The Effects of Age on Exhaled Breath Nitric Oxide Levels

Screening of Obstructive Sleep Apnea Syndrome by Electronic-Nose Analysis of Volatile Organic Compounds

Obstructive Sleep Apnea Syndrome (OSAS) carries important social and economic implications. Once the suspicion of OSAS has arisen, Polysomnography (PSG) represents the diagnostic gold standard. However, about 45% of people who have undergone PSG are free from OSAS. Thus, efforts should be made to improve the selection of subjects. We verified whether the pattern of Volatile Organic Compounds (VOCs) helps to select patients amenable to PSG. We studied 136 subjects (20 obese non-OSAS, 20 hypoxic OSAS, 20 non-hypoxic OSAS, and 20 non-hypoxic Chronic Obstructive Pulmonary Disease (COPD) vs 56 healthy controls) without any criteria of exclusion for comorbidity to deal with a real-life population. VOCs patterns were analyzed using electronic-nose (e-nose) technology. A Discriminant Analysis (Partial Least Square-Discriminant Analysis) was performed to predict respiratory functions and PSG parameters. E-nose distinguished controls (100% correct classification) from others and identified 60% of hypoxic, and 35% of non-hypoxic OSAS patients. Similarly, it identified 60% of COPD patients. One-by-one group comparison yielded optimal discrimination of OSAS vs controls and of COPD vs controls (100% correct classification). In conclusion, e-nose technology applied to breath-analysis can discriminate non-respiratory from respiratory diseased populations in real-life multimorbid populations and exclude OSAS. If confirmed, this evidence may become pivotal for screening purposes.

Reference value of induced sputum cell counts and its relationship with age in healthy adults in Guangzhou, Southern China

PURPOSE

To establish the reference value of total and differential cell counts in induced sputum in healthy adults in Guangzhou, and to explore the relationship of age and gender with sputum cell counts.

METHODS

A total of 185 healthy, nonatopic, never-smokers between 19 and 74 years old underwent induced sputum test with hypertonic saline (3%) inhalation. Sputum samples were collected for total and differential cell counts.

RESULTS

Qualified sputum samples were obtained from 153 subjects (mean age: 43 ± 17) with a success rate of 82.7% (153/185). The mean Standard Deviation (STDEV) and 2.5% to 97.5% percentile total cell counts were 2.1 × 106/g (1.0), (.7-4.5 × 106/g). The mean STDEV and 2.5% to 97.5% percentile differential cell counts were as follows: neutrophil 38.3% (17.7), (8.9%-72.9%); macrophage 58.9% (17.7), (24.7%-90.0%); eosinophils: median, .3%; interquartile range (IQR), 1.1%; and .0% to 95.0% percentile, .0% to 2.0%; and lymphocytes: median, 1.0%; IQR, 1.8%; and .0% to 95.0% percentile, .0% to 4.5%. There was positive correlation of age with the percentage of neutrophil and eosinophil (r = .659, r = .402; P < .001). The percentage of neutrophil, macrophage and eosinophil were significantly different among different age groups. The total cell counts and sputum cell counts were comparable between males and females.

CONCLUSIONS

This study initially establishes reference value of induced sputum cell counts in healthy adults in Guangzhou, Southern China, and it verifies that neutrophilic and eosinophilic counts increase by age.

Evolution of exhaled nitric oxide levels throughout development and aging of healthy humans

It is not fully understood how the fraction of exhaled nitric oxide (FeNO) varies with age and gender in healthy individuals. We aim to describe the evolution of FeNO with age, giving special regard to the effect of gender, and to relate this evolution to natural changes in the respiratory tract.We studied 3081 subjects from NHANES 2007-08 and 2009-10, aged 6-80 years, with no self-reported diagnosis of asthma, chronic bronchitis or emphysema, and with normal values of blood eosinophils and C-reactive protein. The relationship of the mean values of FeNO to age, in all participants and divided by gender, was computed, and compared with changes in anatomic dead space volume and forced vital capacity. A change-point analysis technique and subsequent piecewise regression was used to detect breakpoints in the evolution of FeNO with age.Three distinct phases in the evolution of FeNO throughout the age range 6-80 years can be seen. FeNO values increase linearly between 6-14 years of age in girls and between 6-16 years of age in boys, in parallel with somatic growth. After that, FeNO levels plateau in both genders until age 45 years in females and age 59 years in males, when they start to increase linearly again. This increase continues until age 80.Our data clearly show a triphasic evolution of FeNO throughout the human age range in healthy individuals. This should be accounted for in development of reference equations for normal FeNO values.

Exhaled breath analysis by electronic nose in respiratory diseases

Breath analysis via electronic nose is a technique oriented around volatile organic compound (VOC) profiling in exhaled breath for diagnostic and prognostic purposes. This approach, when supported by methodologies for VOC identification, has been often referred to as metabolomics or breathomics. Although breath analysis may have a substantial impact on clinical practice, as it may allow early diagnosis and large-scale screening strategies while being noninvasive and inexpensive, some technical and methodological limitations must be solved, together with crucial interpretative issues. By integrating a review of the currently available literature with more speculative arguments about the potential interpretation and application of VOC analysis, the authors aim to provide an overview of the main relevant aspects of this promising field of research.

Aging and airway inflammation

BACKGROUND

Since little is known of airways inflammation in the elderly, we have carried out a study to explore the presence of some inflammatory markers in the airways of healthy subjects of different ages using a non-invasive method which is particularly suitable for aged people.

OBJECTIVE

The aim of this work was to investigate whether parameters, including (1) pH, IL-8 and TNF-α in exhaled breath condensate (EBC), (2) exhaled nitric oxide levels (NO), and (3) inflammatory cell profile in induced sputum, are age-related.

MATERIALS AND METHODS

Thirty healthy adults (10 subjects below the age of 30 [A], 10 subjects between 30 and 60 years [B], and 10 subjects over 60 years of age [C]), were enrolled in the study. IL-8 and TNF-α levels were measured in breath condensate. Exhaled pH was measured after deaeration/decarbonation by means of a pH-meter. A rapid-response chemiluminescence NO analyzer was used to quantify NO. Induced sputum was collected, homogenized with dithiothreitol, and cytospins for differential cell were produced.

RESULTS

The levels of IL-8 and TNF-α in EBC, the levels of exhaled NO, and the percentage of neutrophils in induced sputum were significantly elevated in C and B compared with A; the EBC pH level was significantly reduced in C and B compared with A. The EBC levels of IL-8, TNF-α, pH, the level of exhaled NO, and the percentage of neutrophils correlated significantly with age.

CONCLUSION

This study has shown the presence of age-related airways inflammation in healthy subjects.

Reference values and determinants of exhaled nitric oxide in healthy Korean adults

BACKGROUND

Measuring fractional exhaled nitric oxide (FeNO) provides an indication of airway inflammation and is used as an inflammatory marker for asthma management. However, reference values and determinants of FeNO levels are not well defined in healthy Asian adults. This study aimed to establish FeNO reference values in nonsmoking, healthy Asian adults and to determine the factors related to FeNO levels.

METHODS

The authors measured FeNO in 166 nonsmoking, healthy Korean adults and collected data regarding factors possibly associated with FeNO, including age, height, weight, and respiratory symptoms. Lung function was measured using spirometry, and atopic status was determined based on the skin-prick test.

RESULTS

In a multivariate linear regression analysis, FeNO levels were positively associated with male gender (p = .008) and atopy (p = .044) after adjusting for age, height, weight, forced expiratory volume in one second (FEV(1)), and chronic rhinitis. Reference values were presented according to gender and atopic status, and the mean FeNO value was highest in male atopic subjects (37.3 +/- 12.1 ppb), followed by nonatopic males (33.9 +/- 14.3 ppb), atopic females (28.6 +/- 17.7 ppb), and nonatopic females (24.1 +/- 10.6 ppb). In healthy Korean adults, FeNO levels showed a significant and independent association with male gender and atopy.

CONCLUSIONS

We believe that the presented FeNO reference values and the determining factors could be useful for research and clinical practice in the adult Asian population.

Inflammation and airway function in the lung periphery of patients with stable asthma

BACKGROUND

An important role for exhaled nitric oxide (NO) measurement could be in the distinction between proximal and peripheral lung contributions to inflammation, with a particular interest for the alveolar lung zone and its implication on airway function.

OBJECTIVE

We aimed to isolate the acinar lung zone contribution to both inflammation and airway function to seek a relationship between them.

METHODS

In 30 patients with asthma with an asthma control test score exceeding 20, indices of conductive and acinar ventilation heterogeneity (Scond, Sacin) were obtained from a multiple breath washout. NO production in the conductive airways (J'aw(NO)), alveolar NO concentration (CA(NO)), and the standard exhaled NO at 50 mL/s (FENO(50)) were obtained from exhaled NO.

RESULTS

Scond was consistently abnormal in all patients with stable asthma, but without any correlation to inflammation abnormality in that compartment (J'aw(NO)). Sacin was particularly abnormal in the asthma subgroup receiving >500 microg budesonide equivalent, and a correlation was found between Sacin and CA(NO) (r = 0.61; P = .015); in this subgroup, a weak association was found between Scond and J'aw(NO) or FENO(50) (r = 0.50; P = .059 for both).

CONCLUSION

The persistent functional abnormality of small conductive airways in patients with stable asthma is largely independent of inflammation as measured by exhaled NO. In the alveolar compartment, a functional correlate of alveolar NO was found in a subgroup of patients with stable asthma on moderate-to-high maintenance doses of inhaled steroids. These patients in particular could benefit from novel therapies specifically aimed at improving airway functionality at the level of the acinar entrance and beyond.

Fraction of exhaled nitric oxide at 50 mL/s: reference values for adult lifelong never-smokers

BACKGROUND

The measurement of fractional exhaled nitric oxide (FENO) is used as a marker of airway inflammation. The aim of this study was to establish reference values of FENO for adults.

METHODS

FENO at a flow rate of 50 mL/s was analyzed in 3,376 adults using a chemiluminescence analyzer according to American Thoracic Society/European Respiratory Society guidelines. Blood samples were analyzed, and atopy was defined as the presence of specific IgE. All subjects responded to a respiratory questionnaire. Those who had never smoked (n = 1,803) were selected for this study. After the exclusion of subjects with physician-diagnosed asthma, asthma symptoms, ever wheezing, dry cough, or use of inhaled steroids, 1,131 healthy never-smokers remained, including 845 nonatopic and 286 atopic subjects.

RESULTS

Based on multiple regression modeling, we propose the following reference equation for healthy never-smoking adults: Ln(FENO) = 0.057 + 0.013 x height (in centimeters) + 0.0088 x age (in years). The residual SD was 0.51, and the explanatory value was 9%. In a model, based on nonatopic subjects alone, the reference equation obtained was slightly different, as follows: Ln(FENO) = -0.0026 + 0.013 x height (in centimeters) + 0.010 x age (in years). The residual SD for this equation was 0.48, and the explanatory value was 11%.

CONCLUSIONS

Normal values of FENO for adults may be predicted on the basis of age and height. However, as the reference equations only account for about 9 to 11% of the variation, the most important information that could be extracted from the study is that the upper limits of FENO range from 24.0 to 54.0 parts per billion, depending on age and height.

Nitric Oxide and Exhaled Breath Nitrite/Nitrates in Chronic Obstructive Pulmonary Disease Patients

BACKGROUND

Measurement of nitric oxide (NO) and nitrite/nitrates (NOx) levels in exhaled breath condensate (EBC) are non-invasive techniques, which can be used to monitor airway inflammatory diseases. Production of NO is often increased in inflammatory diseases of the airways, including exacerbations of chronic obstructive pulmonary disease (COPD). COPD-associated airway inflammation may be affected by multiple factors, including cigarette smoking and glucocorticosteroid (GCS) treatment.

OBJECTIVES

To test the hypothesis that total NOx levels in EBC and exhaled NO levels would be affected by cigarette smoking or the presence of COPD.

METHODS

Exhaled NO levels and NOx levels in EBC were measured in 96 COPD patients and in 80 normal subjects.

RESULTS

Exhaled NO levels in COPD patients were significantly higher than those of normal subjects when comparing either the total groups (9.8 +/- 0.7 vs. 5.5 +/- 0.4 ppb, p < 0.0005) or 2 appropriate subgroups, ex-smokers (10.3 +/- 1.0 vs. 5.4 +/- 0.6 ppb, p < 0.0005) and smokers (9.2 +/- 1.2 vs. 5.7 +/- 0.5 ppb, p = 0.002). There was no significant difference in NOx levels in EBC, however, between COPD patients and healthy subjects when analysed either together or as subgroups. No significant difference was found in either exhaled NO levels or NOx levels in EBC between GCS-naive subjects and those on GCS treatment in the ex-smoking or smoking COPD subgroups.

CONCLUSIONS

COPD patients have higher exhaled NO levels than control subjects when either combined or analysed as non-smoking, ex-smoking and smoking subgroups. GCS treatment did not appear to affect these non-invasive markers of airway inflammation in COPD.