One breath of air for asthma diagnosis – is that possible?
What do exhaled substances tell about someone’s health status? This is a question that also DZL scientists are posing. They just published results on asthma diagnosis through breath analysis in the European Respiratory Journal. The results were disappointing, but the conclusions are important.
The patient exhales in a tube, the clinical lab analyses ingredient substances, the physician diagnoses. Such a process could be beneficial: the risk of complications inherent to blood drawing or surgical removal of tissue for diagnostic purposes would be reduced. This is one of the reasons why ‘breathomics’ became very popular recently. The relatively new research area deals with exhaled volatile organic compounds (VOCs). The crucial question: is it possible at all to tell just from breath, if someone is ill or healthy? And how can we determine this? Detection methods range from non-technical solutions – such as cancer-sniffing dogs – to electronic noses which allow for live analysis of substance patterns. These experiments are based on the assumption that particularly lung diseases have an impact on breath composition.
Using breath exhalates of 133 patients of the ALLIANCE cohort, DZL researchers tried to discern different asthma subtypes. The disappointing result: none of the VOCs they found gave a statistically significant difference. The results have been published recently in the European Respiratory Journal. Though some earlier studies found differences, the DZL researchers emphasize that breath analysis for asthma – and other diseases – is far from being implemented into clinical practice. First, methodological issues have to be solved and results of research groups have to be validated externally. Dr. Olaf Holz (Fraunhofer-ITEM in Hanover), first author of the paper and dealing with the topic for several years says: “Although we reported ‚negative results‘, the feedback on our paper is tremendous. The question, if detection of exhaled VOCs is ready for the clinic, is important to the community.” There is another possibility for these ‘negative results’: there are really no biomarkers for asthma in exhaled breath. Further studies should clarify this.
Scientists of DZL sites ARCN (LungenClinic Grosshansdorf, University Medical Center Schleswig-Holstein and Pulmonary Research Institute), BREATH (Fraunhofer-ITEM and Medical School Hanover) and CPC-M (Clinic of the Ludwig Maximilians University Munich) collaborated in this study.
DZL is conducting another study on exhaled breath analysis (without looking at VOCs): In EMoLung, researchers intend to predict the course of a lung cancer disease by studying ribonucleic acids.
An established biomarker of exhaled breath is nitric oxide (NO) which indicates inflammation. As its chemical nature is inorganic, NO isn’t considered as VOC.
Source: Holz O*, Waschki B*, Watz H, Kirsten A, Abdo M, Pedersen F, Weckmann M, Fuchs O, Dittrich A-M, Hansen G, Kopp MV, v. Mutius E, Rabe KF, Hohlfeld JM**, Bahmer T** (2020) Breath volatile organic compounds and inflammatory markers in adult asthma patients – negative results from the ALLIANCE cohort. Eur Respir J: 2002127 (ARCN, BREATH, CPC-M)
*,**: shared first or senior authorship, respectively