and health related quality of life

BACKGROUND

With improvements in clinical management and an increase in CDH survivorship there is a crucial need for better understanding of long-term health outcomes in CDH.

AIM

To investigate the prevalence of cardiopulmonary health morbidity and health related quality of life (HRQoL) in CDH survivors.

METHODS

We included all studies (n = 65) investigating long-term cardiopulmonary outcomes in CDH patients more than 2 years published in the last 30 years. The Newcastle-Ottawa Scale and the CASP checklist for cohort studies were utilized to assess study quality. Results were reported descriptively and collated by age group where possible.

RESULTS

The incidence of pulmonary hypertension was highly variable (4.5-38%), though rates (%) appeared to diminish after 5 years of age. Lung function indices and radiological outcomes were frequently abnormal, and Health Related Quality of Life (HRQoL) reduced also. Long term diseases notably emphysema and COPD are not yet fully described in the contemporary literature.

CONCLUSION

This study underscores cardiopulmonary health morbidity and a reduced HRQoL among CDH survivors. Where not already available dedicated multidisciplinary follow-up clinics should be established to support these vulnerable patients transition safely into adulthood. Future research is therefore needed to investigate the risk factors for cardiopulmonary ill health and morbidity in CDH survivors.

TYPE OF STUDY

Systematic review of case control and cohort studies.

Volatile Organic Compounds, Bacterial Airway Microbiome, Spirometry and Exercise Performance of Patients after Surgical Repair of Congenital Diaphragmatic Hernia

The aim of this study was to analyze the exhaled volatile organic compounds (VOCs) profile, airway microbiome, lung function and exercise performance in congenital diaphragmatic hernia (CDH) patients compared to healthy age and sex-matched controls. A total of nine patients (median age 9 years, range 6-13 years) treated for CDH were included. Exhaled VOCs were measured by GC-MS. Airway microbiome was determined from deep induced sputum by 16S rRNA gene sequencing. Patients underwent conventional spirometry and exhausting bicycle spiroergometry. The exhaled VOC profile showed significantly higher levels of cyclohexane and significantly lower levels of acetone and 2-methylbutane in CDH patients. Microbiome analysis revealed no significant differences for alpha-diversity, beta-diversity and LefSe analysis. CDH patients had significantly lower relative abundances of Pasteurellales and Pasteurellaceae. CDH patients exhibited a significantly reduced Tiffeneau Index. Spiroergometry showed no significant differences. This is the first study to report the VOCs profile and airway microbiome in patients with CDH. Elevations of cyclohexane observed in the CDH group have also been reported in cases of lung cancer and pneumonia. CDH patients had no signs of impaired physical performance capacity, fueling controversial reports in the literature.

In vivo imaging of canine lung deformation: effects of posture, pneumonectomy, and inhaled erythropoietin

Mechanical stresses on the lung impose the major stimuli for developmental and compensatory lung growth and remodeling. We used computed tomography (CT) to noninvasively characterize the factors influencing lobar mechanical deformation in relation to posture, pneumonectomy (PNX), and exogenous proangiogenic factor supplementation. Post-PNX adult canines received weekly inhalations of nebulized nanoparticles loaded with recombinant human erythropoietin (EPO) or control (empty nanoparticles) for 16 wk. Supine and prone CT were performed at two transpulmonary pressures pre- and post-PNX following treatment. Lobar air and tissue volumes, fractional tissue volume (FTV), specific compliance (Cs), mechanical strains, and shear distortion were quantified. From supine to prone, lobar volume and Cs increased while strain and shear magnitudes generally decreased. From pre- to post-PNX, air volume increased less and FTV and Cs increased more in the left caudal (LCa) than in other lobes. FTV increased most in the dependent subpleural regions, and the portion of LCa lobe that expanded laterally wrapping around the mediastinum. Supine deformation was nonuniform pre- and post-PNX; strains and shear were most pronounced in LCa lobe and declined when prone. Despite nonuniform regional expansion and deformation, post-PNX lobar mechanics were well preserved compared with pre-PNX because of robust lung growth and remodeling establishing a new mechanical equilibrium. EPO treatment eliminated posture-dependent changes in FTV, accentuated the post-PNX increase in FTV, and reduced FTV heterogeneity without altering absolute air or tissue volumes, consistent with improved microvascular blood volume distribution and modestly enhanced post-PNX alveolar microvascular reserves.NEW & NOTEWORTHY Mechanical stresses on the lung impose the major stimuli for lung growth. We used computed tomography to image deformation of the lung in relation to posture, loss of lung units, and inhalational delivery of the growth promoter erythropoietin. Following loss of one lung in adult large animals, the remaining lung expanded and grew while retaining near-normal mechanical properties. Inhalation of erythropoietin promoted more uniform distribution of blood volume within the remaining lung.

Congenital diaphragmatic hernia and exercise capacity, a longitudinal evaluation

OBJECTIVE

Children with congenital diaphragmatic hernia (CDH) suffer from long-term pulmonary morbidity. Longitudinal data of exercise capacity in these children are lacking. We hypothesized that exercise capacity would be impaired in children with CDH and deteriorates over time. We evaluated exercise capacity and its determinants in CDH patients longitudinally until 12 years of age.

DESIGN

Prospective longitudinal follow-up study in tertiary university hospital.

PATIENTS

One hundred and fourteen children with CDH born between 1999 and 2012.

METHODS

Exercise capacity was evaluated using the Bruce treadmill-protocol at the ages of 5, 8, and 12 years. Primary outcome parameter was standard deviation score (SDS) of maximal endurance time. Data were analyzed by using linear mixed models.

RESULTS

A total of 107 children (30 treated with extracorporeal membrane oxygenation [ECMO]) performed 191 reliable exercise tests. At ages 5, 8, and 12 years, the mean (95%CI) SDS endurance time was -0.44 (-0.65 to -0.24); -1.01 (-1.23 to -0.78); -1.10 (-1.40 to -0.80), respectively, all less than zero (P < 0.001). Exercise capacity declined significantly over time irrespective of ECMO-treatment (5-12 years: non-ECMO P = 0.015; ECMO P = 0.006). Duration of initial hospital stay and diffusion capacity corrected for alveolar volume were associated with SDS endurance time (P < 0.001 and P = 0.039).

CONCLUSIONS

In CDH patients exercise capacity deteriorates between 5 and 12 years of age, irrespective of ECMO-treatment. CDH patients may benefit from long-term assessments of exercise capacity with timely intervention.

Long-term morbidity of congenital diaphragmatic hernia: A plea for standardization

Congenital diaphragmatic hernia (CDH) survivors present long-term morbidities in several systems, including the neurodevelopmental, gastrointestinal, pulmonary, and musculoskeletal ones, and CDH long-term sequelae are increasingly being recognized. Due to high co-morbidity, health related quality of life in a significant proportion of CDH patients might be compromised. As a consequence of consciousness on the long-term sequelae of CDH survivors, and their consequences for life, several follow-up programs were brought to life worldwide. In this review, we will summarize the long-term sequelae of CDH survivors, the impact of new treatments, and analyze the consistency of follow-up programs.

Comparative analysis of the mechanical signals in lung development and compensatory growth

This review compares the manner in which physical stress imposed on the parenchyma, vasculature and thorax and the thoraco-pulmonary interactions, drive both developmental and compensatory lung growth. Re-initiation of anatomical lung growth in the mature lung is possible when the loss of functioning lung units renders the existing physiologic-structural reserves insufficient for maintaining adequate function and physical stress on the remaining units exceeds a critical threshold. The appropriate spatial and temporal mechanical interrelationships and the availability of intra-thoracic space, are crucial to growth initiation, follow-on remodeling and physiological outcome. While the endogenous potential for compensatory lung growth is retained and may be pharmacologically augmented, supra-optimal mechanical stimulation, unbalanced structural growth, or inadequate remodeling may limit functional gain. Finding ways to optimize the signal-response relationships and resolve structure-function discrepancies are major challenges that must be overcome before the innate compensatory ability could be fully realized. Partial pneumonectomy reproducibly removes a known fraction of functioning lung units and remains the most robust model for examining the adaptive mechanisms, structure-function consequences and plasticity of the remaining functioning lung units capable of regeneration. Fundamental mechanical stimulus-response relationships established in the pneumonectomy model directly inform the exploration of effective approaches to maximize compensatory growth and function in chronic destructive lung diseases, transplantation and bioengineered lungs.

Cardiopulmonary exercise performance is reduced in congenital diaphragmatic hernia survivors

BACKGROUND

Congenital diaphragmatic hernia (CDH) is associated with lung hypoplasia. CDH survivors may have pulmonary morbidity that can decrease cardiopulmonary exercise. We aimed to examine whether cardiopulmonary exercise testing (CPET) results differ in CDH survivors versus healthy age-matched controls and whether CPET results among CDH survivors differ according to self-reported daily activity.

METHODS

In one medical center in Croatia, CDH survivors-patients with surgically corrected CDH who were alive at age 5 years-were invited to participate in spirometry and CPET. Values were compared with those of controls matched 2:1 by age and sex for each CDH survivor aged 7 years or older.

RESULTS

Among 27 CDH survivors aged 5-20 years, 13 (48%) had continued symptoms or spirometric evidence of pulmonary disease. Compared with controls (n = 44), survivors (n = 22) had lower peak oxygen consumption (V˙O2 mean [SD], 35.7 [6.9] vs. 45.3 [8.2] ml/kg per min; P < 0.001). At peak exercise, V˙O2/heart rate (P < 0.001), tidal volume (P = 0.005), and minute ventilation (P < 0.001) were lower in survivors, but the maximal respiratory rate was not different (P = 0.72). Among survivors, mean (SD) V˙O2peak (ml/kg per min) differed by self-reported activity level: athletic, 40.3 (5.0); normal, 35.8 (6.5); and sedentary, 32.1 (6.8) (by ANOVA, P = 0.10 across three groups and P = 0.04 athletic vs. sedentary).

CONCLUSION

More than half of CDH survivors continue to have chronic pulmonary disease. CDH survivors had lower aerobic exercise capacity than controls. Self-reporting information on daily activities may identify CDH patients with low V˙O2max who may benefit from physical training. Pediatr Pulmonol. 2016;51:1320-1329. © 2016 Wiley Periodicals, Inc.

Lung Structure and the Intrinsic Challenges of Gas Exchange

Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints.

Multidisciplinary long-term follow-up of congenital diaphragmatic hernia: a growing trend

This literature review discusses the growing trend toward multidisciplinary long term follow-up for congenital diaphragmatic hernia.

Predictors of early lung function in patients with congenital diaphragmatic hernia

PURPOSE

Long-term pulmonary outcomes of congenital diaphragmatic hernia (CDH) have demonstrated airflow obstruction in later childhood. We examined pulmonary function data to assess what factors predict lung function in the first three years of life in children with CDH.

METHODS

This was a retrospective study of patients treated for CDH who underwent infant pulmonary function testing (IPFT) between 2006 and 2012. IPFT was performed using the raised volume rapid thoracoabdominal compression technique and plethysmography.

RESULTS

Twenty-nine neonates with CDH had IPFTs in the first 3years of life. Their mean predicted survival using the CDH Study Group equation was 63%±4%. Fourteen infants (48%) required extracorporeal membrane oxygenation (ECMO). The mean age at IPFT was 85.1±5weeks. Airflow obstruction was the most common abnormality, seen in 14 subjects. 12 subjects had air trapping, and 9 demonstrated restrictive disease. ECMO (p=0.002), days on the ventilator (p=0.028), and days on oxygen (p=0.023) were associated with restrictive lung disease.

CONCLUSION

Despite following a group of patients with severe CDH, lung function revealed mild deficits in the first three years of life. Clinical markers of increased severity (ECMO, ventilator days, and prolonged oxygen use) are correlated with reduced lung function.

Exercise capacity, daily activity, and severity of fatigue in term born young adults after neonatal respiratory failure

Little is known about long-term effects of neonatal intensive care on exercise capacity, physical activity, and fatigue in term borns. We determined these outcomes in 57 young adults, treated for neonatal respiratory failure; 27 of them had congenital diaphragmatic hernia with lung hypoplasia (group 1) and 30 had normal lung development (group 2). Patients in group 2 were age-matched, with similar gestational age and birth weight, and similar neonatal intensive care treatment as patients in group 1. All patients were born before the era of extracorporeal membrane oxygenation, nitric oxide administration, and high frequency ventilation. Exercise capacity was measured by cycle ergometry, daily physical activity with an accelerometry-based activity monitor, and fatigue by the fatigue severity scale. Median (range) VO2peak in mL/kg/min was 35.4 (19.6-55.0) in group 1 and 37.6 (15.7-52.7) in group 2. There was a between-group P-value of 0.65 for exercise capacity. Daily activity and fatigue were also similar in both groups. So, residual lung hypoplasia did not play an important role in this cohort. There were no significant associations between exercise capacity and perinatal characteristics. Future studies need to elucidate whether exercise capacity is impaired in patients with more severe lung hypoplasia who nowadays survive.

What can imaging tell us about physiology? Lung growth and regional mechanical strain

The interplay of mechanical forces transduces diverse physico-biochemical processes to influence lung morphogenesis, growth, maturation, remodeling and repair. Because tissue stress is difficult to measure in vivo, mechano-sensitive responses are commonly inferred from global changes in lung volume, shape, or compliance and correlated with structural changes in tissue blocks sampled from postmortem-fixed lungs. Recent advances in noninvasive volumetric imaging technology, nonrigid image registration, and deformation analysis provide valuable tools for the quantitative analysis of in vivo regional anatomy and air and tissue-blood distributions and when combined with transpulmonary pressure measurements, allow characterization of regional mechanical function, e.g., displacement, strain, shear, within and among intact lobes, as well as between the lung and the components of its container-rib cage, diaphragm, and mediastinum-thereby yielding new insights into the inter-related metrics of mechanical stress-strain and growth/remodeling. Here, we review the state-of-the-art imaging applications for mapping asymmetric heterogeneous physical interactions within the thorax and how these interactions permit as well as constrain lung growth, remodeling, and compensation during development and following pneumonectomy to illustrate how advanced imaging could facilitate the understanding of physiology and pathophysiology. Functional imaging promises to facilitate the formulation of realistic computational models of lung growth that integrate mechano-sensitive events over multiple spatial and temporal scales to accurately describe in vivo physiology and pathophysiology. Improved computational models in turn could enhance our ability to predict regional as well as global responses to experimental and therapeutic interventions.

Long term respiratory outcomes of congenital diaphragmatic hernia, esophageal atresia, and cardiovascular anomalies

Intrathoracic congenital malformations may be associated with long-term pulmonary morbidity. This certainly is the case for congenital diaphragmatic hernia, esophageal atresia and cardiac and aortic arch abnormalities. These conditions have variable degrees of impaired development of both the airways and lung vasculature, with a postnatal impact on lung function and bronchial reactivity. Pulmonary complications are themselves frequently associated to non-pulmonary morbidities, including gastrointestinal and orthopaedic complications. These are best recognized in a structured multidisciplinary follow-up clinic so that they can be actively managed.

Follow-up of the survivors of congenital diaphragmatic hernia

INTRODUCTION

Survivors of congenital diaphragmatic hernia have increased with the introduction of new treatment modalities and have been reported to experience ongoing medical morbidity until adulthood.

AIM

To describe the long-term functional impact of congenital diaphragmatic repair on the survivors of a single institution cohort of newborns over a 14-year period.

METHODS

The follow up medical charts of 39 congenital diaphragmatic hernia survivors treated at a tertiary neonatal intensive care unit, from January 1997 to December 2010, were analyzed.

RESULTS

The median age at follow up was 70 (4-162) months. Gastrointestinal sequelae were the most common with 12 (30.7%) patients affected by failure to thrive. Chronic lung disease occurred in 5 (12.8%) patients, neurodevelopmental delay in 5 (12.8%), musculoskeletal sequelae in 6 (15.3%), recurrence of hernia in 4 (10.2%) and 2 (7.6%) were deceased.

CONCLUSION

Congenital diaphragmatic hernia survivors are a group of patients that requires long term periodic follow up in a multidisciplinary setting to provide adequate support and improve their quality of life.

Physical activity, fitness, and dyspnea perception in children with congenital diaphragmatic hernia

We assessed whether physical activity could influence the performance and perception of dyspnea in children who were operated on for high risk congenital diaphragmatic hernia (CDH). We hypothesized that CDH children with normal activity would have better lung function and exercise performance level when compared to sedentary CDH subjects. We studied 18 children (11 males and 7 females, mean age 6.6 ± 2.6 years) who were surgically corrected. All children underwent physical examination, ECG at rest, and a maximal exercise stress test on a treadmill to measure the duration of exercise, maximal heart rate and blood pressure, maximal oxygen uptake (VO(2)  max and VO(2)  ml/kg/min). Lung function testing to measure forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV(1) ), and peak expiratory flow (PEF) was also performed. Following the stress test, the Dalhousie dyspnea and effort scale was shown to children as a pictorial panel with three groups of increasing (from 1 to 7) levels of effort perception, throat discomfort, and chest dyspnea. Children were divided into group A (sedentary) and group B (regular physical participation). There was no difference in CDH severity between the two groups. Group A had a statistically significant lower duration of exercise (P < 0.01), maximal oxygen consumption (VO(2)  max P < 0.0001), VO(2)  ml/kg/min (P < 0.001), higher throat closing feeling (P < 0.004), chest dyspnea (P < 0.001), and effort perception (P < 0.04) compared to group B. No differences were found in lung function tests. In conclusion, our data may suggest that children with a history of CDH who are active maintain a higher level of performance with less perception of dyspnea and effort.

Bronchopulmonary innervation defects in infants and rats with congenital diaphragmatic hernia

INTRODUCTION

Pulmonary morbidity in survivors of congenital diaphragmatic hernia (CDH) is caused by hypoplasia, barotraumas, or other reasons. We have previously shown deficient tracheal innervation in rats with CDH. Now we examine whether bronchopulmonary innervation is also abnormal in both infants and rats with CDH.

MATERIAL AND METHODS

Sections of E15, E18, and E21 rat lungs were immunostained for Protein gene product 9.5 and S100 antibodies. Similar immunostaining was performed on tissue from infants dying from CDH (n = 6) and other causes (n = 6) with Neurofilament, S100, and Rearranged during transfection antibodies. Nerve trunks/bronchus were counted, and the proportion of glial and RET-positive cells/bronchial surface was calculated. Glial cell-line derived neurotrophic factor protein and mRNA were measured in rat lungs.

RESULTS

Nerve trunks/bronchus were decreased in infants and rat fetuses with CDH. In contrast, glial and RET-positive cells/bronchial surface were increased in infants and rats with CDH. Both lungs were equally affected. GDNF protein was high, whereas GDNF mRNA was decreased in preterm animals with CDH.

CONCLUSIONS

The lungs of infants and rats with CDH have decreased neural components compensated by increased supporting glial cells and persistence high expression of RET and GDNF protein. Because bronchopulmonary innervation controls airway smooth muscle, vessels, and glandular secretions, it is tempting to hypothesize that these deficiencies might play a role in respiratory morbidity in CDH.

A prospective comparative evaluation of persistent respiratory morbidity in esophageal atresia and congenital diaphragmatic hernia survivors

PURPOSE

The aim of the study was to compare long-term respiratory morbidity in children after repair of esophageal atresia (EA) or congenital diaphragmatic hernia (CDH).

PATIENTS AND METHODS

Children were seen at 6, 12, and 24 months and 5 years within a prospective longitudinal follow-up program in a tertiary children's hospital. Respiratory morbidity and physical condition were evaluated at all moments. At age 5 years, pulmonary function and maximal exercise performance were tested.

RESULTS

In 3 of 23 atresia patients and 10 of 20 hernia patients, bronchopulmonary dysplasia was developed. Seventeen atresia and 11 hernia patients had recurrent respiratory tract infections mainly in the first years of life. At age 5, 25% of EA and CDH patients measured showed reduced forced expiratory volume in 1 second (z-score < -2). Both atresia and hernia patients showed impaired growth, with catch-up growth at 5 years in patients with EA but not in those with hernia. Maximal exercise performance was significantly below normal for both groups.

CONCLUSIONS

Esophageal atresia and CDH are associated with equal risk of long-term respiratory morbidity, growth impairment, and disturbed maximal exercise performance. Prospective follow-up of EA patients aimed at identifying respiratory problems other than tracheomalacia should be an integral part of interdisciplinary follow-up programs.

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.

Reproducibility of cardioventilatory measurements using a respiratory mass spectrometer

The aim of this study was to assess the within subject reproducibility of cardioventilatory measurements and the maximum permitted 'normal' variability over time at rest and exercise using the respiratory mass spectrometer (RMS). Ten subjects underwent an incremental exercise test on three separate occasions utilising rebreathing (RB) and helium dilution mixed expired gas analysis (HME) functions of the RMS. Measurements included heart rate (HR), oxygen consumption (V(O2)), carbon dioxide excretion (V(VO2)), effective pulmonary blood flow (Q(eff)), stroke volume (SV), arteriovenous oxygen content difference (AVO), transfer factor (Dl(CO)), functional residual capacity (FRC), minute ventilation (VE), tidal volume (VT) and respiratory quotient (RQ). The coefficients of variation for each variable for the 10 subjects were calculated. At rest, the 90th centile variability for measured cardiopulmonary variables (RB only) was <35%. During exercise, the 90th centile for variability for measured cardiopulmonary variables for HME and RB were < or =20 and <40%, respectively. These measurements in healthy adults should inform sample size in research studies.

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.

Long-term follow up of infants with congenital diaphragmatic hernia

With improving treatment strategies for congenital diaphragmatic hernia (CDH) infants, an increase in survival of more severely affected patients can be expected. Consequently, more attention is now focused on long-term follow up of these patients. Many reports have emphasized associated morbidity, including pulmonary sequelae, neurodevelopmental deficits, gastrointestinal disorders, and other abnormalities. Therefore, survivors of CDH remain a complex patient population to care for throughout infancy and childhood, thus requiring long-term follow up. Much information has been provided from many centers regarding individual institutional improvements in overall survival. Few of these, however, have reported long-term follow up. The aim of this review is to describe the long-term outcome of survivors with CDH and to suggest a possible follow-up protocol for these patients.

Pulmonary function and exercise testing in adult survivors of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is accompanied by pulmonary hypoplasia and structural abnormalities of the pulmonary vascular bed. It is unknown whether pulmonary function, exercise capacity, and gas exchange during exercise are impaired in adult CDH survivors. The objective of this study was to assess the long-term pulmonary function, exercise capacity, and gas exchange during exercise and relate these findings with quality of life. Of the 23 patients eligible for this study, 12 adult CDH survivors (mean age, 24.3 +/- 4.1 years) with high-risk CDH agreed to participate. Pulmonary function tests, diffusion capacity, and a cardiopulmonary exercise test (CPET) were performed. The FEV1 (mean z-score +/- SD; -1.30 +/- 1.37), FEF25-75% (-1.49 +/- 1.14), and the KCO (-1.03 +/- 1.24) were found to be lower in CDH survivors. The RV/TLC ratio (28.2% +/- 5.0%) was found to be higher. Despite these abnormalities, percent predicted work load (102% +/- 17.2%) and percent predicted maximal oxygen uptake (90.8% +/- 18.9%) were normal in most of the patients. The quality of life of CDH survivors, assessed with the SF-36 questionnaire, is comparable to the general population. Comparison of participants to non-participants did not reveal significant differences in clinical characteristics. In this first study assessing pulmonary function in adult survivors of CDH, mild airway obstruction was observed in most of the patients together with a slightly reduced diffusion capacity for CO. Exercise capacity and gas exchange parameters were normal in this group, indicating that patients do not have a physical impairment, as reflected by a normal quality of life of CDH patients.

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.

Resting and exercise cardiorespiratory function in survivors of congenital diaphragmatic hernia

Our objective was to study exercise capacity and cardiorespiratory response to exertion in survivors of congenital diaphragmatic hernia (CDH). This was a cross-sectional cohort study of 23 CDH survivors, aged 10-16 years, and 23 gender- and age-matched controls. Exercise testing was performed on a cycle ergometer, with cardiac output measurements made using exponential CO2 rebreathing. Pretest cardiorespiratory assessment was done by echocardiography and pulmonary function testing. Statistical analysis was performed using Student's t-test, regression analysis, and longitudinal model computing with spatial covariance structure. No echocardiographic evidence for pulmonary hypertension was found at rest (right ventricular systolic pressures, 27 +/- 6 mmHg). Mean pulmonary artery diameter on the side of the CDH was significantly smaller than contralaterally, but was within normal range (z-score, 0 +/- 1.1 vs. 1.2 +/- 1.6, P < 0.01). Exercise capacity was mildly reduced in CDH compared to controls and predictive data (maximum workload, 77% +/- 12% vs. 91% +/- 16% of predicted, P < 0.01). Cardiorespiratory response to exertion was not significantly different between groups. In conclusion, most adolescent CDH survivors have nearly normal exercise capacity and cardiorespiratory response to exertion. This study may prove useful in comparisons with future cohorts comprising more severely affected individuals now surviving due to improved neonatal care.

Mid- and long-term effects on pulmonary perfusion, anatomy and diaphragmatic motility in survivors of congenital diaphragmatic hernia

The aim of the present study was to evaluate the pulmonary sequelae and diaphragmatic motility in infant, adolescent and adult patients (pts) who had undergone the repair of a congenital diaphragmatic hernia. Thirty-one (81.5%) out of 38 survivors after left side CDH repair, without using a patch, were followed-up. They were subdivided in two groups. Group A (mid-term follow-up): 12 pts (39%) (5 males, 7 females) with a mean age of 4.5 years; Group B (long-term follow-up): 19 pts (61%) (9 males, 10 females) with a mean age of 21.0 years. All pts underwent physical examination, chest X-ray, diaphragmatic ultrasonographic (US) examination, pulmonary perfusion scintigraphy. Patients of the group B were also submitted to spirometry. All pts had a normal life-style and no one complained of respiratory symptoms. The chest X-ray revealed pathologic findings in 12 pts (39%). 8 pts (26%) showed chest wall alterations. The profile of the left diaphragmatic dome appeared irregular in 9 pts (29%). In all pts M-mode sonography disclosed a reduced diaphragmatic motility on the treated side. The mean pulmonary perfusion scintigraphy value on the affected side was 39.2+/-0.7%. The spirometric study showed normal values. We noted that the lung perfusion significantly and rapidly improved after CDH repair even the apparently hypoplastic and small lungs, the diaphragm maintained a good contractility during forced respiration.

Long-term functional evaluation of diaphragmatic motility after repair of congenital diaphragmatic hernia

BACKGROUND/PURPOSE

A few studies have taken into account the diaphragmatic function in patients successfully treated for congenital diaphragmatic hernia (CDH). Monodimensional sonography has been reported to be useful in assessing the diaphragmatic motility. Aim of the present study was to investigate, in a long-term follow-up, the diaphragmatic function after CDH repair.

METHODS

Ten patients, with a mean age of 16 (5-26) years, were enrolled. All had had a left diaphragmatic hernia repaired, but no one received a patch. Ten subjects of matched age were used as controls. The diaphragmatic excursions appear, at M-mode sonography, as a sinusoid; the amplitude of the curve on the vertical axis measured the movement in centimeters. Chest x-ray and spirometry were also performed in CDH patients.

RESULTS

A reduced diaphragmatic motility on the left (treated) side was recorded. The amplitude of the contraction was significantly reduced when compared with the contralateral side (1.19 +/- 0.2 vs 2.33 +/- 0.9 cm; P = .017) and was also significantly reduced in comparison with the motion of the left side of controls (1.19 +/- 0.2 vs 1.83 +/- 0.4 cm; P = .01). There was no difference in the amplitude of contraction between the left and right sides of control patients and between the right side of CDH patients and the controls. Spirometry was normal in all patients but one, who had a slight reduction of ventilation on the left side.

CONCLUSION

M-mode sonography appears as a very useful tool in quantitative evaluation of diaphragmatic movements and should be extensively used during follow-up of patients after CDH repair. Motility of the repaired diaphragmatic is reduced, even after a long period, but this does not affect the respiratory function in patients who survived CDH repair.

Long-term pulmonary morbidity in survivors of congenital diaphragmatic hernia

Our objective was to study long-term respiratory outcomes of congenital diaphragmatic hernia (CDH) treated in the perinatal period. This was a cohort study with 26 adolescent survivors and age- and gender-matched controls. Medical histories were retrieved from hospital charts and questionnaires. Pulmonary function testing included measurement of maximum inspiratory and expiratory pressures (MIPS and MEPS) and maximum voluntary ventilation (MVV). Unpaired two-tailed t-test and nonlinear regression were used for statistical analysis. Significant differences were found in forced expiratory volume in one second (FEV(1)) (79% +/- 16% vs. 94% +/- 10%, P < 0.001), FEF(25-75) (62% +/- 24% vs. 84% +/- 15%, P < 0.001), FRC (114% +/- 20% vs. 95% +/- 13%, P < 0.001), RV/TLC (31% +/- 10% vs. 22% +/- 6%, P < 0.001), MVV (74% +/- 16% vs. 90% +/- 13%, P < 0.001), and MIPS (69% +/- 19% vs. 84% +/- 16%, P < 0.01), with numbers indicating percent predicted of reference values +/- SD. Reduction of MVV was not independent from FEV1 (r = 0.83). Forty-eight percent of patients vs. 4% of controls showed significant improvement of FEV1 after bronchodilators (86% +/- 15 vs. 98% +/- 10, P < 0.01). Forty-six percent of patients had abnormalities of the chest wall or spinal column such as pectus excavatum, pectus carinatum, and scoliosis, mostly mild or moderate. In conclusion, long-term respiratory outcome in adolescent CDH is associated with mild to moderate airway obstruction, a high prevalence of response to bronchodilators, and decreased inspiratory muscle strength. This should guide follow-up scheduling and should be taken into account for perioperative and critical care management.

Long-term pulmonary sequelae in children who were treated with extracorporeal membrane oxygenation for neonatal respiratory failure

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for neonates with intractable respiratory failure, but the long-term pulmonary outcome is unknown. Our aim was to investigate the long-term pulmonary sequelae of these children.

STUDY DESIGN

We studied 50 children at 11.1 +/- 1.1 years (mean +/- SD) who had been treated with neonatal ECMO for meconium aspiration syndrome (38%), sepsis (18%), sepsis with pneumonia (12%), congenital diaphragmatic hernia (12%), congenital heart disease (8%), persistent pulmonary hypertension of the newborn (6%), and respiratory distress syndrome (4%) and 27 healthy controls (10.8 +/- 1.6 years). All subjects completed a respiratory questionnaire and performed pulmonary function and graded cardiopulmonary exercise testing.

RESULTS

Neonatal ECMO survivors had hyperinflation (median residual volume: 131%), airway obstruction (median forced expired volume in 1 second: 79%), lower oxygen saturation with exercise, and lower peak oxygen consumption than controls. The ECMO group achieved similar exercise minute ventilation to controls, with more rapid and shallow breathing. ECMO survivors had an increased frequency of exercise-induced bronchospasm. Those who required higher inspired oxygen tension and ventilator pressures after weaning from ECMO had lower forced expired volume in 1 second and oxygen saturation values.

CONCLUSION

Neonatal ECMO survivors experience lung injury lasting into later childhood. Lung dysfunction correlates with the extent and duration of barotrauma and oxygen exposure as neonates.

Cardiopulmonary anatomy and function in long-term survivors of mild to moderate congenital diaphragmatic hernia

BACKGROUND/PURPOSE

In the last decades, several studies regarding cardiopulmonary sequelae in survivors of congenital diaphragmatic hernia (CDH) have been published, but results often are conflicting, and controversies still exist. The aim of this study was to assess cardiopulmonary anatomic and functional outcome in a group of long-term survivors of CDH of mild to moderate degree.

METHODS

Twenty-four children aged 8.15 +/- 2.80 years underwent clinical examination with growth assessment, chest radiographs, echocardiography, pulmonary perfusion scintigraphy, static lung volumes measurement, and spirometry.

RESULTS

Mean Z scores of weight for age and height for age were within normal values. Echocardiography showed normal anatomy and function in all but 3 patients with isolated CDH, in whom minor alterations were detected. Mean perfusion to the affected side was significantly lower (45.16 +/- 5.30%; P <.0001) but still within normal range. Four children showed a substantial impairment of perfusion to the hernia side. The mean spirometric values and pulmonary volumes were normal. However, a mild restrictive pattern was evident in 6 children (27.3%), an obstructive pattern in 3 (13.6%), and a mixed obstructive and restrictive impairment in 1.

CONCLUSIONS

Hypoplastic lungs of mild to moderate CDH survivors continue to cause pulmonary morbidity in some children many years after the correction of the defect. In particular, lung perfusion appears to be impaired in 20% of the patients and pulmonary function in 45%, without any significant cardiac or developmental sequelae. The negative correlation between FEV1 and duration of ventilation at presentation (r = -0.49; P =.026) may be caused by the consequences of lung hypoplasia, but initial ventilatory management may contribute to increased pulmonary morbidity. Relationship between perfusion and FEF25-75 (r = 0.61; p = 0.004) could reflect an equivalent degree of reduction in the caliber of distal airways and pulmonary vascular tree.

Lessons from a canine model of compensatory lung growth

For over a century, canines have been used to study adaptation to surgical lung resection or pneumonectomy (PNX) that results in a quantifiable and reproducible loss of lung units. As reviewed by Schilling (1965), the first successful experimental pneumonectomies were performed in dogs and rabbits in 1881. By the early 1920s, it was appreciated that dogs can function normally with one remaining lung that increases in volume to fill the thoracic cavity (Andrus, 1923; Heuer and Andrus, 1922; Heuer and Dunn, 1920); these pioneering observations paved the way for surgeons to perform major lung resection in patients. Reports in the 1950s (Schilling et al., 1956) detail surprisingly well-preserved work performance in dogs following staged resection of up to 70% of lung mass. Since then, the bulk of the literature on post-PNX adaptation has shifted to rodents, especially for defining molecular mediators of compensatory lung growth. Because rodents are smaller and easier to handle, more animals can be studied over a shorter duration, resulting in time and cost savings. On the other hand, key aspects of lung anatomy, development, and time course of response in the rodent do not mimic those in the human subject, and few rodent studies have related structural adaptation to functional consequences. In larger mammals, anatomical lung development more closely resembles that in humans, and physiological function can be readily measured. Because dogs are natural athletes, functional limits of compensation can be characterized relatively easily by stressing oxygen transport at peak exercise. Thus, the canine model remains useful for relating structure to function, defining sources and limits of adaptation as well as evaluating therapeutic manipulation. This chapter summarizes key concepts of compensatory lung growth that have been consolidated from canine studies: (i) structure-function relationships during adaptation, (ii) dysanaptic (unequal) nature of compensation, and (iii) signals for initiation of cellular growth.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a lethal human birth defect. Hypoplastic lung development is the leading contributor to its 30-50% mortality rate. Efforts to improve survival have focused on fetal surgery, advances in intensive care and elective delivery at specialist centres following in utero diagnosis. The impact of abnormal lung development on affected infants has stimulated research into the developmental biology of CDH. Traditionally lung hypoplasia has been viewed as a secondary consequence of in utero compression of the fetal lung. Experimental evidence is emerging for a primary defect in lung development in CDH. Culture systems are providing research tools for the study of lung hypoplasia and the investigation of the role of growth factors and signalling pathways. Similarities between the lungs of premature newborns and infants with CDH may indicate a role for antenatal corticosteroids. Further advances in postnatal therapy including permissive hypercapnia and liquid ventilation hold promise. Improvements in our basic scientific understanding of lung development may hold the key to future developments in CDH care.

Exercise testing in children: an alternative approach

In recent years there has been a call for new methods of evaluating the cardiorespiratory responses of children to exercise that complement their everyday exercise patterns. One potential method would be to use a sub-maximal, intermittent, pseudo-random binary sequence (PRBS) exercise test protocol to measure oxygen uptake kinetics (VO2 kinetics). Ten children of mean (SD) age 10.8 (+/- 1.5) years completed a 20 - 50 W cycle ergometer protocol of 17-min duration. An estimate of alveolar oxygen uptake (VO2) was calculated on a breath-by-breath basis. The VO2 kinetic parameters were expressed in the frequency domain as amplitude ratio and phase delay using standard Fourier techniques. Analysis was restricted to the frequency range 2.2 to 8.9 mHz. The mean (SD) amplitude ratio responses decreased from 10.33 (+/- 0.73) to 7.42 (+/- 0.99) ml min(-1) W(-1) and the mean phase delay increased from -26.78 degrees (+/- 6.37 degrees) to -81.93 degrees (+/- 10.45 degrees) over the frequency range 2.2-8.9 mHz. Significant correlations (p < 0.05) were found between chronological age and amplitude ratio (r = 0.68 and 0.62), and chronological age and phase delay (r = -0.62 and -0.69) at the frequencies of 2.2 and 4.4 mHz, respectively. No significant correlations were found between VO2 kinetics and stature or VO2 kinetics and body mass. The observations demonstrated the use of the PRBS technique to measure VO2 kinetics in the frequency domain in children. This approach may be a useful addition to the tests that are used to quantify the oxygen uptake responses to exercise in children.