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Introduction. Nasal nitric oxide (NO) measurement can be a useful tool for monitoring upper airway diseases. However, there is a considerable lack of validation data. Aims. To evaluate the repeatability and intra-subject variations of nasal NO output ( nV NO ) in healthy adults and to study its correlation with lower airway NO parameters. Methods. nV NO was measured in healthy non-smokers at baseline ( N = 31, age: 28 ± 6 years), after 1 h ( N = 15), 1 d ( N = 15), 1 week ( N = 17), and compared using the Bland-Altman method. At baseline, lower airway NO parameters ( F ENO , flux of NO in the conducting airways and alveolar NO concentration) were also measured and correlated to nV NO (Spearman correlation). Multivariate regression analysis was used to assess the factors influencing nV NO . Results. Baseline median nV NO was 465 (interquartile range (IQR) = 404-536) nL min -1 . The mean differences between the baseline and repeated measurements were not significant ( p > 0.05). The coefficient of repeatability (mean: 118, IQR = 88-181 nL min -1 ) and coefficient of variation (mean: 9.1%) were low. We found no correlation between nV NO and lower airway NO parameters ( p > 0.05). Sex ( β = -0.52, p = 0.02) and body weight ( β = -0.65, p = 0.03) influenced nV NO (model: p = 0.04, R 2 = 0.31). Conclusion. nasal NO output has good repeatability in healthy adults. The NO productions of lower and upper airways are not related in health, but nasal NO output seems to be affected by sex and body weight., (© 2021 IOP Publishing Ltd.)

Objective: Extended nitric oxide (NO) analysis offers the partitioned monitoring of inflammation in central and peripheral airways. Different mathematical models are used to estimate pulmonary NO dynamics in asthma with variable results and limitations. We aimed to establish a protocol for extended NO analysis in patients with differing asthma severity., Methods: Forty patients with stable asthma and 25 matched control subjects were recruited. Exhaled NO was measured at constant flow rates between 10 and 300 mL/s. Twelve controls performed NO measurements weekly for 4 weeks., Results: The proportions of patients with technically acceptable measurements at 10-30-50-100-150-200-250-300 mL/s exhalation flow rates were 8-58-100-98-98-95-90-80%, respectively. Alveolar NO (CANO) and total flux of NO in the conducting airways (JawNO) were calculated with the linear method from NO values measured at 100-150-200-250 mL/s exhalation flows. The mean intrasubject bias for JawNO and CANO in controls was 0.16 nL/s and 0.85 ppb, respectively. Both JawNO (1.31/0.83-2.97/vs. 0.70/0.54-0.87/nL/s, p < 0.001) and CANO (4.08/2.63-7.16/vs. 2.42/1.83-2.89/ppb, p < 0.001) were increased in patients with asthma compared to controls. In patients, CANO correlated with RV/TLC (r = 0.58, p < 0.001), FEF 25-75% (p = 0.02, r = -0.36) and DL,CO (r = -0.46, p = 0.004). JawNO was not related to lung function parameters., Conclusions: Calculation of alveolar NO concentration with the linear method from values obtained at medium flow rates (100-250 mL/s) is feasible even in asthmatic patients with severe airflow limitation and may provide information on small airways dysfunction in asthma.

Electronic noses (e-noses) represent an easy and cheap method for exhaled volatile compound analysis. Various electronic noses are available which differ in material and thus analytical performance. In this review, we describe a wide range of electronic noses and summarize data on the methodological issues in electronic nose research. We also review studies which show the ability of electronic noses to distinguish pulmonary and extrapulmonary disorders from health.

The measurement of the peak exhaled breath temperature (EBT) during multiple tidal breaths offers an easy, non-invasive tool for monitoring airway inflammation. Chronic obstructive pulmonary disease (COPD) is linked to airway inflammation, which is further aggravated by exacerbations of the disease. However, the peak EBT has not been studied in patients with COPD. The breath temperature was measured (X-halo, Delmedica Investments) in 19 control non-smoking subjects (age: 28  ±  11 years, mean ± standard deviation), 19 control smoking/ex-smoking subjects (53  ±  9 years), 20 patients with stable COPD (66  ±  8 years), and 17 patients with COPD at onset and also after recovery from an acute exacerbation (AECOPD; 65  ±  10 years). Spontaneous sputa were collected in AECOPD. The intra-class correlation coefficient of the repeated EBT measurements in non-smokers was 0.87 (95% confidence interval: 0.70-0.95). The peak EBT was different between the subject groups (Kruskal-Wallis test, p = 0.02), with lower values in the patients with stable COPD (34.00/33.35-34.34/°C; median /interquartile range/) than in the smoking/ex-smoking control subjects (34.51/34.20-34.68/°C, p < 0.05). The EBT was higher at the onset of AECOPD (34.58/34.12-34.99/°C, p < 0.05) compared to in a stable condition, and positively correlated with the sputum leukocyte count (p = 0.049, r2 = 0.30; Spearman test) and neutrophil percentage (p = 0.03, r(2) = 0.36). The breath temperature decreased after recovery from AECOPD (34.10/33.72-34.43/°C, p = 0.008; Wilcoxon test). The peak exhaled breath temperature, recorded during multiple tidal breaths, increases with an acute exacerbation of COPD, and may be related to accelerated airway inflammation. The application of exhaled breath temperature measurements when monitoring the activity of COPD should be further assessed in longitudinal studies.

Lung cancer is the leading cause of cancer death. Results of therapeutic interventions are particularly discouraging when the disease is discovered in an advanced stage. Early diagnosis is limited by the fact that the disease usually develops asymptomatically and available screening methods do not fulfil the requirements for reliable discrimination between patients with lung cancer and subjects not suffering from the disease. Breath sampling is completely noninvasive and provides a potentially useful approach to screening lung cancer. Exhaled biomarkers contain both volatile and nonvolatile molecules. The profile of volatile organic compounds is different in patients with lung cancer than in control subjects. In exhaled breath condensate, the proteomic profile of breath from cancer patients differs from that of healthy smokers. We reviewed the scientific evidence demonstrating that a unique chemical signature can be detected in the breath of patients with lung cancer and that the exhaled breath biomarker profile could aid clinical decision making.

Objectives: The effect of hypoxic relapse of chronic obstructive pulmonary disease (COPD) on lung adenosine triphosphate (ATP) concentration was studied measuring ATP in exhaled breath condensate (EBC)., Subjects: Thirty COPD patients with severe exacerbation, thirteen healthy non-smokers and thirteen healthy smokers., Methods: ATP was detected using a luciferin-luciferase assay, dilution of airway droplets in EBC was assessed measuring sample conductivity., Results: ATP concentrations were similar in COPD patients, non-smoking and smoking healthy individuals (141 +/- 44, 115 +/- 21 and 90 +/- 15 pM; p = 0.66). After treatment oxygenation of COPD patients improved (6.85 +/- 1.29 kPa vs. 8.20 +/- 1.28 kPa, p < 0.001), but EBC ATP concentration was similar to that of admission (p = 0.84). There was no correlation between EBC ATP concentration and airway droplet dilution., Conclusion: ATP detected in EBC indicates the presence of ATP in airway lining fluid. Lack of difference in ATP concentration between health and COPD suggests that airway ATP level is under complex control of multiple factors.

Exhaled breath condensate (EBC) pH is considered to reflect the acid-base balance of the airways. Current pH measurements do not take into account the effect of CO2. The aim of the present study was to determine the effect of condensate CO2 partial pressure on pH and to provide a more precise mode of EBC pH determination. Condensate pH and CO2 partial pressure were measured in parallel from 12 healthy volunteers and 12 asthmatics using a blood gas analyser in neat, argon de-aerated and CO2-loaded samples. The regression analysis was used to test the relationship between pH and CO2, and to calculate the pH at a CO2 level of 5.33 kPa (physiological alveolar CO2 partial pressure). Reproducibility of different pH readings was compared using the Bland-Altman test. Condensate CO2 concentration was variable both in neat and argon de-aerated samples. There was a close negative logarithmic relationship between CO2 and pH. Calculation of pH at a CO2 level of 5.33 kPa provided reproducibility approximately six times as good as that of the currently used measurements. Condensate CO2 partial pressure influences pH measurements. Determination of pH at a standard CO2 level provides the most reproducible condensate pH values to date.