Diagnostic potential of breath analysis – Focus on the dynamics of volatile organic compounds

Analysis of exhaled volatile organic compounds (VOCs) holds promise for the development of new and non-invasive procedures in many areas of clinical and home care applications. Recent research mainly focused onto cross-sectional pilot studies with single point measurements in order to detect specific VOC markers or marker sets for diseases such as cancer, infections or diabetes. Actual studies have shown the highly dynamic behavior of exhaled VOC profiles related to factors such as exposure, nutrition, exercise, medication but also to physiology and clinical interventions. Single point analyses cannot take into account neither the fundamentally dynamic nature of exhaled substance profiles nor can they sufficiently reflect the kinetics of exogenous contaminants and confounders and are, therefore, prone to erroneous interpretation, especially if single point analyses are applied for primary diagnostic purposes. These disadvantages cannot be overcome by means of any statistics as complex and sophisticated these algorithms may be. While unique VOC markers for certain diseases could not be confirmed in independent studies, analytical techniques and tools to identify and monitor VOCs as well as the knowledge on exhaled VOCs have developed significantly during the last two decades of breath research. As dynamic VOC profiling provides valuable information on kinetics of markers and confounders, it offers huge and so far unexplored potential for physiological, metabolic, therapeutic and environmental monitoring. Driven by new and innovative technologies such as real time mass spectrometry and highly specific sensor systems, future applications may range from home care to ICU monitoring. • Breath analysis provides insights into human physio-metabolic as well as pathophysiological processes through a noninvasive window. • A unique feature of VOC emission from living organisms is the highly dynamic and quickly changing nature of breath composition. • Single point breath analyses can not take into account the dynamic nature of exhaled VOC profiles or reflect the kinetics of exogenous confounders. • Dynamic VOC profiling provides kinetic information of markers and confounders and towards physico-metabolic, therapeutic and environmental monitoring. • Driven by innovative technologies such as real time MS and specific sensors , future applications may range from homecare to ICU monitoring.