Relationship between lung function and exhaled volatile organic compounds in healthy infants

Abstract

Objective: The aim of this study is to assess, for the first time, the relationship between the volatilome and lung function in healthy infants, which may be of help for the early detection of certain respiratory diseases. Lung function tests are crucial in chronic respiratory diseases diagnosis. Moreover, volatile organic compounds (VOCs) analysis in exhaled breath is a noninvasive technique that enables the monitorization of oxidative stress, typical of some forms of airway inflammation.

Methods: Lung function was studied in 50 healthy infants of 3-8 months of age and the following parameters were obtained: forced vital capacity (FVC), forced expiratory volume at 0.5 s (FEV_0.5 ), forced expiratory flow at 75% of FVC (FEF₇₅ ), forced expiratory flow at 25%-75% of FVC (FEF_25-75 ), and FEV_0.5 /FVC. Lung function was measured according to the raised volume rapid thoracoabdominal compression technique. In addition, a targeted analysis of six endogenous VOCs (acetone, isoprene, decane, undecane, tetradecane, and pentadecane) in the exhaled breath of the children was carried out by means of thermal desorption coupled gas chromatography-single quadrupole mass spectrometry system.

Results: A negatively significant relationship has been observed between levels of acetone, tetradecane, and pentadecane in exhaled breath and several of the lung function parameters. Levels of acetone (feature m/z = 58) were significantly negatively associated with FVC and FVE_0.5 , levels of tetradecane (feature m/z = 71) with FEV_0.5, and levels of pentadecane (feature m/z = 71) with FEV_0.5 and FEF_25-75 .

Conclusion: The findings of this study highlight a significant association between VOCs related to oxidative stress and lung function in healthy infants.

Keywords: early respiratory diseases detection; exhaled breath analysis; infant lung function; monitorization of oxidative stress; volatile organic compounds.

Figure 1

Z‐scores for lung function parameters determined in infants. Red lines indicate the upper and lower limit of the normal range (±1.96 z‐scores). FEF_25–75, forced expiratory flow at 25%–75% of FVC; FEF₇₅, forced expiratory flow at 75% of FVC; FEV_0.5, forced expiratory volume at 0.5 s; FVC, forced vital capacity [Color figure can be viewed at wileyonlinelibrary.com]

Figure 2

Significant correlations between lung function parameters (z‐score) and features of volatile organic compounds determined in exhaled breath of infants. FEF_25–75, forced expiratory flow at 25%–75% of FVC; FEV_0.5, forced expiratory volume at 0.5 s; FVC, forced vital capacity [Color figure can be viewed at wileyonlinelibrary.com]

Figure 3

Principal component analysis (PCA) was performed on the lung function parameters in infants. (A) Biplot of the first two components. The purple vectors correspond to the variables involved in the PCA. (B) Negative significant correlations between the first component, and tetradecane (feature m/z = 71) and pentadecane (feature m/z = 71) were determined in the exhaled breath of the infants. (C) Contribution of the variables in the first component. FEF_25–75, forced expiratory flow at 25%–75% of FVC; FEF₇₅, forced expiratory flow at 75% of FVC; FEV_0.5, forced expiratory volume at 0.5 s; FVC, forced vital capacity [Color figure can be viewed at wileyonlinelibrary.com]

Figure 4

Oxidative stress monitoring by volatile organic compounds analysis in exhaled breath. PUFAs, polyunsaturated fatty acids [Color figure can be viewed at wileyonlinelibrary.com]