Breath gas analysis
[1] VOCs in exhaled breath can represent biomarkers for certain pathologies (lung cancer, asthma, chronic obstructive pulmonary disease and others).
Research on exhaled breath started many years ago, there is currently limited clinical application of it for disease diagnosis.
For example, it was believed that the exhaled breath of a diabetes person presented a sweet odor, while for people affected by kidney failure it showed a fish-like smell.
[5] Only with Antonie Lavoisier, the pure smelling of human exhaled breath was substituted by a systematic analysis of the chemical contents.
[7] In recent years, many scientists have focused on the analysis of exhaled breath with the aim of identifying disease-specific biomarkers at early stages.
Even though exhaled breath analysis started many years ago, there is still no clinical application of it for disease diagnosis.
[10][11][12] Though the use of so-called breath-prints, determined by electronic noses, are promising and seem to be able to distinguish between lung cancer, COPD, and asthma.
Moreover, future applications for medical diagnosis and therapy control with dynamic assessments of normal physiological function or pharmacodynamics are intended.
These factors are related to both the breath sampling protocols as well as the complex physiological mechanisms underlying pulmonary gas exchange.
Understanding the influence of all the factors and their control is necessary for achieving an accurate standardization of breath sample collection and for the correct deduction of the corresponding blood concentration levels.
Furthermore, breath profiles of acetone (and other highly soluble volatile compounds such as 2-pentanone or methyl acetate) associated with moderate workload ergometer challenges of normal healthy volunteers drastically depart from the trend suggested by the equation above; hence some more refined models are necessary.
Some examples of breath collection tools used across the research industry for VOC analysis are: These devices can be used as a vehicle for direct introduction of a gas sample into an appropriate analytical instrument, or serve as a reservoir of breath gas into which an absorption device such as an SPME fiber is placed to collect specific compounds.
Analyzing breath in real-time has the advantage that potential confounding factors associated with sample handling and manipulation are eliminated.
Recent efforts have focused on standardizing online breath analysis procedures based on SESI-MS, and to systematically study and reduce other confounding sources of variability.
[28] Breath analysis can be done with various forms of mass spectrometry, but there are also simpler methods for specific purposes, such as the Halimeter and the breathalyzer.
