Update in pediatric lung disease 2013

A juvenile murine model with chronic lung inflammation induced by repeated intratracheal instillation of lipopolysaccharides: a versatile and replicable model

BACKGROUND

Recurrent lower respiratory tract infection or chronic pulmonary infection often occur in children with chronic lung diseases (CLDs). By continuous lung inflammation, recurrent and chronic infection could cause irreversible airway structural and lung function damage, which eventually leads to respiratory failure and death.

METHODS

In purpose of recapitulating persistent high-intensity lung inflammation caused by recurrent lower respiratory tract infection or chronic infection, we established a juvenile murine model with chronic lung inflammation induced by repeated intratracheal instillations of lipopolysaccharides (LPS) from Pseudomonas aeruginosa once a week for 4 weeks. Four-week-old C57BL/6N mice were divided into 4 groups, including LPS_0.5 group (n=15), LPS_1.0 group (n=15), Control group (n=15) and Normal group (n=15). Mice in LPS_0.5 group and LPS_1.0 group were instilled intratracheally with 0.5 mg/kg LPS and 1.0 mg/kg LPS respectively. Mice in control group were instilled intratracheally with LPS-free sterile 0.9% NaCl, whereas normal group received no treatment. The successful chronic lung inflammation murine model was validated via (I) pathological manifestations of chronic inflammatory mononuclear-cell infiltration and lung parenchyma damage; (II) decreased lung function.

RESULTS

All mice in LPS_1.0 group died before the third instillation. No death after instillation was observed in Control and LPS_0.5 group. Histological analysis revealed that in LPS_0.5 group, 7 days after the third instillation, most bronchus and parabronchial vessels were wrapped by infiltrating monocytes and lymphocyte and alveolar cavities were compressed, which were not observed in control and normal group. Also, ratio of forced expiratory volume in 0.1 second (FEV_0.1) and forced vital capacity (FVC) in LPS_0.5 group was significantly lower (P<0.0001) than both control group and normal group, suggesting ventilatory dysfunction developed after repeatedly intratracheal instillation once a week for 4 weeks.

CONCLUSIONS

Intratracheal instillation of 0.5 mg/kg LPS once a week for 4 weeks can cause chronic lung inflammation in young mice.

Bronchopulmonary dysplasia frequency and risk factors in very low birth weight infants: A 3-year retrospective study

OBJECTIVE:

In this study, the relationship between the frequency of bronchopulmonary dysplasia, perinatal risk factors and other prematurity comorbidities were evaluated in very low birth weight infants.

METHODS:

A total of 872 very low birth weight infants’ files were retrospectively reviewed. The effects of the clinical parameters, such as type of birth, small for gestational age, gender, antenatal steroids, early membrane rupture, chorioamnionitis, surfactant administration, respiratory distress syndrome, patent ductus arteriosus, apnea, early and late sepsis on the frequency of bronchopulmonary dysplasia, were evaluated by binary logistic regression analysis.

RESULTS:

The overall mortality rate was 20.9%. After the first 28-day mortality reduction, the total bronchopulmonary dysplasia frequency was found to be 20.1%. The odds ratio and 95% confidence intervals of the factors affecting the development of bronchopulmonary dysplasia were found to be as follows respectively: respiratory distress syndrome (OR 6.2, 95% CI 3.6–10.6, p<0.01), patent ductus arteriosus (OR 4.9, 95% Cl 2.4–9.9, p<0.01), apnea (OR 4.1, 95% CI 2.5–6.9, p<0.01), late sepsis (OR 2.7, 95% CI 1.6–4.5, p<0.01), early membrane rupture (OR 2.6, 95% Cl 1.2–5.5, p=0.01), and male gender (OR 1.6, 95% CI 1.0-2.7, p=0.04) was found. However, there was no effect of chorioamnionitis, antenatal steroids, small for gestational age, early sepsis and type of birth on bronchopulmonary dysplasia.

CONCLUSION:

Differently from the usual factors which are low birth weight and a gestational week, there was a significant but non-linear risk relationship between respiratory distress syndrome, patent ductus arteriosus, late sepsis, apnea, early membrane rupture, male gender and bronchopulmonary dysplasia.

Indoor/outdoor not-voluptuary-habit pollution and sleep-disordered breathing in children: a systematic review

BACKGROUND

Exposure to environmental pollutants is advocated to be a major risk factor, with increased morbidity and mortality in humans due to acute and chronic airway inflammation. The aim of the present review is to show the literature research regarding the link between the sleep-disordered breathing and exposure to indoor/outdoor pollution in children. We hypothesized that environmental air pollution can play a role in childhood sleep-disordered breathing.

METHODS

We conducted an electronic search in Medline (with PubMed interface), Scopus and the ISI Web of Science using the keywords "sleep" or "sleep apnea" or "sleep disordered breathing" and "pollution" and "children" in "Title/Abstract/Keywords", with language restriction (non-English paper) and no date limitation to present. The tobacco smoke pollution is well established linking and is not considered for the present subject. We examined the strength of the evidence according to the Oxford Centre for Evidence-Based Medicine [2011] and the Centre for Evidence-Based Medicine [2009].

RESULTS

A total of 105 articles were identified, but 97 of these had to be excluded after an accurate reading of the title, abstract or full text. In the end, eight studies were selected for our analysis for a total of a total of 5,826 children. The results suggest an involvement (grade C) of environmental (not from voluptuary habits) pollution in the worsening of sleep-disordered breathing in children.

CONCLUSIONS

To date, some studies reported significant differences between areas with higher and lower pollutants and the interventions on indoor pollution reduced sleep-disordered breathing in children. Therefore, although the relevance of the argument is high, the number of studies and the interest in the subject seems at this time quite limited.

Standardisation of oxygen exposure in the development of mouse models for bronchopulmonary dysplasia

Progress in developing new therapies for bronchopulmonary dysplasia (BPD) is sometimes complicated by the lack of a standardised animal model. Our objective was to develop a robust hyperoxia-based mouse model of BPD that recapitulated the pathological perturbations to lung structure noted in infants with BPD. Newborn mouse pups were exposed to a varying fraction of oxygen in the inspired air (FiO₂) and a varying window of hyperoxia exposure, after which lung structure was assessed by design-based stereology with systemic uniform random sampling. The efficacy of a candidate therapeutic intervention using parenteral nutrition was evaluated to demonstrate the utility of the standardised BPD model for drug discovery. An FiO₂ of 0.85 for the first 14 days of life decreased total alveoli number and concomitantly increased alveolar septal wall thickness, which are two key histopathological characteristics of BPD. A reduction in FiO₂ to 0.60 or 0.40 also caused a decrease in the total alveoli number, but the septal wall thickness was not impacted. Neither a decreasing oxygen gradient (from FiO₂ 0.85 to 0.21 over the first 14 days of life) nor an oscillation in FiO₂ (between 0.85 and 0.40 on a 24 h:24 h cycle) had an appreciable impact on lung development. The risk of missing beneficial effects of therapeutic interventions at FiO₂ 0.85, using parenteral nutrition as an intervention in the model, was also noted, highlighting the utility of lower FiO₂ in selected studies, and underscoring the need to tailor the model employed to the experimental intervention. Thus, a state-of-the-art BPD animal model that recapitulates the two histopathological hallmark perturbations to lung architecture associated with BPD is described. The model presented here, where injurious stimuli have been systematically evaluated, provides a most promising approach for the development of new strategies to drive postnatal lung maturation in affected infants.

Non-invasive positive pressure ventilation for acute asthma in children

BACKGROUND

Asthma is one of the most common reasons for hospital admission among children and constitutes a significant economic burden. Use of non-invasive positive pressure ventilation (NPPV) in the care of children with acute asthma has increased even though evidence supporting the intervention has been considered weak and clinical guidelines do not recommend the intervention. NPPV might be an effective intervention for acute asthma, but no systematic review has been conducted to assess the effects of NPPV as an add-on therapy to usual care in children with acute asthma.

OBJECTIVES

To assess the benefits and harms of NPPV as an add-on therapy to usual care (e.g. bronchodilators and corticosteroids) in children with acute asthma.

SEARCH METHODS

We identified trials from the Cochrane Airways Group Specialised Register (CAGR). The Register contains trial reports identified through systematic searches of bibliographic databases, including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, AMED and PsycINFO, and by handsearching of respiratory journals and meeting abstracts. We also conducted a search of ClinicalTrials.gov (www.ClinicalTrials.gov) and the WHO trials portal (www.who.int/ictrp/en/). We searched all databases from their inception to February 2016, with no restriction on language of publication.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) assessing NPPV as add-on therapy to usual care versus usual care for children (age < 18 years) hospitalised for an acute asthma attack.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts. We retrieved all relevant full-text study reports, independently screened the full text, identified trials for inclusion and identified and recorded reasons for exclusion of ineligible trials. We resolved disagreements through discussion or, if required, consulted a third review author. We recorded the selection process in sufficient detail to complete a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) flow diagram and 'Characteristics of excluded studies' table. We identified the risk of bias of included studies to reduce the risk of systematic error. We contacted relevant study authors when data were missing.

MAIN RESULTS

We included two RCTs that randomised 20 participants to NPPV and 20 participants to control. We assessed both studies as having high risk of bias; both trials assessed effects of bilateral positive airway pressure (BiPAP). Neither trial used continuous positive airway pressure (CPAP). Controls received standard care. Investigators reported no deaths and no serious adverse events (Grades of Recommendation, Assessment, Development and Evaluation (GRADE): very low quality of evidence due to serious risk of bias and serious imprecision of results). Both trials showed a statistically significant reduction in symptom score. One trial did not report a standard deviation (SD), but by using an estimated SD, we found a statistically significantly reduced asthma symptom score (mean difference (MD) -2.50, 95% confidence interval (CI) -4.70 to -0.30, P = 0.03, 19 participants, GRADE: very low quality of evidence). In the other trial, NPPV was associated with a lower total symptom score (5.6 vs 1.9, 16 participants, very low quality of evidence) before cross-over, but investigators did not report an SD, nor could it be estimated from the first phase of the trial, before the cross-over. These gains could be clinically relevant, as a reduction of three or more points in symptom score is considered a clinically meaningful change. Researchers documented five dropouts (12.5%), four of which were due to intolerance to NPPV, and one to respiratory failure requiring intubation. Owing to insufficient reporting in the latter trial and use of different scoring systems, it was not possible to conduct a meta-analysis nor a Trial Sequential Analysis.

AUTHORS' CONCLUSIONS

Current evidence does not permit confirmation or rejection of the effects of NPPV for acute asthma in children. Large RCTs with low risk of bias are warranted.

[Chronic interstitial lung disease in children: Diagnostic approach and management]

Chronic interstitial lung disease (ILD) in children is a heterogeneous group of rare lung disorders characterized by an inflammatory process of the alveolar wall and the pulmonary interstitium that induces gas exchange disorders. The diagnostic approach to an ILD involves three essential steps: recognizing the ILD, appreciating the impact, and identifying the cause. The spectrum of clinical findings depends to a large extent on age. In the newborn, the beginning is often abrupt (neonatal respiratory distress), whereas there is a more gradual onset in infants (failure to thrive, tachypnea, indrawing of the respiratory muscles). In older children, the onset is insidious and the diagnosis can only be made at an advanced stage of the disease. The diagnosis is based on noninvasive methods (clinical history, respiratory function tests, chest X-ray, and high-resolution CT scan) and invasive techniques (bronchoalveolar lavage, transbronchial biopsy, video-assisted thoracoscopic biopsy, and open lung biopsy). The treatment of interstitial lung disease in children depends on the nature of the underlying pathology. The most common therapeutic approach involves the use of corticosteroids and immunosuppressive agents for their anti-inflammatory and antifibrotic effects. Children with ILD also need support therapy (oxygen therapy, nutritional support, treatment of pulmonary arterial hypertension, vaccination). Lung transplantation is discussed in patients with severe respiratory failure.