Several studies using both sensor- and chemical-based platforms have confirmed that exhaled volatile organic compounds (VOCs) are sensitive to underlying inflammation, according to a study published in the European Respiratory Journal.

For this systematic review, researchers utilized a PRISMA‐oriented search of Medline, Embase, and the Cochrane databases for reports that assessed VOCs in patients with asthma who were aged ≥18 years (N=1409). Studies were included if they measured exhaled breath VOCs in a distinct group of patients with asthma. After determining the eligibility of 2957 unique records, researchers selected 66 for full-text review; of these, 22 fulfilled the search criteria and were included in the study.

 The researchers found that there has been rapid technological evolution in the field of asthma VOCs. The majority of modern studies that analyze VOCs use e-nose technology, which is cheaper, quicker, and easier to use than the gold standard of mass spectrometry, but it sacrifices the ability to reliably trace back to the analytes of interest.

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In the relatively new field of breathomics, the researchers found that the sensitivity of exhaled VOCs to underlying inflammation was corroborated across several studies. However, external validation has not yet been met because the discriminatory VOCs used in this study were not the same as those in similar studies nor relevant in in vitro work. Future studies in breathomics should concentrate on standardization of reporting, a more thorough understanding of the best statistical approaches, and access to data-sharing platforms. Study designs that prioritize biomarker discovery could show the full potential of measuring exhaled VOCs in asthma.

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This systematic review had some limitations, including a lack of studies that focused on underlying biology or treatable traits.


Azim A, Barber C, Dennison P, Riley J, Howarth P. Exhaled volatile organic compounds in adult asthma: a systematic review [published online July 4, 2019]. Eur Respir J. doi:10.1183/13993003.00056-2019