Breath tests cover the fraction of nitric oxide in expired gas (), volatile organic compounds (VOCs), variables in exhaled breath condensate (EBC) and other measurements. For EBC and for , 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, 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.

Endogenous airway acidification, as assessed by pH in expired breath condensate, has been implicated in asthma pathophysiology. We measured pH in breath condensate of patients with inflammatory airway diseases in stable condition and examined its relationship with the inflammatory process (as assessed by differential cell counts in induced sputum), oxidative stress (as assessed by H(2)O(2) and 8-isoprostane), and nitric oxide metabolism (as assessed by total nitrate/nitrite). We studied 40 patients with bronchial asthma (20 with moderate disease, forced expiratory volume in 1 second 60 [10]% SD predicted), 20 patients with bronchiectasis, 20 patients with chronic obstructive pulmonary disease (COPD), and 10 normal subjects. Mean (95% confidence intervals) pH values were significantly lower in patients with COPD and bronchiectasis compared with patients with asthma and control subjects (7.16, 7.09-7.23 and 7.11, 7.04-7.19 versus 7.43, 7.35-7.52 and 7.57, 7.51-7.64, respectively, p < 0.0001). Patients with moderate asthma had significantly lower values compared with mild and control subjects. In patients with COPD and bronchiectasis, the values of pH were significantly correlated with both sputum neutrophilia and oxidative stress. Respectively, in patients with moderate asthma, a significant correlation was observed between pH and sputum eosinophilia, total nitrate/nitrite, and oxidative stress. The pH of the expired breath condensate might be a simple, noninvasive, inexpensive, and easily repeatable procedure for the evaluation of the inflammatory process in airway diseases.

Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow obstruction and a neutrophilic inflammation. Exhaled nitric oxide (NO) may be a marker of disease activity in a variety of lung diseases. We measured exhaled NO in patients with documented COPD and investigated whether the concentration of exhaled NO is related to the severity of disease as defined by lung function. We also investigated whether concentration of exhaled NO was different in COPD patients who received inhaled steroids compared with steroid-naive patients. We studied 13 current smokers with COPD, eight exsmokers with COPD, 12 patients with unstable COPD (exacerbation or severe disease), and 10 smokers with chronic bronchitis without airflow limitation. Exhaled NO levels were significantly higher in patients with unstable COPD (12.7 +/- 1.5 ppb) than in other groups (p < 0.01). Exhaled NO levels were significantly higher in smokers with COPD than in smokers with chronic bronchitis (4.3 +/- 0.5 versus 2.5 +/- 0.5 ppb, p < 0.05), and were even higher in patients with COPD who had stopped smoking (6.3 +/- 0.6 ppb, p < 0.01). Exhaled NO levels showed a significant negative correlation with their lung function assessed by % predicted FEV1 values (r = -0.6, p < 0.001). Exhaled NO levels in patients treated with inhaled steroids were significantly higher compared with steroid-naive patients (8.2 +/- 1.2 ppb versus 5 +/- 0.4 ppb, p < 0.05), but the first group included more severe patients as assessed by lung function. We conclude that exhaled NO could serve as a useful, practical marker for monitoring disease activity in COPD.

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Background-Bronchiectasis is a chronic inflammatory lung disease associated with increased production of oxidants due mostly to neutrophilic inflammation. Induction of heme oxygenase (HO-1) by reactive oxygen species is a general cytoprotective mechanism against oxidative stress. HO-1 catabolises heme to bilirubin, free iron and carbon monoxide (CO). Exhaled CO measurements may therefore reflect an oxidative stress and be clinically useful in the detection and management of inflammatory lung disorders. Methods-The levels of exhaled CO of 42 non-smoking patients with bronchiectasis treated or not treated with inhaled corticosteroids were compared with CO levels in 37 normal non-smoking subjects. Results-Levels of exhaled CO were raised in patients with bronchiectasis, both those treated with inhaled corticosteroids (n = 27, median 5.5 ppm, 95% CI 5.16 to 7.76) and those not treated with inhaled corticosteroids (n = 15, median 6.0 ppm, 95% CI 4.74 to 11.8), compared with normal subjects (n = 37, median 3.0 ppm, 95% CI 2.79 to 3.81, p = 0.0024). There was no correlation between exhaled CO and HbCO levels (r = 0.42, p = 0.12) in normal subjects (n = 7), nor between the urine cotinine concentration and exhaled CO levels (r = 0.2, p = 0.12). Conclusions-Increased levels of exhaled CO may reflect induction of HO-1 and oxidative stress in bronchiectasis. Measurement of exhaled CO may be useful in the management of bronchiectasis and possibly other chronic inflammatory lung disorders.