Collecting Exhaled Breath Condensate (EBC) with Two Condensers in Series: A Promising Technique for Studying the Mechanisms of EBC Formation, and the Volatility of Selected Biomarkers

A European Respiratory Society technical standard: exhaled biomarkers in lung disease

Breath tests cover the fraction of nitric oxide in expired gas (F_eNO), volatile organic compounds (VOCs), variables in exhaled breath condensate (EBC) and other measurements. For EBC and for F_eNO, official recommendations for standardised procedures are more than 10 years old and there is none for exhaled VOCs and particles. The aim of this document is to provide technical standards and recommendations for sample collection and analytic approaches and to highlight future research priorities in the field. For EBC and F_eNO, new developments and advances in technology have been evaluated in the current document. This report is not intended to provide clinical guidance on disease diagnosis and management.Clinicians and researchers with expertise in exhaled biomarkers were invited to participate. Published studies regarding methodology of breath tests were selected, discussed and evaluated in a consensus-based manner by the Task Force members.Recommendations for standardisation of sampling, analysing and reporting of data and suggestions for research to cover gaps in the evidence have been created and summarised.Application of breath biomarker measurement in a standardised manner will provide comparable results, thereby facilitating the potential use of these biomarkers in clinical practice.

Exhaled breath analysis in suspected cases of non-small-cell lung cancer: a cross-sectional study

Lung cancer is one of the most frequently diagnosed cancers worldwide and is still the leading cause of cancer-related deaths. There is a considerable interest in finding diagnostic methods in the disease's earliest stages. A complementary approach to imaging techniques could be provided by exhaled breath gas phase and exhaled breath condensate (EBC) analysis. The aim of this study was to quantify various biomarkers in the exhaled breath gas phase and EBC in suspected cases of non-small-cell lung cancer (NSCLC). The study involved 138 subjects with suspected lung cancer, 71 of whom had a subsequent diagnosis of NSCLC. The diagnostic power of a combination of hydrogen peroxide (H₂O₂)-EBC, and exhaled pentane, 2-methyl pentane, hexane, ethyl benzene, heptanal, trans-2-nonenal in distinguishing NSCLC and non-NSCLC subjects was poor-to-fair (area under the curve (AUC) = 0.68), similar to that of smoking history alone (expressed as pack-years, AUC = 0.70); a further improvement was observed when smoking history was combined with exhaled compounds (AUC = 0.80). The diagnostic power was increased in those patients with little or no past smoke exposure (AUC = 0.92) or where past smoke exposure was up to 30 pack-years (AUC = 0.85). Exhaled substances had a good accuracy in discriminating suspected cancerous cases only in those subjects with a modest smoking history (≤ 30 pack-years), but the inclusion of other exhaled biomarkers may increase the overall accuracy, regardless of tobacco smoke.

Concentration of exhaled breath condensate biomarkers after fractionated collection based on exhaled CO2 signal

A standard procedure for exhaled breath condensate (EBC) collection is still lacking. The aim of this study was to compare the concentration of several biomarkers in whole (W-EBC) and fractionated EBC (A-EBC), the latter collected starting from CO2 ≥ 50% increase during exhalation. Forty-five healthy non-smokers or asymptomatic light smokers were enrolled. Total protein concentrations in W-EBC and A-EBC were overlapping (median: 0.7 mg l(-1) in both cases), whereas mitochondrial DNA was higher in A-EBC (0.021 versus 0.011 ng ml(-1)), indicating a concentration rather than a dilution of lining fluid droplets in the last portion of exhaled air. H2O2 (0.13 versus 0.08 µM), 8-isoprostane (4.9 versus 4.4 pg ml(-1)), malondialdehyde (MDA) (4.2 versus 3.2 nM) and 4-hydroxy-2-nonhenal (HNE) (0.78 versus 0.66 nM) were all higher in W-EBC, suggesting a contribution from the upper airways to oxidative stress biomarkers in apparently healthy subjects. NH4(+) was also higher in W-EBC (median: 590 versus 370 µM), with an estimated increase over alveolar and bronchial air by a factor 1.5. pH was marginally, but significantly higher in W-EBC (8.05 versus 8.01). In conclusion, the fractionation of exhaled air may be promising in clinical and occupational medicine.

Hydrogen peroxide in exhaled breath condensate in asthmatic children during acute exacerbation and after treatment

BACKGROUND

In asthmatics, the concentration of hydrogen peroxide (H(2)O(2)) in exhaled breath condensate (EBC) has been found to be increased and to be related to airway inflammation.

OBJECTIVE

The aim of this study was to determine whether in children with acute exacerbation, exhaled H(2)O(2) levels could be influenced by treatment and linked to airway obstruction.

METHODS

Twenty-two asthmatic children (mean age 9.4 years, range 6-14) with asthma exacerbation and 12 healthy children (mean age 11.7 years, range 7-15) were enrolled. Concentrations of exhaled H(2)O(2) before and after standard treatment for asthma attack were compared with those of controls and with clinical observation. Asthmatic children and controls underwent spirometry and skin prick tests to common aeroallergens.

RESULTS

Exhaled H(2)O(2) concentrations were significantly higher in children with asthma both before (median 0.273 µM; p < 0.001) and after pharmacologic treatment (median 0.303 µM; p = 0.001) compared to control values (median 0.045 µM). After treatment, exhaled H(2)O(2) concentrations remained significantly higher in children with and without auscultatory wheezing than in controls (p = 0.034 and p < 0.001, respectively). EBC H(2)O(2) levels in asthmatics before treatment did not differ from those after treatment. No correlation was found between H(2)O(2) and forced expiratory volume in 1 s values. All asthmatics but one were atopics.

CONCLUSIONS

In children with acute asthma exacerbation, exhaled H(2)O(2) concentrations in EBC are significantly elevated. In the short-term follow-up, H(2)O(2) levels remain at high levels and are not correlated with lung function or improvement in symptoms.

Methodological aspects of exhaled breath condensate collection and analysis

The collection and analysis of exhaled breath condensate (EBC) may be useful for the management of patients with chronic respiratory disease at all ages. It is a promising technique due to its apparent simplicity and non-invasiveness. EBC does not disturb an ongoing respiratory inflammation. However, the methodology remains controversial, as it is not yet standardized. The current diversity of the methods used to collect and preserve EBC, the analytical pitfalls and the high degree of within-subject variability are the main issues that hamper further development into a clinical useful technique. In order to facilitate the process of standardization, a simplified schematic approach is proposed. An update of available data identified open issues on EBC methodology. These issues were then classified into three separate conditions related to their influence before, during or after the condensation process: (1) pre-condenser conditions related to subject and/or environment; (2) condenser conditions related to condenser equipment; and (3) post-condenser conditions related to preservation and/or analysis. This simplified methodological approach highlights the potential influence of the many techniques used before, during and after condensation of exhaled breath. It may also serve as a methodological checklist for a more systematical approach of EBC research and development.

Effect of exposure to detergents and other chemicals on biomarkers of pulmonary response in exhaled breath from hospital cleaners: a pilot study

PURPOSE

The main aim of the study was to provide evidence whether professional cleaning was associated with biomarkers of lung damage in non-invasively collected biological fluids (exhaled air and exhaled breath condensate--EBC).

MATERIALS AND METHODS

This cross-sectional study involved 40 cleaners regularly exposed to cleaning detergents and 40 controls. The subjects completed a standard questionnaire from European Community Respiratory Health Survey (ECRHS II) and underwent a spirometry. Fractional exhaled nitric oxide (F(E)NO) was measured online, and pH, ammonium (NH(4) (+)), H(2)O(2) and 4-hydroxynonenal (4-HNE) were assayed in EBC.

RESULTS

Among the cleaners, the frequency of asthma and rhinitis was, respectively, 2.5 and 20%. The most frequently reported symptoms were sneezing (27.5%), nasal and/or pharyngeal pruritus (25%), ocular pruritus (22.5%) and cough (22.5%). There were no significant differences in comparison with the control group. Median F(E)NO levels were higher in African than in Caucasian cleaners (21.5 [16.5-30.0] ppb and 18.0 [13.5-20.5] ppb; p < 0.05). H(2)O(2)-EBC (0.26 [0.09-0.53] μM vs. 0.07 [0.04-0.15] μM; p < 0.01), NH(4) (+)-EBC (857 [493-1,305] μM vs. 541 [306-907] μM; p < 0.01) and pH-EBC (8.17 [8.09-8.24] vs. 8.06 [7.81-8.10]; p < 0.01) were higher in the cleaners than in the controls. Finally, the cleaners showed significant correlations between pH-EBC and NH(4) (+)-EBC (r = 0.33, p < 0.05) and a weak correlation between 4-HNE-EBC and H(2)O(2)-EBC (r = 0.37, p < 0.05).

CONCLUSION

The promising role of EBC analysis in biomonitoring of exposed workers was confirmed. It was also possible to identify the potential biomarkers of exposure to alkaline products (increased ammonium-EBC and pH-EBC levels) and potential biomarkers of oxidative stress (increased H(2)O(2)-EBC levels correlated with 4-HNE-EBC levels) in workers with no signs of airway diseases.

Selected ion flow tube mass spectrometry of exhaled breath condensate headspace

Collection of exhaled breath condensate (EBC) is a relatively simple noninvasive method of breath analysis; however, no data have been reported that would relate concentration of volatile compounds in EBC to their gaseous concentrations in exhaled air. The aim of the study was to investigate which volatile compounds are present in EBC and how their concentrations relate to results of direct breath analysis. Thus, samples of EBC were collected in a standard way from several subjects and absolute levels of several common volatile breath metabolites (ammonia, acetone, ethanol, methanol, propanol, isoprene, hydrogen cyanide, formaldehyde and acetaldehyde) were then determined in their headspace using selected ion flow tube mass spectrometry (SIFT-MS). Results are compared with those from on-line breath analyses carried out immediately before collecting the EBC samples. It has been demonstrated that SIFT-MS can be used to quantify the concentrations of volatiles in EBC samples and that, for methanol, ammonia, ethanol and acetone, the EBC concentrations correlate with the direct breath levels. However, the EBC concentrations of isoprene, formaldehyde, acetaldehyde, hydrogen cyanide and propanol do not correlate with direct breath measurements.