Hyperoxic ventilatory response in infants is related to nocturnal hypoxaemia.

Background: The carotid bodies primarily serve as oxaemia sensors that affect tidal breathing. Their function has not yet been studied in infants with nocturnal hypoxaemia. This cross-sectional study aimed to characterise the hyperoxic ventilatory response (HVR) in infants and its relationship to nocturnal hypoxaemia. Methods: The HVR was analysed in term infants aged <24 months with childhood interstitial lung disease (chILD), those with severe recurrent wheezing (wheeze), and nonrespiratory controls. The HVR timing was characterised using hyperoxia response time (HRT1), and HVR magnitude was characterised by the relative change in minute volume between normoxia and 30-s hyperoxia (VE_dH30). Time spent with an arterial haemoglobin oxygen saturation (SpO2) <90% during overnight monitoring (t90) was estimated. Results: HVR data were available for 23 infants with chILD, 24 wheeze and 14 control infants. A significant decrease in minute volume under 30 s of hyperoxia was observed in all patients. HRT1 was shorter in chILD (5.6±1.2 s) and wheeze (5.9±1.5 s) groups than in the controls (12.6±5.5 s) (ANOVA p<0.001). VE_dH30 was increased in the chILD group (24.3±8.0%) compared with that in the controls (14.7±9.2%) (p=0.003). t90 was abnormal in the wheeze (8.0±5.0%) and chILD (32.7±25.8%) groups and higher in the chILD group than in the controls (p<0.001). HRT1 negatively correlated with t90 in all groups. Conclusion: Significant differences in HVR timing and magnitude were noted in the chILD, wheeze and control groups. A relationship between nocturnal hypoxaemia and HRT1 was proposed. HVR characterisation may help identify patients with abnormal nocturnal SpO2.

Baseline reticular basement membrane morphology is related to subsequent spirometry deterioration in pediatric chronic airway inflammation: a follow-up study.

Reticular basement membrane (RBM) thickening may occur in children with allergic bronchial asthma (BA), cystic fibrosis (CF), and primary ciliary dyskinesia (PCD). Its functional consequences remain unknown. We investigated the relationship between baseline RBM thickness and subsequent spirometry. In our cohort follow-up study, patients aged 3-18 yr with BA, CF, and PCD and controls underwent baseline lung clearance index (LCI) measurement, spirometry, and endobronchial biopsy sampling. Total RBM and collagen IV-positive layer thickness were measured. Trends in forced vital capacity (FVC), forced expired volume in 1 s (FEV1), and FEV1/FVC were analyzed during follow-up, and their relationship to baseline characteristics was studied using univariate analysis and multiple regression models. Complete baseline data were available in 19 patients with BA, 30 patients with CF, 25 patients with PCD, and 19 controls. The RBM was thicker in patients with BA (6.33 ± 1.22 µm), CF (5.60 ± 1.39 µm), and PCD (6.50 ± 1.87 µm) than in controls (3.29 ± 0.55 µm) (all P < 0.001). The LCI was higher in patients with CF (15.32 ± 4.58, P < 0.001) and PCD (10.97 ± 2.46, P = 0.002) than in controls (7.44 ± 0.43). The median follow-up times were 3.6, 4.8, 5.7, and 1.9 years in patients with BA, CF, PCD, and controls, respectively. The z-scores of FEV1 and FEV1/FVC deteriorated significantly in all groups except in controls. In patients with CF and PCD, trends in FEV1 z-scores correlated with baseline LCI and RBM; in BA, it correlated with collagen IV. In multiple regression models, RBM morphology and ventilation inhomogeneity could predict up to 84.4% of variability in spirometry trends. In conclusion, baseline LCI value and RBM morphology may predict trends in subsequent spirometry.NEW & NOTEWORTHY This paper deals with the relationship between reticular basement membrane (RBM) morphology at baseline and follow-up spirometry in children with asthma, cystic fibrosis, and primary ciliary dyskinesia. For the first time, to our knowledge, the possibility to predict subsequent lung function development using selected baseline characteristics (reticular basement membrane morphology from endobronchial biopsy and ventilation inhomogeneity from nitrogen multiple breath washout test) is proposed. Corresponding predictive models are presented.

Symptomatic preterm infants suffer from lung function deficits, regardless of bronchopulmonary dysplasia.

BACKGROUND: The long-term respiratory consequences for children with bronchopulmonary dysplasia (BPD) are well known. However, there is little emphasis on monitoring preterm infants without BPD. Few studies have explored the lung function status of infants with the symptoms of chronic lung disease of prematurity (CLD). OBJECTIVE: To evaluate functional lung deficits in preterm infants with CLD, and to assess the perinatal determinants of diminished lung function. METHODS: In our cross-sectional study, 132 preterm infants with symptomatic CLD underwent infant pulmonary function testing (iPFT) at a median post-term age of 0.9 years. The iPFT included bodypletysmography, compliance measurement, tidal breath analysis, and rapid thoracoabdominal compression. The relationships between the respective z scores of the iPFT parameters and perinatal characteristics, postnatal treatment, and BPD status were investigated. RESULTS: Seventy-three patients (55.3%) were born before the 28th week of gestation, and 92 (69.7%) met the BPD criteria. Functional deficits were detected in 85.8%. The obstructive ventilatory pattern was more prevalent than restrictive (36.3 vs. 12.4%, p < 0.001). Infants with restriction had lower birth weight (BW) and required a longer duration of oxygenotherapy. In a univariate model, the lung function correlated with the duration of invasive mechanical ventilation, gestational week, and BW. In a general linear model, BPD status was not an additional determinant of the iPFT results. CONCLUSION: IPFT may reveal significant functional deficits in preterm infants with CLD even without BPD. The current symptoms and perinatal factors may be more important determinants of functional deficits than the BPD status itself.

Repeatability of lung clearance index in infants with cystic fibrosis and recurrent wheeze.

OBJECTIVES: To describe the short- and medium-term repeatability of lung clearance index at 2.5% (LCI2.5 ) in infants and calculate the number of patients needed to enroll in a study (N) using LCI2.5 as a primary outcome. METHODS: An 8-month follow-up observational study was employed for assessing short-term [coefficient of repeatability (CR) and intraclass correlation (ICC)] and medium-term repeatability (Bland-Altman method) of LCI2.5 in infants with cystic fibrosis (CF) or recurrent wheeze (RW) measured by the nitrogen multiple-breath washout test (N2 -MBW). Using these variability data, the N to reach 90% test power at the level of statistical significance (0.05) was calculated. RESULTS: Forty infants with CF and 21 with RW were enrolled. Initial N2 -MBW testing was successful in 33 and 17 patients, respectively. Follow-up data were available for 23 and 11 infants, respectively. Short-term repeatability of LCI2.5 was high (CR = 1.10 and 1.04 in CF and RW patients, respectively; ICC = 0.88 and 0.83 in CF and RW patients, respectively). The between-subject standard deviation was <13% of the actual LCI2.5 value. In clinically stable patients, LCI2.5 did not significantly change during the 8-month follow-up. Mean LCI2.5 change was -0.08 (1% of baseline) in CF and -0.05 (0.6%) in RW, with 95% limits of agreement being (-1.70; 1.53) in CF and (-1.51; 1.40) in RW patients. N = 23 infants if both intragroup differences of LCI2.5 and minimal difference to be detected would be 2.0. CONCLUSION: N2 -MBW may be a reproducible tool with reasonable test power to detect differences in infant studies.

Lung Resection in Children with Necrotizing Pneumonia: Outcome and Follow-up.

INTRODUCTION: The number of patients with necrotizing pneumonia has increased in recent years. The aim of this study is to review the incidence, management, and outcome of pediatric necrotizing pneumonia requiring surgical therapy and to prove that lung resection results in favorable development of patients. We hypothesize that overall lung function in children after lung resection does not differ from that of the healthy population. MATERIALS AND METHODS: A retrospective tertiary referral center study with a prospective follow-up spirometric study of patients with necrotizing pneumonia managed between January 2010 and December 2019 was performed. RESULTS: The study cohort consisted of 1,295 patients admitted to the pediatric department for community-acquired pneumonia; 47 patients developed necrotizing pneumonia, 36 of whom underwent parenchymal lung resection. A 5-year rise in the occurrence of necrotizing pneumonia requiring resection was 77%, with a significant increase in the last 3 years (p < 0.05). The median age at the time of surgery was 32.5 (interquartile range [IQR]: 32.25) months. Streptococcus pneumoniae was the most prevalent pathogen (83%), although 53.3% of these patients were vaccinated against the agent. In 67% of patients, preresection procedures were performed: drainage of pneumothorax (17%), drainage of empyema (46%), drainage of empyema with use of alteplase (25%), and thoracoscopic decortication (12%). Surgical procedures included lobectomy (72.2%), wedge resection (13.9%), bilobectomy (8.3%), and pneumonectomy (5.6%). The postoperative complication was bronchopleural fistula in three patients. There were two (5.5%) postoperative deaths due to multiple organ failure. The follow-up spirometry was performed 43.3 (median, IQR 23.8-66.7) months after surgical intervention. Normal lung function was detected in 35 (64.8%) patients, restrictive pattern in 6 (11.1%) patients, obstructive pattern in 11 (20.4%) patients, and combined in 2 (3.7%) patients. CONCLUSION: The number of patients with necrotizing pneumonia requiring resection has increased significantly in the last 3 years (p < 0.05). Aggressive surgical treatment results in significant clinical improvement in most cases and favorable lung function outcome. Long-term follow-up showed normal spirometry in 64.8% of cases.

Evaluation of a Clinical Index as a Predictive Tool for Primary Ciliary Dyskinesia.

BACKGROUND: In primary ciliary dyskinesia (PCD) there is no single diagnostic test. Different predictive tools have been proposed to guide referral of high-risk patients for further diagnostic workup. We aimed to test clinical index (CI) on a large unselected cohort and compare its characteristics with other widely used tools-PICADAR and NA-CDCF. METHODS: CI, PICADAR, and NA-CDCF scores were calculated in 1401 patients with suspected PCD referred to our center. Their predictive characteristics were analyzed using receiver operating characteristics (ROC) curves and compared to each other. Nasal nitric oxide (nNO) was measured in 569 patients older than 3 years. RESULTS: PCD was diagnosed in 67 (4.8%) patients. CI, PICADAR, and NA-CDCF scores were higher in PCD than in nonPCD group (all p < 0.001). The area under the ROC curve (AUC) for CI was larger than for NA-CDCF (p = 0.005); AUCPICADAR and AUCNA-CDCF did not differ (p = 0.093). An overlap in signs and symptoms among tools was identified. PICADAR could not be assessed in 86 (6.1%) patients without chronic wet cough. For CI laterality or congenital heart defects assessment was not necessary. nNO further improved predictive power of all three tools. CONCLUSION: CI is a feasible predictive tool for PCD that may outperform PICADAR and NA-CFCD.

Transition of patients with interstitial lung disease from paediatric to adult care.

The European Cooperation in Science and Technology (COST) is a funding organisation for the creation of research networks, called COST Actions. COST Action 16125 was dedicated to European network for translational research in children's and adult interstitial lung disease. Working Group 5 of the COST Action CA16125 focussed on the problems of transition of children with interstitial lung diseases from paediatric to adult care. Results of this survey performed among members of the Working Group and some affiliated specialists showed highly variable and inadequate current system of transitions of these patients to adult care in most centres. In most centres there is no established and consistent procedure to guarantee appropriate transfer of information and prepare the patient for transition to a new specialist and a new team. Immediate action is therefore required. The Working Group has prepared a model procedure for the transition, based on protocols from several centres with established pathways, either for childhood interstitial lung disease or other chronic respiratory diseases.

Reflex zone stimulation reduces ventilation inhomogeneity in cystic fibrosis: A randomised controlled cross-over study.

BACKGROUND: The reflex zone stimulation technique (RST) activates complex motor responses and has a positive impact on the locomotor system. This technique may also indirectly affect breathing; however, the use of this technique as adjunct of the treatment of cystic fibrosis (CF) has not yet been characterised. METHODS: We performed a randomised controlled single-centre interventional trial to evaluate the short-term effects of RST on lung function in 21 paediatric CF patients with normal baseline spirometry. The effect of 30 min of RST was compared to that of sham therapy in a crossover design. The interventions were performed in random order and planned 6 months apart. The primary outcome was a change in global ventilation inhomogeneity after intervention, assessed by lung clearance index (LCI2.5 ) derived from a nitrogen multiple breath washout test. Secondary outcomes included changes in regional ventilation inhomogeneity (indices of acinar [Sacin*Vt] and conductive airway [Scond*Vt] inhomogeneity) and spirometry parameters (inspiratory capacity, forced vital capacity, and forced expiratory volume in 1 s). Trunk deformity was assessed by physiotherapists at study entry. RESULTS: After the RST intervention, the LCI2.5 (p = .004) and Scond*Vt (p = .009) decreased significantly, while inspiratory capacity increased (p = .012). In the sham-therapy group, none of the parameters changed significantly. Trunk deformity was seen in 76.5% of all patients, and 92.9% of those with trunk deformity showed a decrease in LCI2.5 after RST. CONCLUSION: RST has multiple positive short-term effects on lung function, especially in CF patients with trunk deformities.

Pulmonary function testing in children's interstitial lung disease.

The use of pulmonary function tests (PFTs) has been widely described in airway diseases like asthma and cystic fibrosis, but for children's interstitial lung disease (chILD), which encompasses a broad spectrum of pathologies, the usefulness of PFTs is still undetermined, despite widespread use in adult interstitial lung disease. A literature review was initiated by the COST/Enter chILD working group aiming to describe published studies, to identify gaps in knowledge and to propose future research goals in regard to spirometry, whole-body plethysmography, infant and pre-school PFTs, measurement of diffusing capacity, multiple breath washout and cardiopulmonary exercise tests in chILD. The search revealed a limited number of papers published in the past three decades, of which the majority were descriptive and did not report pulmonary function as the main outcome.PFTs may be useful in different stages of management of children with suspected or confirmed chILD, but the chILD spectrum is diverse and includes a heterogeneous patient group in all ages. Research studies in well-defined patient cohorts are needed to establish which PFT and outcomes are most relevant for diagnosis, evaluation of disease severity and course, and monitoring individual conditions both for improvement in clinical care and as end-points in future randomised controlled trials.

Ventilation Inhomogeneity and Bronchial Basement Membrane Changes in Chronic Neutrophilic Airway Inflammation.

BACKGROUND: Bronchial epithelial reticular basement membrane (RBM) thickening occurs in diseases with both eosinophilic (allergic bronchial asthma [BA]) and neutrophilic (cystic fibrosis [CF] and primary ciliary dyskinesia [PCD]) chronic airway inflammation; however, the lung function and airway remodeling relation remains unclear. The aim of this study was to test whether ventilation inhomogeneity is related to RBM thickening. METHODS: Multiple breath washout test, endobronchial biopsy, and BAL were performed in 24 children with CF, 11 with PCD, 15 with BA, and in 19 control subjects. Lung clearance index at 2.5% (1/40th) of starting nitrogen concentration (LCI2.5), RBM thickness, and lavage fluid cytology were quantified; their mutual associations were studied by using Spearman rank correlations (r). RESULTS: In asthma, ventilation inhomogeneity (mean ± SD) was mild (LCI2.5, 9.3 ± 1.4 vs 7.9 ± 0.9 in control subjects; P = .0391), and the RBM thickened (5.26 ± 0.98 µm vs 3.12 ± 0.62 µm in control subjects; P < .0001). No relation between RBM thickness and ventilation inhomogeneity or lavage cytology was found. In CF and PCD, RBM thickness was similar to that in asthma (4.54 ± 0.66 µm and 5.27 ± 1.11 µm, respectively), but ventilation inhomogeneity was significantly higher (LCI2.5, 12.5 ± 2.4 and 11.8 ± 2.5). Both in CF and PCD, RBM thickness correlated with LCI2.5 (r = 0.594, P = .015; r = 0.821, P = .023). In PCD only, RBM thickness was also related to the number of neutrophils in lavage fluid (r = 0.821; P = .023). CONCLUSIONS: Lung function impairment in relation to RBM thickness was milder in BA than in CF and PCD. In asthma, ventilation inhomogeneity did not correlate with RBM thickness, whereas it did in CF and PCD. This outcome suggests a different structure-function relation in these diseases.

Novel approach to computerized breath detection in lung function diagnostics.

BACKGROUND: Breath detection, i.e. its precise delineation in time is a crucial step in lung function data analysis as obtaining any clinically relevant index is based on the proper localization of breath ends. Current threshold or smoothing algorithms suffer from severe inaccuracy in cases of suboptimal data quality. Especially in infants, the precise analysis is of utmost importance. The key objective of our work is to design an algorithm for accurate breath detection in severely distorted data. METHODS: Flow and gas concentration data from multiple breath washout test were the input information. Based on universal physiological characteristics of the respiratory tract we designed an algorithm for breath detection. Its accuracy was tested on severely distorted data from 19 patients with different types of breathing disorders. Its performance was compared to the performance of currently used algorithms and to the breath counts estimated by human experts. RESULTS: The novel algorithm outperformed the threshold algorithms with respect to their accuracy and had similar performance to human experts. It proved to be a highly robust and efficient approach in severely distorted data. This was demonstrated on patients with different pulmonary disorders. CONCLUSION: Our newly proposed algorithm is highly robust and universal. It works accurately even on severely distorted data, where the other tested algorithms failed. It does not require any pre-set thresholds or other patient-specific inputs. Consequently, it may be used with a broad spectrum of patients. It has the potential to replace current approaches to the breath detection in pulmonary function diagnostics.