Pulmonary function testing in children's interstitial lung disease

The role of respiratory function tests in infants with stridor: diagnosis at glance and follow-up

BACKGROUND

Recently, the development of advanced, noninvasive methods has allowed the study of respiratory function even in uncooperative infants. To date, there is still little data on the application of this technique in infants with suspected airway obstruction.

THE AIMS OF OUR STUDY WERE

- To evaluate the role of respiratory function testing (PFR) in the diagnosis and follow-up of infants with stridor - To evaluate the differences between patients with inspiratory stridor and expiratory stridor. - To evaluate the concordance between PFR and endoscopy.

METHODS

We enrolled infants aged < 1 year with a diagnosis of inspiratory and/or expiratory chronic stridor and a group of healthy controls. For each patient we performed PFR at diagnosis (T0) and for cases at follow-up, at 3 months (T1), 6 months (T2), 12 months (T3). At T0, all patients were classified according to a clinical score, and at follow-up, stature-ponderal growth was assessed. When clinically indicated, patients underwent bronchoscopy.

RESULTS

We enrolled 48 cases (42 diagnosed with inspiratory stridor and 6 expiratory stridor) and 26 healthy controls. At T0, patients with stridor had increased inspiratory time (p < 0.0001) and expiratory time (p < 0.001) than healthy controls and abnormal curve morphology depending on the type of stridor. At T0, patients with expiratory stridor had a reduced Peak expiratory flow (p < 0.023) and a longer expiratory time (p < 0.004) than patients with inspiratory stridor. We showed an excellent concordance between PFR and endoscopic examination (k = 0.885, p < 0.0001). At follow-up, we showed a progressive increase of the respiratory parameters in line with the growth.

CONCLUSIONS

PFR could help improve the management of these patients through rapid and noninvasive diagnosis, careful monitoring, and early detection of those most at risk.

The Clinical Approach to Interstitial Lung Disease in Childhood: A Narrative Review Article

Interstitial lung disease (ILD) comprises a group of respiratory diseases affecting the interstitium of the lungs, which occur when a lung injury triggers an abnormal healing response, and an inflammatory process leads to altered diffusion and restrictive respiratory dysfunction. The term "interstitial" may be misleading, as other components of the lungs are usually also involved (epithelium, airways, endothelium, and so on). Pediatric conditions (childhood interstitial lung disease, chILD) are different from adult forms, as growing and developing lungs are affected and more diverse and less prevalent diseases are seen in childhood. Diffuse parenchymal lung disease (DPLD) and diffuse lung disease (DLD) can be used interchangeably with ILD. Known etiologies of chILD include chronic infections, bronchopulmonary dysplasia, aspiration, genetic mutations leading to surfactant dysfunction, and hypersensitivity pneumonitis due to drugs or environmental exposures. Many forms are seen in disorders with pulmonary involvement (connective tissue disorders, storage diseases, malignancies, and so on), but several conditions have unknown origins (desquamative pneumonitis, pulmonary interstitial glycogenosis, neuroendocrine cell hyperplasia in infancy, and so on). Currently, there is no consensus on pediatric classification; however, age grouping is proposed as some specific forms are more prevalent in infancy (developmental and growth abnormalities, surfactant dysfunction mutations, etc.) and others are usually seen in older cohorts (disorders in normal or immunocompromised hosts, systemic diseases, etc.). Clinical manifestations vary from mild nonspecific symptoms (recurrent respiratory infections, exercise intolerance, failure to thrive, dry cough, etc.) to a severe clinical picture (respiratory distress) and presentation related to the child's age. The diagnostic approach relies on imaging techniques (CT), but further investigations including genetic tests, BAL, and lung biopsy (VATS) are needed in uncertain cases. Pharmacological treatment is mostly empiric and based on anti-inflammatory and immunomodulatory drugs. Lung transplantation for selected cases in a pediatric transplantation center could be an option; however, limited data and evidence are available regarding long-term survival. International collaboration is warranted to understand chILD entities better and improve the outcomes of these patients.

Estimating the effect of nintedanib on forced vital capacity in children and adolescents with fibrosing interstitial lung disease using a Bayesian dynamic borrowing approach

BACKGROUND

The rarity of childhood interstitial lung disease (chILD) makes it challenging to conduct powered trials. In the InPedILD trial, among 39 children and adolescents with fibrosing ILD, there was a numerical benefit of nintedanib versus placebo on change in forced vital capacity (FVC) over 24 weeks (difference in mean change in FVC % predicted of 1.21 [95% confidence interval: -3.40, 5.81]). Nintedanib has shown a consistent effect on FVC across populations of adults with different diagnoses of fibrosing ILD.

METHODS

In a Bayesian dynamic borrowing analysis, prespecified before data unblinding, we incorporated data on the effect of nintedanib in adults and the data from the InPedILD trial to estimate the effect of nintedanib on FVC in children and adolescents with fibrosing ILD. The data from adults were represented as a meta-analytic predictive (MAP) prior distribution with mean 1.69 (95% credible interval: 0.49, 3.08). The adult data were weighted according to expert judgment on their relevance to the efficacy of nintedanib in chILD, obtained in a formal elicitation exercise.

RESULTS

Combined data from the MAP prior and InPedILD trial analyzed within the Bayesian framework resulted in a median difference between nintedanib and placebo in change in FVC % predicted at Week 24 of 1.63 (95% credible interval: -0.69, 3.40). The posterior probability for superiority of nintedanib versus placebo was 95.5%, reaching the predefined success criterion of at least 90%.

CONCLUSION

These findings, together with the safety data from the InPedILD trial, support the use of nintedanib in children and adolescents with fibrosing ILDs.

Imaging of pulmonary fibrosis in children: A review, with proposed diagnostic criteria

Computed tomography (CT) imaging findings of pulmonary fibrosis are well established for adults and have been shown to correlate with prognosis and outcome. Recognition of fibrotic CT findings in children is more limited. With approved treatments for adult pulmonary fibrosis, it has become critical to define CT criteria for fibrosis in children, to identify patients in need of treatment and those eligible for clinical trials. Understanding how pediatric fibrosis compares with idiopathic pulmonary fibrosis and other causes of fibrosis in adults is increasingly important as these patients transition to adult care teams. Here, we review what is known regarding the features of pulmonary fibrosis in children compared with adults. Pulmonary fibrosis in children may be associated with genetic surfactant dysfunction disorders, autoimmune systemic disorders, and complications after radiation, chemotherapy, transplantation, and other exposures. Rather than a basal-predominant usual interstitial pneumonia pattern with honeycombing, pediatric fibrosis is primarily characterized by reticulation, traction bronchiectasis, architectural distortion, or cystic lucencies/abnormalities. Ground-glass opacities are more frequent in children with fibrotic interstitial lung disease than adults, and disease distribution appears more diffuse, without clearly defined axial or craniocaudal predominance. Following discussion and consensus amongst a panel of expert radiologists, pathologists and physicians, distinctive disease features were integrated to develop criteria for the first global Phase III trial in children with pulmonary fibrosis.

Diagnostic workup of childhood interstitial lung disease

Childhood interstitial lung diseases (chILDs) are rare and heterogeneous diseases with significant morbidity and mortality. An accurate and quick aetiological diagnosis may contribute to better management and personalised treatment. On behalf of the European Respiratory Society Clinical Research Collaboration for chILD (ERS CRC chILD-EU), this review summarises the roles of the general paediatrician, paediatric pulmonologists and expert centres in the complex diagnostic workup. Each patient's aetiological chILD diagnosis must be reached without prolonged delays in a stepwise approach from medical history, signs, symptoms, clinical tests and imaging, to advanced genetic analysis and specialised procedures including bronchoalveolar lavage and biopsy, if necessary. Finally, as medical progress is fast, the need to revisit a diagnosis of "undefined chILD" is stressed.

Nintedanib in children and adolescents with fibrosing interstitial lung diseases

BACKGROUND

Childhood interstitial lung disease (ILD) comprises a spectrum of rare ILDs affecting infants, children and adolescents. Nintedanib is a licensed treatment for pulmonary fibrosis in adults. The primary objectives of the InPedILD trial were to determine the dose-exposure and safety of nintedanib in children and adolescents with fibrosing ILD.

METHODS

Patients aged 6-17 years with fibrosing ILD on high-resolution computed tomography and clinically significant disease were randomised 2:1 to receive nintedanib or placebo for 24 weeks and then open-label nintedanib. Dosing was based on weight-dependent allometric scaling. Co-primary end-points were the area under the plasma concentration-time curve at steady state (AUC_τ,ss) at weeks 2 and 26 and the proportion of patients with treatment-emergent adverse events at week 24.

RESULTS

26 patients received nintedanib and 13 patients received placebo. The geometric mean (geometric coefficient of variation) AUC_τ,ss for nintedanib was 175 µg·h·L^-1 (85.1%) in patients aged 6-11 years and 160 µg·h·L^-1 (82.7%) in patients aged 12-17 years. In the double-blind period, adverse events were reported in 84.6% of patients in each treatment group. Two patients discontinued nintedanib due to adverse events. Diarrhoea was reported in 38.5% and 15.4% of the nintedanib and placebo groups, respectively. Adjusted mean±se changes in percentage predicted forced vital capacity at week 24 were 0.3±1.3% in the nintedanib group and -0.9±1.8% in the placebo group.

CONCLUSIONS

In children and adolescents with fibrosing ILD, a weight-based dosing regimen resulted in exposure to nintedanib similar to adults and an acceptable safety profile. These data provide a scientific basis for the use of nintedanib in this patient population.

Pulmonary function in children with persistent tachypnea of infancy

BACKGROUND

Data on the prevalence and type of lung function impairment in preschool and school-aged children previously diagnosed with persistent tachypnea of infancy (PTI) are scarce. Therefore, this study aims to assess pulmonary function in this age group.

METHODS

Children diagnosed with PTI over 3 years old were admitted for follow-up visits and healthy controls were enrolled. The study group included children who were able to complete pulmonary function tests (PFTs). Medical history, physical examination, and pulmonary function (spirometry, body plethysmography, impulse oscillometry, nitrogen multiple breath washout test, diffusing capacity for carbon monoxide [DL_CO ]) were assessed.

RESULTS

Thirty-seven children (26 boys, 11 girls; median age: 5.6 years) diagnosed with PTI and 37 healthy controls were recruited. Forced expiratory volume in 1 s and forced vital capacity were significantly lower (-1.12 vs. 0.48, p = 0.002 and -0.83 vs. 0.31, p = 0.009, respectively); respiratory resistance at 5 Hz (0.06 vs. -0.62, p = 0.003), resonant frequency (1.86 vs. 1.36, p = 0.04), residual volume (RV) (2.34 vs. -1.2, p < 0.0001), RV%TLC (total lung capacity) (2.63 vs. -0.72, p < 0.0001), and specific airway resistance (5.4 vs. 2.59, p = 0.04) were significantly higher in PTI patients as compared with controls (data were presented as median z-score). Air trapping was found in 60.0%, and abnormally high lung clearance index and DL_CO  were found in 73.3% and 90.9% of PTI patients, respectively.

CONCLUSIONS

This study demonstrated that lung function is affected in most children with PTI. PFTs showed that peripheral airways are the major zone of functional impairment.

The improved clinical course of persistent tachypnea of infancy with inhaled bronchodilators and corticosteroids

BACKGROUND

Persistent tachypnea of infancy (PTI) is the most common interstitial lung disease in young children. As no standardized therapeutic guidelines exist, different pharmaceuticals are used to treat PTI; inhaled corticosteroids (ICS) and bronchodilators being mostly used. This observation assessed the effectiveness of bronchodilators and ICS in children with PTI enrolled in the children's interstitial lung diseases (chILD)-EU Register.

METHODS

Symptomatic children with PTI were observed according to a predetermined stepwise protocol including bronchodilators as the first choice treatment (6 weeks). In patients with incomplete response, additionally, ICS was given (12 weeks). Signs, symptoms, and pulmonary function were evaluated at three time points: at baseline, 6 (±1) weeks after initiation of bronchodilators, and 12 (±1) weeks after bronchodilators/ICS.

RESULTS

Thirty-one children (median age: 44 months, interquartile range [IQR]: 15-67) were included. The therapy was associated with a significant reduction of tachypnea (53.3% of patients, p = 0.02), exercise intolerance (52.2% of patients, p < 0.001), chest retractions (43.8% of patients, p = 0.04), and crackles (29.2% of patients, p = 0.02). Also, a significant improvement in forced expiratory volume in 1 s (FEV₁ ) (median z score: -2.21 vs. -0.47, p = 0.03), residual volume (RV) (median z score 5.28 vs. 1.07, p = 0.007), RV% total lung capacity (TLC) (median z score: 6.05 vs. 1.48, p = 0.01), sRaw (median z score: 6.6 vs. 4.64, p = 0.01), R5 (median z score: 1.27 vs. 0.31, p = 0.009), and R5-R20 (median: 0.58 vs. 0.26 kPa/(l/s), p = 0.002) was demonstrated.

CONCLUSIONS

Inhaled bronchodilators and ICS may exert a positive effect on the severity of symptoms and pulmonary function test (PFT) in symptomatic children with PTI. However, a randomized control trial should be conducted to confirm their effectiveness.