Volatile organic breath components and exercise induced bronchoconstriction in asthmatic children.

INTRODUCTION: Asthma is one of the most common chronic diseases in childhood and is generally characterized by exercise induced bronchoconstriction (EIB). Assessing EIB is time consuming and expensive as it requires a fully equipped pulmonary function laboratory. Analysis of volatile organic compounds (VOCs) in breath is a novel technique for examining biomarkers which may associate with asthma features. The aim of this pilot study was to identify potential markers in the relationship between EIB and VOCs. METHODS: Children between four and 14 years old were asked to provide a breath sample prior to undergoing an exercise challenge test to assess for EIB. RESULTS: Breath samples were collected and analyzed in 46 asthmatic children, 21 with EIB and 25 without EIB (NO-EIB). Molecular features (MFs) were not significantly different between EIB and NO-EIB controls. 29 of the 46 children were corticosteroid naïve, 10 with EIB and 13 without. In the corticosteroid naïve group EIB was associated with increased MF23 and MF14 in the lower breath sample (p-value < 0.05). CONCLUSION: This pilot study shows that EIB was related to an increased MF14 and MF23 in corticosteroid naïve children. The tentative identities of these compounds are octanal and dodecane/tetradecane respectively. These candidate biomarkers have a potential to enable non-invasive diagnosis of EIB in steroid-naïve children. Trial registration This study is registered in the Netherlands trial register (trial no. NL6087) at 14 February 2017.

The potential of breath analysis to improve outcome for patients with lung cancer.

Lung cancer remains the most common cause of cancer related death in both the UK and USA. Development of diagnostic approaches that have the ability to detect lung cancer early are a research priority with potential to improve survival. Analysis of exhaled breath metabolites, or volatile organic compounds (VOCs) is an area of considerable interest as it could fulfil such requirements. Numerous studies have shown that VOC profiles are different in the breath of patients with lung cancer compared to healthy individuals or those with non-malignant lung diseases. This review provides a scientific and clinical assessment of the potential value of a breath test in lung cancer. It discusses the current understanding of metabolic pathways that contribute to exhaled VOC production in lung cancer and reviews the research conducted to date. Finally, we highlight important areas for future research and discuss how a breath test could be incorporated into various clinical pathways.

Prevalence of rhinoviruses in young children of an unselected birth cohort from the Netherlands.

Rhinovirus (RV) is a frequent pathogen in young children, eliciting symptoms ranging from common colds to wheezing illnesses and lower respiratory tract infections. The recently identified RV-C seems to be associated with asthma exacerbations and more severe disease, but results vary. We studied the prevalence and severity of infection with RV in an unselected birth cohort. Children with respiratory symptoms entered the symptomatic arm of the cohort and were compared with asymptomatic children. Severity of wheezing and other respiratory symptoms was registered. Respiratory viruses were evaluated using throat and nasopharyngeal swabs on first presentation and after recovery (wheezing children). RV genotyping was performed on RV-PCR positive samples. RV was the most prevalent respiratory virus and was found in 58/140 symptomatic children (41%), 24/96 (25%) control children and 19/74 (26%) wheezing symptomatic children after recovery (p <0.05) and did not differ between wheezing and non-wheezing symptomatic children-respectively, 42% (38/90) and 40% (20/50). RV-A was the most commonly detected species (40/68, 59%), followed by RV-C (22/68, 32%) and RV-B (6/68, 9%). RV-B was more frequently detected in asymptomatic children (5/6, p <0.05). There was no significant difference in the frequency of RV species between wheezing and non-wheezing symptomatic children. Children with RV mono-infection had more severe symptoms, but no association between RV species and severity of disease was seen. In an unselected birth cohort from the Netherlands with mild respiratory disease RV was the most prevalent respiratory virus. RV(-C) infection was not associated with more severe disease or wheezing.

Detection of Airway Colonization by Aspergillus fumigatus by Use of Electronic Nose Technology in Patients with Cystic Fibrosis.

Currently, there is no noninvasive test that can reliably diagnose early invasive pulmonary aspergillosis (IA). An electronic nose (eNose) can discriminate various lung diseases through an analysis of exhaled volatile organic compounds. We recently published a proof-of-principle study showing that patients with prolonged chemotherapy-induced neutropenia and IA have a distinct exhaled breath profile (or breathprint) that can be discriminated with an eNose. An eNose is cheap and noninvasive, and it yields results within minutes. We determined whether Aspergillus fumigatus colonization may also be detected with an eNose in cystic fibrosis (CF) patients. Exhaled breath samples of 27 CF patients were analyzed with a Cyranose 320. Culture of sputum samples defined the A. fumigatus colonization status. eNose data were classified using canonical discriminant analysis after principal component reduction. Our primary outcome was cross-validated accuracy, defined as the percentage of correctly classified subjects using the leave-one-out method. The P value was calculated by the generation of 100,000 random alternative classifications. Nine of the 27 subjects were colonized by A. fumigatus. In total, 3 subjects were misclassified, resulting in a cross-validated accuracy of the Cyranose detecting IA of 89% (P = 0.004; sensitivity, 78%; specificity, 94%). Receiver operating characteristic (ROC) curve analysis showed an area under the curve (AUC) of 0.89. The results indicate that A. fumigatus colonization leads to a distinctive breathprint in CF patients. The present proof-of-concept data merit external validation and monitoring studies.

Integration of electronic nose technology with spirometry: validation of a new approach for exhaled breath analysis.

New 'omics'-technologies have the potential to better define airway disease in terms of pathophysiological and clinical phenotyping. The integration of electronic nose (eNose) technology with existing diagnostic tests, such as routine spirometry, can bring this technology to 'point-of-care'. We aimed to determine and optimize the technical performance and diagnostic accuracy of exhaled breath analysis linked to routine spirometry. Exhaled breath was collected in triplicate in healthy subjects by an eNose (SpiroNose) based on five identical metal oxide semiconductor sensor arrays (three arrays monitoring exhaled breath and two reference arrays monitoring ambient air) at the rear end of a pneumotachograph. First, the influence of flow, volume, humidity, temperature, environment, etc, was assessed. Secondly, a two-centre case-control study was performed using diagnostic and monitoring visits in day-to-day clinical care in patients with a (differential) diagnosis of asthma, chronic obstructive pulmonary disease (COPD) or lung cancer. Breathprint analysis involved signal processing, environment correction based on alveolar gradients and statistics based on principal component (PC) analysis, followed by discriminant analysis (Matlab2014/SPSS20). Expiratory flow showed a significant linear correlation with raw sensor deflections (R(2) = 0.84) in 60 healthy subjects (age 43 ± 11 years). No correlation was found between sensor readings and exhaled volume, humidity and temperature. Exhaled data after environment correction were highly reproducible for each sensor array (Cohen's Kappa 0.81-0.94). Thirty-seven asthmatics (41 ± 14.2 years), 31 COPD patients (66 ± 8.4 years), 31 lung cancer patients (63 ± 10.8 years) and 45 healthy controls (41 ± 12.5 years) entered the cross-sectional study. SpiroNose could adequately distinguish between controls, asthma, COPD and lung cancer patients with cross-validation values ranging between 78-88%. We have developed a standardized way to integrate eNose technology with spirometry. Signal processing techniques and environmental background correction ensured that the multiple sensor arrays within the SpiroNose provided repeatable and interchangeable results. SpiroNose discriminated controls and patients with asthma, COPD and lung cancer with promising accuracy, paving the route towards point-of-care exhaled breath diagnostics.

The application of FAIMS gas analysis in medical diagnostics.

There is an ever increasing need to develop new tools to aid in the diagnosis and monitoring of human diseases. Such tools will ultimately reduce the cost of healthcare by identifying disease states more quickly and cheaply than current practices. One method showing promise is the analysis of gas-phase biomarkers from human breath, urine, sweat and stool that reflect bodily metabolism. Analysis of these volatiles by GC MS requires specialised infra-structure and staff, making it unsuitable for a clinical setting. Point of care sensor based technologies such as eNoses often suffer from stability and sensitivity issues. Field-Asymmetric Ion Mobility Spectrometry (FAIMS) has potential to fulfil this clinical need. In this paper we review the medical need, the technology, sampling methods and medical evidence thus far. We conclude with reflecting on future developmental steps necessary to bring the device into medical practice.

Predicting steroid responsiveness in patients with asthma using exhaled breath profiling.

BACKGROUND: Exhaled breath contains disease-dependent volatile organic compounds (VOCs), which may serve as biomarkers distinguishing clinical phenotypes in asthma. Their measurement may be particularly beneficial in relation to treatment response. OBJECTIVE: Our aim was to compare the performance of electronic nose (eNose) breath analysis with previously investigated techniques (sputum eosinophils, exhaled nitric oxide (FeNO) and airway hyperresponsiveness) to discriminate asthma from controls and identify steroid responsiveness in steroid-free patients. Trial registration ACTRN12613000038796. METHODS: Twenty-five patients with mild/moderate asthma had their inhaled steroid treatment discontinued until loss of control or 28 days. They were subsequently treated with oral prednisone 30 mg/day for 14 days. Steroid responsiveness was defined as an increase of either > 12% FEV1 or > 2 doubling doses PC20 AMP. Steroid-free assessment of sputum eosinophils, FeNO and exhaled breath VOCs were used to construct algorithms predicting steroid responsiveness. Performance characteristics were compared by ROC analysis. RESULTS: The eNose discriminated between asthma and controls (area under the curve = 0.766 ± 0.14; P = 0.002) with similar accuracy to FeNO (0.862 ± 0.12; P < 0.001) and sputum eosinophils (0.814 ± 0.15; P < 0.001). Steroid responsiveness was predicted with greater accuracy by VOC-analysis (AUC = 0.883 ± 0.16; P = 0.008) than FeNO (0.545 ± 0.28; P = 0.751) or sputum eosinophils (0.610 ± 0.29; P = 0.441). CONCLUSIONS AND CLINICAL RELEVANCE: Breath analysis by eNose can identify asthmatic patients and may be used to predict their response to steroids with greater accuracy than sputum eosinophils or FeNO. This implies a potential role for breath analysis in the tailoring of treatment for asthma patients.

Exhaled breath analysis by electronic nose in airways disease. Established issues and key questions.

Exhaled air contains many volatile organic compounds (VOCs) that are the result of normal and disease-associated metabolic processes anywhere in the body. Different omics techniques can assess the pattern of these VOCs. One such omics technique suitable for breath analysis is represented by electronic noses (eNoses), providing fingerprints of the exhaled VOCs, called breathprints. Breathprints have been shown to be altered in different disease states, including in asthma and COPD. This review describes the current status on clinical validation and application of breath analysis by electronic noses in the diagnosis and monitoring of chronic airways diseases. Furthermore, important methodological issues including breath sampling, modulating factors and incompatibility between eNoses are raised and discussed. Next steps towards clinical application of electronic noses are provided, including further validation in suspected disease, assessment of the influence of different comorbidities, the value in longitudinal monitoring of patients with asthma and COPD and the possibility to predict treatment responses. Eventually, a Breath Cloud may be constructed, a large database containing disease-specific breathprints. When collaborative efforts are put into optimization of this technique, it can provide a rapid and non-invasive first line diagnostic test.

Exhaled molecular profiles in the assessment of cystic fibrosis and primary ciliary dyskinesia.

BACKGROUND: Early diagnosis and monitoring of disease activity are essential in cystic fibrosis (CF) and primary ciliary dyskinesia (PCD). We aimed to establish exhaled molecular profiles as the first step in assessing the potential of breath analysis. METHODS: Exhaled breath was analyzed by electronic nose in 25 children with CF, 25 with PCD and 23 controls. Principle component reduction and canonical discriminant analysis were used to construct internally cross-validated ROC curves. RESULTS: CF and PCD patients had significantly different breath profiles when compared to healthy controls (CF: sensitivity 84%, specificity 65%; PCD: sensitivity 88%, specificity 52%) and from each other (sensitivity 84%, specificity 60%). Patients with and without exacerbations had significantly different breath profiles (CF: sensitivity 89%, specificity 56%; PCD: sensitivity 100%, specificity 90%). CONCLUSION: Exhaled molecular profiles significantly differ between patients with CF, PCD and controls. The eNose may have potential in disease monitoring based on the influence of exacerbations on the VOC-profile.

Effect of transportation and storage using sorbent tubes of exhaled breath samples on diagnostic accuracy of electronic nose analysis.

Many (multi-centre) breath-analysis studies require transport and storage of samples. We aimed to test the effect of transportation and storage using sorbent tubes of exhaled breath samples for diagnostic accuracy of eNose and GC-MS analysis. As a reference standard for diagnostic accuracy, breath samples of asthmatic patients and healthy controls were analysed by three eNose devices. Samples were analysed by GC-MS and eNose after 1, 7 and 14 days of transportation and storage using sorbent tubes. The diagnostic accuracy for eNose and GC-MS after storage was compared to the reference standard. As a validation, the stability was assessed of 15 compounds known to be related to asthma, abundant in breath or related to sampling and analysis. The reference test discriminated asthma and healthy controls with a median AUC (range) of 0.77 (0.72-0.76). Similar accuracies were achieved at t1 (AUC eNose 0.78; GC-MS 0.84), t7 (AUC eNose 0.76; GC-MS 0.79) and t14 (AUC eNose 0.83; GC-MS 0.84). The GC-MS analysis of compounds showed an adequate stability for all 15 compounds during the 14 day period. Short-term transportation and storage using sorbent tubes of breath samples does not influence the diagnostic accuracy for discrimination between asthma and health by eNose and GC-MS.

External validation of exhaled breath profiling using an electronic nose in the discrimination of asthma with fixed airways obstruction and chronic obstructive pulmonary disease.

BACKGROUND: Fixed airflow limitation can be found both in asthma and chronic obstructive pulmonary disease (COPD), posing a day-to-day diagnostic challenge. OBJECTIVE: We aimed to determine the external validity of metabolomic analysis of exhaled air by electronic nose for distinguishing asthma and COPD in patients with fixed airways obstruction. METHODS: One hundred patients were included in a cross-sectional design: 60 asthma patients: 21 with fixed airways obstruction (fixed asthma), 39 with reversible airways obstruction (classic asthma) and 40 COPD patients (GOLD stages II-III). Standardized sampling of exhaled breath was performed and volatile organic compounds were captured using an electronic nose resulting in breathprints. External validity in newly recruited patients (validation sets) was tested using a previous and independent training set. Breathprints were analysed by principal component and canonical discriminant analysis and area under the curve (AUC) of receiver operating characteristic curves. RESULTS: External validity of breathprints showed 88% accuracy for distinguishing fixed asthma from COPD (AUC 0.95, 95% CI 0.84-1.00, sensitivity 85%, specificity 90%) and 83% for classic asthma (AUC 0.93, 95% CI 0.87-1.00, sensitivity 91%, specificity 90%) (both P<0.001). Discriminative accuracy was not confounded by current smoking. CONCLUSIONS AND CLINICAL RELEVANCE: External validation of exhaled breath molecular profiling shows high accuracy in distinguishing asthma and COPD in newly recruited patients with fixed airways obstruction. Exhaled air analysis may therefore reduce misdiagnosis in obstructive airways diseases, potentially leading to more appropriate management.