Exhaled breath condensate pH does not discriminate asymptomatic gastroesophageal reflux or the response to lansoprazole treatment in children with poorly controlled asthma

The Role of Exhaled Breath Condensate in Chronic Inflammatory and Neoplastic Diseases of the Respiratory Tract

Asthma and chronic obstructive pulmonary disease (COPD) are among the most common chronic respiratory diseases. Chronic inflammation of the airways leads to an increased production of inflammatory markers by the effector cells of the respiratory tract and lung tissue. These biomarkers allow the assessment of physiological and pathological processes and responses to therapeutic interventions. Lung cancer, which is characterized by high mortality, is one of the most frequently diagnosed cancers worldwide. Current screening methods and tissue biopsies have limitations that highlight the need for rapid diagnosis, patient differentiation, and effective management and monitoring. One promising non-invasive diagnostic method for respiratory diseases is the assessment of exhaled breath condensate (EBC). EBC contains a mixture of volatile and non-volatile biomarkers such as cytokines, leukotrienes, oxidative stress markers, and molecular biomarkers, providing significant information about inflammatory and neoplastic states in the lungs. This article summarizes the research on the application and development of EBC assessment in diagnosing and monitoring respiratory diseases, focusing on asthma, COPD, and lung cancer. The process of collecting condensate, potential issues, and selected groups of markers for detailed disease assessment in the future are discussed. Further research may contribute to the development of more precise and personalized diagnostic and treatment methods.

Exhaled breath condensate pH determinants in school-aged children: A population-based study

BACKGROUND

Exhaled breath condensate (EBC) pH is a promising biomarker of airway inflammation. Lack of method standardization and interstudy variability precludes its use in clinical practice. While endogenous determinants have been described, underlying mechanisms for variability are mostly unknown. Thus, we aimed to assess the association between asthma and EBC pH in children, while studying potential environmental factors for interstudy variability.

METHODS

A cross-sectional analysis of exhaled breath condensates from 613 children, aged 7-12 years, was conducted. Assessments included lung function and airway reversibility, exhaled nitric oxide, allergic sensitization, and body mass index (BMI). Indoor air quality (IAQ) was assessed in children's classrooms during 5 school days. Post-deaeration EBC pH showed a bimodal distribution, and the sample was split into acidic and alkaline groups. Regression models were constructed to assess the effects of asthma and asthma adjusted to IAQ parameters on EBC pH.

RESULTS

Following adjustment to gender and BMI, asthma was significantly associated with a lower EBC pH in the acidic group. The effect of asthma on EBC pH was independent of IAQ, in both groups. In the acidic group, EBC pH was significantly affected by temperature [β = -0.09 (-0.15, -0.02)] and PM 2.5 concentration [β = -0.16 (-0.32, -0.01)], and in the alkaline group by relative humidity [β = 0.07 (0.02, 0.13)] and concentration of endotoxins [β = -0.06 (-0.1, -0.01)].

CONCLUSION

Our study shows that in addition to individual determinants such as asthma, environmental factors may influence and should be taken into consideration when interpreting EBC pH level in children.

Exhaled Breath Condensate-A Non-Invasive Approach for Diagnostic Methods in Asthma

The pathophysiology of asthma has been intensively studied, but its underlying mechanisms such as airway inflammation, control of airway tone, and bronchial reactivity are still not completely explained. There is an urgent need to implement novel, non-invasive diagnostic tools that can help to investigate local airway inflammation and connect the molecular pathways with the broad spectrum of clinical manifestations of asthma. The new biomarkers of different asthma endotypes could be used to confirm diagnosis, predict asthma exacerbations, or evaluate treatment response. In this paper, we briefly describe the characteristics of exhaled breath condensate (EBC) that is considered to be an interesting source of biomarkers of lung disorders. We look at the composition of EBC, some aspects of the collection procedure, the proposed biomarkers for asthma, and its clinical implications. We also indicate the limitations of the method and potential strategies to standardize the procedure of EBC collection and analytical methods.

Pharmacological and surgical interventions for the treatment of gastro-oesophageal reflux in adults and children with asthma

BACKGROUND

Asthma and gastro-oesophageal reflux disease (GORD) are common medical conditions that frequently co-exist. GORD has been postulated as a trigger for asthma; however, evidence remains conflicting. Proposed mechanisms by which GORD causes asthma include direct airway irritation from micro-aspiration and vagally mediated oesophagobronchial reflux. Furthermore, asthma might precipitate GORD. Thus a temporal association between the two does not establish that GORD triggers asthma.

OBJECTIVES

To evaluate the effectiveness of GORD treatment in adults and children with asthma, in terms of its benefits for asthma.

SEARCH METHODS

The Cochrane Airways Group Specialised Register, CENTRAL, MEDLINE, Embase, reference lists of articles, and online clinical trial databases were searched. The most recent search was conducted on 23 June 2020.

SELECTION CRITERIA

We included randomised controlled trials comparing treatment of GORD in adults and children with a diagnosis of both asthma and GORD versus no treatment or placebo.

DATA COLLECTION AND ANALYSIS

A combination of two independent review authors extracted study data and assessed trial quality. The primary outcome of interest for this review was acute asthma exacerbation as reported by trialists.

MAIN RESULTS

The systematic search yielded a total of 3354 citations; 23 studies (n = 2872 participants) were suitable for inclusion. Included studies reported data from participants in 25 different countries across Europe, North and South America, Asia, Australia, and the Middle East. Participants included in this review had moderate to severe asthma and a diagnosis of GORD and were predominantly adults presenting to a clinic for treatment. Only two studies assessed effects of intervention on children, and two assessed the impact of surgical intervention. The remainder were concerned with medical intervention using a variety of dosing protocols. There was an uncertain reduction in the number of participants experiencing one or more moderate/severe asthma exacerbations with medical treatment for GORD (odds ratio 0.53, 95% confidence interval (CI) 0.17 to 1.63; 1168 participants, 2 studies; low-certainty evidence). None of the included studies reported data related to the other primary outcomes for this review: hospital admissions, emergency department visits, and unscheduled doctor visits. Medical treatment for GORD probably improved forced expiratory volume in one second (FEV₁) by a small amount (mean difference (MD) 0.10 L, 95% CI 0.05 to 0.15; 1333 participants, 7 studies; moderate-certainty evidence) as well as use of rescue medications (MD -0.71 puffs per day, 95% CI -1.20 to -0.22; 239 participants, 2 studies; moderate-certainty evidence). However, the benefit of GORD treatment for morning peak expiratory flow rate was uncertain (MD 6.02 L/min, 95% CI 0.56 to 11.47; 1262 participants, 5 studies). It is important to note that these mean improvements did not reach clinical importance. The benefit of GORD treatment for outcomes synthesised narratively including benefits of treatment for asthma symptoms, quality of life, and treatment preference was likewise uncertain. Data related to adverse events with intervention were generally underreported by the included studies, and those that were available indicated similar rates regardless of allocation to treatment or placebo.

AUTHORS' CONCLUSIONS

Effects of GORD treatment on the primary outcomes of number of people experiencing one or more exacerbations and hospital utilisation remain uncertain. Medical treatment for GORD in people with asthma may provide small benefit for a number of secondary outcomes related to asthma management. This review determined with moderate certainty that with treatment, lung function measures improved slightly, and use of rescue medications for asthma control was reduced. Further, evidence is insufficient to assess results in children, or to compare surgery versus medical therapy.

Respiratory manifestations of gastro-oesophageal reflux in children

Gastro-oesophageal reflux disease (GORD) is a complex problem in children. Suspected respiratory manifestations of GORD, such as asthma, chronic cough and laryngitis, are commonly encountered in the paediatric practice, but continue to be entities with more questions than answers. The accuracy of diagnostic tests (ie, pH or pH-impedance monitoring, laryngoscopy, endoscopy) for patients with suspected extraoesophageal manifestations of GORD is suboptimal and therefore whether there is a causal relationship between these conditions remains largely undetermined. An empiric trial of proton pump inhibitors can help individual children with undiagnosed respiratory symptoms and suspicion of GORD, but the response to therapy is unpredictable, and in any case what may be being observed is spontaneous improvement. Furthermore, the safety of these agents has been called into question. Poor response to antireflux therapy is an important trigger to search for non-gastro-oesophageal reflux causes for patients' symptoms. Evidence for the assessment of children with suspected extraoesophageal manifestations of GORD is scanty and longitudinal studies with long-term follow-up are urgently required.

Pediatric Gastroesophageal Reflux Clinical Practice Guidelines: Joint Recommendations of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition

This document serves as an update of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) 2009 clinical guidelines for the diagnosis and management of gastroesophageal reflux disease (GERD) in infants and children and is intended to be applied in daily practice and as a basis for clinical trials. Eight clinical questions addressing diagnostic, therapeutic and prognostic topics were formulated. A systematic literature search was performed from October 1, 2008 (if the question was addressed by 2009 guidelines) or from inception to June 1, 2015 using Embase, MEDLINE, the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Clinical Trials. The approach of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) was applied to define and prioritize outcomes. For therapeutic questions, the quality of evidence was also assessed using GRADE. Grading the quality of evidence for other questions was performed according to the Quality Assessment of Studies of Diagnostic Accuracy (QUADAS) and Quality in Prognostic Studies (QUIPS) tools. During a 3-day consensus meeting, all recommendations were discussed and finalized. In cases where no randomized controlled trials (RCT; therapeutic questions) or diagnostic accuracy studies were available to support the recommendations, expert opinion was used. The group members voted on each recommendation, using the nominal voting technique. With this approach, recommendations regarding evaluation and management of infants and children with GERD to standardize and improve quality of care were formulated. Additionally, 2 algorithms were developed, 1 for infants <12 months of age and the other for older infants and children.

Aspiration Risk and Respiratory Complications in Patients with Esophageal Atresia

Chronic, long-term respiratory morbidity (CRM) is common in patients with a history of repaired congenital esophageal atresia, typically associated with tracheoesophageal fistula (EA/TEF). EA/TEF patients are at high risk of having aspiration, and retrospective studies have associated CRM with both recurrent aspiration and atopy. However, studies evaluating the association between CRM in this population and either aspiration or atopy have reported conflicting results. Furthermore, CRM in this population may be due to other related conditions as well, such as tracheomalacia and/or recurrent infections. Aspiration is difficult to confirm, short of lung biopsy. Moreover, even within the largest evidence base assessing the association between CRM and aspiration, which has evaluated the potential relationship between gastroesophageal reflux and asthma, findings are contradictory. Studies attempting to relate CRM to prior aspiration events may inadequately estimate the frequency and severity of previous aspiration episodes. There is convincing evidence documenting that chronic, massive aspiration in patients with repaired EA/TEF is associated with the development of bronchiectasis. While chronic aspiration is likely associated with other CRM in patients with repaired EA/TEF, this does not appear to have been confirmed by the data currently available. Prospective studies that systematically evaluate aspiration risk and allergic disease in patients with repaired EA/TEF and document subsequent CRM will be needed to clarify the causes of CRM in this population. Given the prevalence of CRM, patients with repaired EA/TEF should ideally receive regular follow-up by multidisciplinary teams with expertise in this condition, throughout both childhood and adulthood.

Exhaled Breath Condensate: Technical and Diagnostic Aspects

Purpose. The aim of this study was to evaluate the 30-year progress of research on exhaled breath condensate in a disease-based approach. Methods. We searched PubMed/Medline, ScienceDirect, and Google Scholar using the following keywords: exhaled breath condensate (EBC), biomarkers, pH, asthma, gastroesophageal reflux (GERD), smoking, COPD, lung cancer, NSCLC, mechanical ventilation, cystic fibrosis, pulmonary arterial hypertension (PAH), idiopathic pulmonary fibrosis, interstitial lung diseases, obstructive sleep apnea (OSA), and drugs. Results. We found 12600 related articles in total in Google Scholar, 1807 in ScienceDirect, and 1081 in PubMed/Medline, published from 1980 to October 2014. 228 original investigation and review articles were eligible. Conclusions. There is rapidly increasing number of innovative articles, covering all the areas of modern respiratory medicine and expanding EBC potential clinical applications to other fields of internal medicine. However, the majority of published papers represent the results of small-scale studies and thus current knowledge must be further evaluated in large cohorts. In regard to the potential clinical use of EBC-analysis, several limitations must be pointed out, including poor reproducibility of biomarkers and absence of large surveys towards determination of reference-normal values. In conclusion, contemporary EBC-analysis is an intriguing achievement, but still in early stage when it comes to its application in clinical practice.

The metabolomics of asthma control: a promising link between genetics and disease

Short-acting β agonists (e.g., albuterol) are the most commonly used medications for asthma, a disease that affects over 300 million people in the world. Metabolomic profiling of asthmatics taking β agonists presents a new and promising resource for identifying the molecular determinants of asthma control. The objective is to identify novel genetic and biochemical predictors of asthma control using an integrative "omics" approach. We generated lipidomic data by liquid chromatography tandem mass spectrometry (LC-MS), - using plasma samples from 20 individuals with asthma. The outcome of interest was a binary indicator of asthma control defined by the use of albuterol inhalers in the preceding week. We integrated metabolomic data with genome-wide genotype, gene expression, and methylation data of this cohort to identify genomic and molecular indicators of asthma control. A Conditional Gaussian Bayesian Network (CGBN) was generated using the strongest predictors from each of these analyses. Integrative and metabolic pathway over-representation analyses (ORA) identified enrichment of known biological pathways within the strongest molecular determinants. Of the 64 metabolites measured, 32 had known identities. The CGBN model based on four SNPs (rs9522789, rs7147228, rs2701423, rs759582) and two metabolites-monoHETE_0863 and sphingosine-1-phosphate (S1P) could predict asthma control with an AUC of 95%. Integrative ORA identified 17 significantly enriched pathways related to cellular immune response, interferon signaling, and cytokine-related signaling, for which arachidonic acid, PGE2 and S1P, in addition to six genes (CHN1, PRKCE, GNA12, OASL, OAS1, and IFIT3) appeared to drive the pathway results. Of these predictors, S1P, GNA12, and PRKCE were enriched in the results from integrative and metabolic ORAs. Through an integrative analysis of metabolomic, genomic, and methylation data from a small cohort of asthmatics, we implicate altered metabolic pathways, related to sphingolipid metabolism, in asthma control. These results provide insight into the pathophysiology of asthma control.

A review on airway biomarkers: exposure, effect and susceptibility

Current research in pulmonology requires the use of biomarkers to investigate airway exposure and diseases, for both diagnostic and prognostic purposes. The traditional approach based on invasive approaches (lung lavages and biopsies) can now be replaced, at least in part, through the use of non invasively collected specimens (sputum and breath), in which biomarkers of exposure, effect and susceptibility can be searched. The discovery of specific lung-related proteins, which can spill over in blood or excreted in urine, further enhanced the spectrum of airway specific biomarkers to be studied. The recent introduction of high-performance 'omic' technologies - genomics, proteomics and metabolomics, and the rate at which biomarker candidates are being discovered, will permit the use of a combination of biomarkers for a more precise selection of patient with different outcomes and responses to therapies. The aim of this review is to critically evaluate the use of airway biomarkers in the context of research and clinical practice.