Exhaled volatile organic compounds (VOCs) for prediction of asthma exacerbation in children

Objectives To find possible relationship between asthma exacerbation and metabolomic profile of airways, assessed by non-invasive method – free volatile organic compounds (VOCs) in exhaled air in children. Material and Methods The study included 80 children aged 4–18 years with asthma: 42 children with a min. 3 asthma exacerbations in the past 12 months, and 38 children without a history of exacerbations in the past year. During the study visit, each patient was examined, medical history (including information regarding atopy and eosinophil blood count) was taken, spirometry and fractional exhaled nitric oxide (FeNO) were tested, an exhaled air sample was taken to test for the presence of VOCs, and the patient also completed standardized form – Asthma Control Questionnaire. Volatile organic compounds were measured by combined gas chromatography coupled to mass spectrometry. Results The obtained results of VOCs were correlated with the history of the disease. The 2 gas profiles were defined and they formed 2 clinically distinct clusters (p = 0.085). Cluster 2 was characterized for children with a higher number of bronchial asthma exacerbations and worse lung function parameters (predicted percentage forced expiratory volume in 1 s [FEV1] [p = 0.023], FEV1/ forced vital capacity ratio [FVC] [p = 0.0219]). The results were independent of the age, sex, BMI, atopy (house dust mite allergy) and eosinophil blood count. Conclusions The study findings suggest that a relative group of gases may be a useful predictor of having asthma exacerbations in children. Additionally, a single FeNO value was unlikely to be clinically useful in predicting asthma exacerbations in children. The VOCs profile reflecting the metabolism of the airway epithelium and local microbiota was associated with the course of asthma, which strongly justifies further prospective validation studies.