ERS International Congress 2023: highlights from the Paediatrics Assembly.

Respiratory health in children is essential for general wellbeing and healthy development in the short and long term. It is well known that many respiratory diseases in adulthood have their origins in early life, and therefore research on prevention of respiratory diseases and management of children with respiratory diseases will benefit patients during the full life course. Scientific and clinical advances in the field of respiratory health are moving at a fast pace. This article summarises some of the highlights in paediatric respiratory medicine presented at the hybrid European Respiratory Society (ERS) International Congress 2023 which took place in Milan (Italy). Selected sessions are summarised by Early Career Members of the Paediatrics Assembly (Assembly 7) under the supervision of senior ERS officers, and cover a wide range of research areas in children, including respiratory physiology and sleep, asthma and allergy, cystic fibrosis, respiratory infection and immunology, neonatology and intensive care, respiratory epidemiology and bronchology.

Estimating pulmonary function after surgery for adolescent idiopathic scoliosis using biplanar radiographs of the chest with 3D reconstruction.

AIMS: This study addressed two questions: first, does surgical correction of an idiopathic scoliosis increase the volume of the rib cage, and second, is it possible to evaluate the change in lung function after corrective surgery for adolescent idiopathic scoliosis (AIS) using biplanar radiographs of the ribcage with 3D reconstruction? METHODS: A total of 45 patients with a thoracic AIS which needed surgical correction and fusion were included in a prospective study. All patients underwent pulmonary function testing (PFT) and low-dose biplanar radiographs both preoperatively and one year after surgery. The following measurements were recorded: forced vital capacity (FVC), slow vital capacity (SVC), and total lung capacity (TLC). Rib cage volume (RCV), maximum rib hump, main thoracic curve Cobb angle (MCCA), medial-lateral and anteroposterior diameter, and T4-T12 kyphosis were calculated from 3D reconstructions of the biplanar radiographs. RESULTS: All spinal and thoracic measurements improved significantly after surgery (p < 0.001). RCV increased from 4.9 l (SD 1) preoperatively to 5.3 l (SD 0.9) (p < 0.001) while TLC increased from 4.1 l (SD 0.9) preoperatively to 4.3 l (SD 0.8) (p < 0.001). RCV was correlated with all functional indexes before and after correction of the deformity. Improvement in RCV was weakly correlated with correction of the mean thoracic Cobb angle (p = 0.006). The difference in TLC was significantly correlated with changes in RCV (p = 0.041). It was possible to predict postoperative TLC from the postoperative RCV. CONCLUSION: 3D rib cage assessment from biplanar radiographs could be a minimally invasive method of estimating pulmonary function before and after spinal fusion in patients with an AIS. The 3D RCV reflects virtual chest capacity and hence pulmonary function in this group of patients. Cite this article: Bone Joint J 2022;104-B(1):112-119.

Peripheral obstruction without airflow limitation is rare and not specific to asthma in children.

Peripheral (or small) airway obstruction (PAO) is considered a marker of childhood asthma but the techniques able to directly measure it are rarely used in routine. Usual spirometry and plethysmography can detect a certain degree of PAO when reduced forced vital capacity (FVC) is associated to normal forced expiratory volume in 1 s (FEV1 ) to FVC ratio, and normal total lung capacity (TLC). The frequency of this functional pattern has never been studied in different pediatric respiratory conditions. To assess the prevalence and outcome of PAO in children with different diseases or symptoms, we retrospectively extracted from our database all files of Caucasian subjects encompassing spirometry and plethysmography measurements. Spirometry patterns (normal, airflow limitation [AFL; low FEV1 /FVC], low FVC [with normal FEV1 /FVC]) and final functional patterns (normal, AFL, PAO, restrictive [low TLC], or mixed) were described. We included 4394 files recorded in 1794 children (median [IQR] age: 10.7 [9.2-12.9] years). At inclusion, 125 (7%) children had low FVC of which 56 (44.8%, and 3.1% [95% CI 2.3-3.9] of the whole population) had PAO. PAO prevalence increased with age (OR (95% CI) per 2-year-increase: 2.26 (1.59-3.23); p < .001), and was more frequent in chronic bronchial diseases other than asthma (1.6% vs. 8.0%). On repeated tests, PAO frequently normalized (26.1%) or persisted (43.5%), but it less often progressed into AFL (13%) or restrictive (13%) patterns. PAO is an infrequent nonspecific and persistent functional pattern. Its prevalence increases with age and in diagnosis of chronic respiratory diseases other than asthma.

Severe central apnea secondary to cerebellar dysplasia in a child: look past Joubert syndrome.

NONE: We report the case of a female patient aged 12 years referred to our pediatric sleep unit with a history of central sleep apnea associated with transient episodes of tachypnea on polysomnography recordings. The patient was otherwise healthy, with no personal or family medical history, and had a normal physical and neuropsychological examination. Brain magnetic resonance imaging showed signs of cerebellar vermis dysplasia but without the classical features of the molar tooth sign. The rest of the workup (genetic tests, blood tests, cardiac investigations) was normal except for an increased peripheral chemosensitivity to carbon dioxide and oxygen. The patient was successfully treated with bilevel positive airway pressure. This case report highlights the importance of performing brain magnetic resonance imaging in patients with central sleep apnea to study the cerebellum, beyond the brainstem area. Cerebellar malformations can be found even in the absence of any other neurological condition.

TTC12 Loss-of-Function Mutations Cause Primary Ciliary Dyskinesia and Unveil Distinct Dynein Assembly Mechanisms in Motile Cilia Versus Flagella.

Cilia and flagella are evolutionarily conserved organelles whose motility relies on the outer and inner dynein arm complexes (ODAs and IDAs). Defects in ODAs and IDAs result in primary ciliary dyskinesia (PCD), a disease characterized by recurrent airway infections and male infertility. PCD mutations in assembly factors have been shown to cause a combined ODA-IDA defect, affecting both cilia and flagella. We identified four loss-of-function mutations in TTC12, which encodes a cytoplasmic protein, in four independent families in which affected individuals displayed a peculiar PCD phenotype characterized by the absence of ODAs and IDAs in sperm flagella, contrasting with the absence of only IDAs in respiratory cilia. Analyses of both primary cells from individuals carrying TTC12 mutations and human differentiated airway cells invalidated for TTC12 by a CRISPR-Cas9 approach revealed an IDA defect restricted to a subset of single-headed IDAs that are different in flagella and cilia, whereas TTC12 depletion in the ciliate Paramecium tetraurelia recapitulated the sperm phenotype. Overall, our study, which identifies TTC12 as a gene involved in PCD, unveils distinct dynein assembly mechanisms in human motile cilia versus flagella.

Associations of black carbon with lung function and airway inflammation in schoolchildren.

BACKGROUND: Few studies have investigated the 24-hour respiratory health effects of personal black carbon (BC) and ultrafine particles (UFP) exposure in schoolchildren. The objective of this study was to investigate these associations with the lung function in children 10-years old with and without persistent respiratory symptoms. METHODS: We conducted a cross-sectional study in 305 children (147 and 158 with and without persistent respiratory symptoms, respectively) from three European birth-cohorts: PARIS (France) and INMA Sabadell and Valencia (Spain). Personal 24-hour measurements of exposure concentrations to BC and UFP were performed by portable devices, before lung function testing. Forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and the fraction of exhaled nitric oxide (FeNO) were determined. RESULTS: There was no association of UFP with lung function parameters or FeNO whereas the increase in 24-hour BC exposure concentrations was related to a statistically significant decrease in lung function parameters only among children with persistent respiratory symptoms [-96.8 mL (95% Confidence Interval CI: -184.4 to -9.1 mL) in FVC, and -107.2 mL (95% CI: -177.5 to -36.9 mL) in FEV1 for an inter-quartile range of 1160 ng/m3 exposure increase]. A significant positive association between BC and FeNO was observed only in children with persistent respiratory symptoms with current wheezing and/or medication to improve breathing [FeNO increases with +6.9 ppb (95% CI: 0.7 to 13.1 ppb) with an inter-quartile range BC exposure increase]. CONCLUSION: Children suffering from persistent respiratory symptoms appear to be more vulnerable to BC exposure.

Gas exchanges in children with cystic fibrosis or primary ciliary dyskinesia: A retrospective study.

Primary ciliary dyskinesia (PCD) and cystic fibrosis (CF) both entail bronchiectasis and pulmonary impairment as measured using spirometry, during childhood. We aimed at looking whether blood gas exchanges progressed differently between CF and PCD children in a retrospective study of repeated measurements. Comparisons between groups (Wilcoxon-Mann-Whitney and Chi-squared tests) and a mixed linear model, adjusted for age, evaluated associations between diseases and PaO2, PaCO2, or PaO2-PaCO2 ratio. Among 42 PCD and 73 CF children, 62% and 59% had respectively bronchiectasis (P = 0.75). Spirometry and blood gases were similar at inclusion (PaO2 median [IQR] PCD -1.80 [-3.40; -0.40]; CF -1.80 [-4.20; 0.60] z-scores; P = 0.72). PaO2 and PaO2-PaCO2 ratio similarly and significantly decreased with age in both groups (P < 0.01) whereas PaCO2 increased more in CF (P = 0.02) remaining within the range of normal (except for one child). To conclude, gas exchange characteristics, similarly initially impaired in PCD and CF children, tended to less deteriorate with time in PCD children who could benefit from an early diagnosis.

Airway Remodeling in Preschool Children with Severe Recurrent Wheeze.

RATIONALE: Airway wall structure in preschoolers with severe recurrent wheeze is poorly described. OBJECTIVES: To describe airway wall structure and inflammation in preschoolers with severe recurrent wheeze. METHODS: Flexible bronchoscopy was performed in two groups of preschoolers with severe recurrent wheeze: group 1, less than or equal to 36 months (n = 20); group 2, 36-59 months (n = 29). We assessed airway inflammation, reticular basement membrane (RBM) thickness, airway smooth muscle (ASM), mucus gland area, vascularity, and epithelial integrity. Comparisons were then made with biopsies from 21 previously described schoolchildren with severe asthma (group 3, 5-11.2 yr). MEASUREMENTS AND MAIN RESULTS: RBM thickness was lower in group 1 than in group 2 (3.3 vs. 3.9 µm; P = 0.02), was correlated with age (P < 0.01; ρ = 0.62), and was higher in schoolchildren than in preschoolers (6.8 vs. 3.8 µm; P < 0.01). ASM area was lower in preschoolers than in schoolchildren (9.8% vs. 16.5%; P < 0.01). Vascularity was higher in group 1 than in group 2 (P = 0.02) and group 3 (P < 0.05). Mucus gland area was higher in preschoolers than in schoolchildren (16.4% vs. 4.6%; P < 0.01). Inflammatory cell counts in biopsies were not correlated with airway wall structure. ASM area was higher in preschoolers with atopy than without atopy (13.1% vs. 7.7%; P = 0.01). Airway morphometrics and inflammation were similar in viral and multiple-trigger wheezers. CONCLUSIONS: In preschoolers with severe recurrent wheeze, markers of remodeling and inflammation are unrelated, and atopy is associated with ASM. In the absence of control subjects, we cannot determine whether differences observed in RBM thickness and vascularity result from disease or normal age-related development.

Sleep disordered breathing in patients with Prader-Willi syndrome: A multicenter study.

OBJECTIVES: Sleep disordered breathing (SDB) is common in patients with Prader-Willi syndrome (PWS) and systematic screening is recommended, especially before growth hormone treatment. The aim of the study was to describe the baseline SDB and therapeutic interventions in a large cohort of patients. STUDY DESIGN: Retrospective study. SUBJECT SELECTION: Eighty-eight patients with PWS, median [interquartile range] age of 5.1 [1.0-14.5] years old (range 0.3-44.3), who were followed in three centers (France, Italy). METHODOLOGY: Anthropometrics, polygraphy (PG), and gas exchange data were analyzed. RESULTS: Median body mass index (BMI) was 20 [16-34] kg/m(2), BMI z-score for patients aged 2-20 years old was 2.1 [1.2-2.8] SD, mixed-obstructive apnea-hypopnea index (MOAHI) 1.8 [0.6-5.0] events/hr, and central apnea index (CAI) 0.1 [0.0-0.6] events/hr. Minimum pulse oximetry (SpO2) was 88 [84-91]%, percentage of time with SpO2 <90% 0.1 [0.0-1.0]%, and oxygen desaturation index 2 [1-4]/hr. An apnea-hypopnea index (AHI) ≥ 1.5 and ≥ 5 events/hr was observed in 53% of children and 41% of adults, respectively. No correlations were observed between MOAHI and anthropometrics data (age, BMI, BMI z-score), while MOAHI significantly correlated with SpO2 indexes. Age and BMI only weakly correlated with SpO2 indexes. Growth hormone could be initiated in 48 patients. Regarding post-PG therapy, 9 patients had upper airway surgery, and noninvasive CPAP/bilevel ventilation was started in 16 patients. CONCLUSIONS: Patients with PWS exhibit a high prevalence of SDB. The lack of association between obesity and SDB leads to hypothesize that hypotonia and/or facial dysmorphic features may play a major role in the occurrence of SDB.

Loss-of-function mutations in RSPH1 cause primary ciliary dyskinesia with central-complex and radial-spoke defects.

Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive respiratory disorder resulting from defects of motile cilia. Various axonemal ultrastructural phenotypes have been observed, including one with so-called central-complex (CC) defects, whose molecular basis remains unexplained in most cases. To identify genes involved in this phenotype, whose diagnosis can be particularly difficult to establish, we combined homozygosity mapping and whole-exome sequencing in a consanguineous individual with CC defects. This identified a nonsense mutation in RSPH1, a gene whose ortholog in Chlamydomonas reinhardtii encodes a radial-spoke (RS)-head protein and is mainly expressed in respiratory and testis cells. Subsequent analyses of RSPH1 identified biallelic mutations in 10 of 48 independent families affected by CC defects. These mutations include splicing defects, as demonstrated by the study of RSPH1 transcripts obtained from airway cells of affected individuals. Wild-type RSPH1 localizes within cilia of airway cells, but we were unable to detect it in an individual with RSPH1 loss-of-function mutations. High-speed-videomicroscopy analyses revealed the coexistence of different ciliary beating patterns-cilia with a normal beat frequency but abnormal motion alongside immotile cilia or cilia with a slowed beat frequency-in each individual. This study shows that this gene is mutated in 20.8% of individuals with CC defects, whose diagnosis could now be improved by molecular screening. RSPH1 mutations thus appear as a major etiology for this PCD phenotype, which in fact includes RS defects, thereby unveiling the importance of RSPH1 in the proper building of CCs and RSs in humans.

An official American Thoracic Society workshop report: optimal lung function tests for monitoring cystic fibrosis, bronchopulmonary dysplasia, and recurrent wheezing in children less than 6 years of age.

Although pulmonary function testing plays a key role in the diagnosis and management of chronic pulmonary conditions in children under 6 years of age, objective physiologic assessment is limited in the clinical care of infants and children less than 6 years old, due to the challenges of measuring lung function in this age range. Ongoing research in lung function testing in infants, toddlers, and preschoolers has resulted in techniques that show promise as safe, feasible, and potentially clinically useful tests. Official American Thoracic Society workshops were convened in 2009 and 2010 to review six lung function tests based on a comprehensive review of the literature (infant raised-volume rapid thoracic compression and plethysmography, preschool spirometry, specific airway resistance, forced oscillation, the interrupter technique, and multiple-breath washout). In these proceedings, the current state of the art for each of these tests is reviewed as it applies to the clinical management of infants and children under 6 years of age with cystic fibrosis, bronchopulmonary dysplasia, and recurrent wheeze, using a standardized format that allows easy comparison between the measures. Although insufficient evidence exists to recommend incorporation of these tests into the routine diagnostic evaluation and clinical monitoring of infants and young children with cystic fibrosis, bronchopulmonary dysplasia, or recurrent wheeze, they may be valuable tools with which to address specific concerns, such as ongoing symptoms or monitoring response to treatment, and as outcome measures in clinical research studies.

Primary ciliary dyskinesia presentation in 60 children according to ciliary ultrastructure.

Primary ciliary dyskinesia (PCD) is an inherited disease related to ciliary dysfunction, with heterogeneity in clinical presentation and in ciliary ultrastructural defect. Our study intended to determine if there are phenotypic differences in patients with PCD based on ciliary ultrastructural abnormality. In this retrospective study carried out among 60 children with a definitive diagnosis of PCD, we analyzed clinical, radiological, and functional features at diagnosis and at last recorded visit, according to cilia defect (absence of dynein arms: DAD group, n = 36; abnormalities of the central complex: CCA group, n = 24). Onset of respiratory symptoms occurred later in the CCA than in the DAD group (9.5 versus 0.5 months, p = 0.03). Situs inversus was only observed in the DAD group, while respiratory disease in siblings were more frequent in the CCA group (p = 0.003). At diagnosis, clinical presentation was more severe in the CCA group: frequency of respiratory tract infections (p = 0.008), rhinosinusitis (p = 0.02), otitis complications (p = 0.0001), bilateral bronchiectasis (p = 0.04), and number of hypoxemic patients (p = 0.03). Pulmonary function remained stable in both groups, but outcome was better in the CCA than in the DAD group: less antibiotic therapy and hypoxemic patients (p = 0.004). In conclusion, our results underlined the relationship between the severity of clinical presentation and the ultrastructural ciliary defect.

Comparison between US and MRI in the prenatal assessment of lung malformations.

BACKGROUND: The contribution of MRI in the prenatal evaluation of congenital lung abnormalities (CLA) has not been extensively investigated. OBJECTIVE: (1) To compare diagnostic accuracy and assessment of prognostic factors between US and MRI in CLA and (2) to assess the diagnosis agreement between prenatal imaging and postnatal diagnosis. MATERIALS AND METHODS: We included 23 consecutive fetuses who underwent concomitant US and MRI during gestation as well as postnatal CT and surgery (n = 22). RESULTS: US-MRI sets were performed at median gestational age of 26 (n = 16) and 34 (n = 22) weeks. Postnatal diagnoses were 11 congenital pulmonary airway malformations (CPAM), 4 bronchopulmonary sequestrations (BPS), 6 hybrid lesions and 2 cysts. US and MRI agreement was significantly better during the second trimester than during the third one (P = 0.02). Disagreements were related to missed cysts (n = 5), mediastinal shift (n = 6) and vessels (n = 5). US and MRI diagnosis agreement was present in 20 cases, including 5 cases of misdiagnosis. US and MRI were concordant with postnatal diagnosis in 17 and 16 cases, respectively. CONCLUSION: In our series, no clear superiority of MRI over US in the prenatal evaluation of CLA was demonstrated, but US better demonstrated systemic feeding vessels and MRI cysts and normal lung adjacent to the lesion.

[Quality of life, asthma control, urinary cotinine and therapeutic education among asthmatic children]. / Qualité de vie, contrôle de l'asthme, cotininurie et éducation thérapeutique de l'enfant asthmatique.

Therapeutic patient education (TPE) has been standard practice in France for roughly 20 years. However, TPE has only recently been officially recognized and has rarely been assessed. The objective of this study was to assess the impact of TPE on passive smoking exposure and asthma outcomes in young patients referred to a hospital school for children with asthma. A prospective cohort study was conducted to determine the socio-economic status, environmental exposure (including parental tobacco consumption) and medical history of children starting out on a TPE course. The study measured quality of life and urinary cotinine. Asthma control was also assessed. Out of a total of 54 children (median age 8.6 years), 35 and 26 children attended three or at least four TPE sessions, respectively. Uncontrolled asthma and a history of hospitalization for exacerbation of asthma were frequent (43% and 61%, respectively). In utero passive smoke exposure was more frequent in the hospitalization group (p = 0.07). Urinary cotinine levels were similar in children exposed and not exposed to tobacco smoke (259 vs 141 nMol.L-1, p = 0.15), but only decreased in the group of exposed children. In 34 children, quality of life improved significantly between the first and the third or fourth sessions (n = 23, median increase 1.06, p = 0.1), while asthma control improved in 64% of the patients (n = 33, p = 0.01) and emergency attendances decreased (n = 34, p = 0.001). The positive effects of TPE on asthma control and quality of life were quickly visible but did not prevent children from withdrawing from the program. Urinary cotinine was not useful for detecting exposure to tobacco smoke, but may be useful as an indicator of exposure to tobacco smoke. The results indicate an improvement in quality of life and asthma control as TPE proceeded.

Delineation of CCDC39/CCDC40 mutation spectrum and associated phenotypes in primary ciliary dyskinesia.

BACKGROUND: CCDC39 and CCDC40 genes have recently been implicated in primary ciliary dyskinesia (PCD) with inner dynein arm (IDA) defects and axonemal disorganisation; their contribution to the disease is, however, unknown. Aiming to delineate the CCDC39/CCDC40 mutation spectrum and associated phenotypes, this study screened a large cohort of patients with IDA defects, in whom clinical and ciliary phenotypes were accurately described. METHODS: All CCDC39 and CCDC40 exons and intronic boundaries were sequenced in 43 patients from 40 unrelated families. The study recorded and compared clinical features (sex, origin, consanguinity, laterality defects, ages at first symptoms and at phenotype evaluation, neonatal respiratory distress, airway infections, nasal polyposis, otitis media, bronchiectasis, infertility), ciliary beat frequency, and quantitative ultrastructural analyses of cilia and sperm flagella. RESULTS: Biallelic CCDC39 or CCDC40 mutations were identified in 30/34 (88.2%) unrelated families with IDA defects associated with axonemal disorganisation (22 and eight families, respectively). Fourteen of the 28 identified mutations are novel. No mutation was found in the six families with isolated IDA defects. Patients with identified mutations shared a similar phenotype, in terms of both clinical features and ciliary structure and function. The sperm flagellar ultrastructure, analysed in 4/7 infertile males, showed evidence of abnormalities similar to the ciliary ones. CONCLUSIONS: CCDC39 and CCDC40 mutations represent the major cause of PCD with IDA defects and axonemal disorganisation. Patients carrying CCDC39 or CCDC40 mutations are phenotypically indistinguishable. CCDC39 and CCDC40 analyses in selected patients ensure mutations are found with high probability, even if clinical or ciliary phenotypes cannot prioritise one analysis over the other.

Lung function, diagnosis, and treatment of sleep-disordered breathing in children with achondroplasia.

Children with achondroplasia are at risk of sleep-disordered breathing. The aim of the study was to evaluate lung function and sleep-disordered breathing in children with achondroplasia. An interview, clinical examination, lung function tests with blood gases, and a polygraphic sleep study were obtained as part of routine annual evaluation in consecutive children with achondroplasia. We included 30 children (median age 3.0 years, range: 0.4-17.1) over a period of 21 months. Habitual snoring and witnessed apneas were observed in 77% and 33% of the patients, respectively. Prior to the sleep study, 10/29 (34%) patients had undergone upper airway surgery and 5/29 (17%) craniocervical decompression operation. Arterial blood gases were abnormal in two (7%) patients. Sleep findings were abnormal in 28/30 (93%) patients. Eleven (37%) patients had an apnea index≥1 event/hr and 26 (87%) had an apnea-hypopnea index≥5 events/hr. The ≥3% desaturation index was >5/hr in 22 (73%) patients. Sixteen (53%) patients had a minimal pulse oximetry<90% but only two (7%) patients had a maximal transcutaneous carbon dioxide pressure>50 mmHg during sleep. As a consequence, the following therapeutic interventions were performed: upper airway surgery in four patients and noninvasive positive pressure ventilation (NPPV) in five other patients, resulting in an improvement in sleep studies in all nine patients. Systematic sleep studies are recommended in children with achondroplasia because of the high prevalence of sleep-disordered breathing. Upper airway surgery and NPPV are effective treatments of sleep-disordered breathing.

CCDC39 is required for assembly of inner dynein arms and the dynein regulatory complex and for normal ciliary motility in humans and dogs.

Primary ciliary dyskinesia (PCD) is an inherited disorder characterized by recurrent infections of the upper and lower respiratory tract, reduced fertility in males and situs inversus in about 50% of affected individuals (Kartagener syndrome). It is caused by motility defects in the respiratory cilia that are responsible for airway clearance, the flagella that propel sperm cells and the nodal monocilia that determine left-right asymmetry. Recessive mutations that cause PCD have been identified in genes encoding components of the outer dynein arms, radial spokes and cytoplasmic pre-assembly factors of axonemal dyneins, but these mutations account for only about 50% of cases of PCD. We exploited the unique properties of dog populations to positionally clone a new PCD gene, CCDC39. We found that loss-of-function mutations in the human ortholog underlie a substantial fraction of PCD cases with axonemal disorganization and abnormal ciliary beating. Functional analyses indicated that CCDC39 localizes to ciliary axonemes and is essential for assembly of inner dynein arms and the dynein regulatory complex.

Gas trapping is associated with severe exacerbation in asthmatic children.

BACKGROUND: Gas trapping suggesting small airway disease is observed in adult asthmatic suffering from severe asthma. The aim of the study was to assess whether gas trapping could be evidenced in asthmatic children with/without severe exacerbation and with/without symptoms during the past three months. METHODS AND PATIENTS: Forced expiratory flows (FEV(1), FVC, MEF(25-75%), MEF(50%)), plethysmographic lung volumes (TLC, FRC, RV) before and after bronchodilation (BD) were recorded in asthmatic children with documented airflow reversibility. Three groups were defined according to the presence during the last three months of 1) severe exacerbation (oral steroid: 3 consecutive days) 2) asthma symptoms without severe exacerbation and 3) without any symptom (GINA guidelines). RESULTS: 180 children (median 11.3 years, range 6.3-17.6, 57 girls) were included, 24 (13%) had at least one severe exacerbation, 58 (33%) had respiratory symptoms without severe exacerbation and 98 (54%) had no symptom during the past 3 months. Forced expiratory flows did not significantly differ in these three groups, while RV/TLC was significantly higher in the first group before and even after bronchodilation: before BD, 0.27 +/- 0.07, 0.24 +/- 0.05 and 0.23 +/- 0.05, respectively (p = 0.016) and after BD, 0.25 +/- 0.07, 0.21 +/- 0.05, 0.21 +/- 0.05, respectively (p = 0.003). CONCLUSION: In asthmatic children, gas trapping is associated with occurrence of a severe exacerbation during the last three months, suggesting a small airway disease that is not evidenced by forced expiratory flows.