Interpretation of exhaled volatile organic compounds

It is current opinion that the composition of breath contains information which enables the detection of a number of different diseases. Even if there is no clear explanation about the connection between diseases and volatile compounds, several studies involving instruments, such as gas chromatography and electronic nose, have provided evidence that in the case of certain diseases it is possible to correctly identify the breath of patients with respect to the breath of healthy individuals. Most of these studies are focused on lung cancer.Correct interpretation of the results from these studies requires medical and instrumental consideration of the problem. The medical approach has to consider the bio-chemical processes that connect the disease to the production of small volatile molecules which can be found in breath. These molecules are revealed by instrumental analyses. Following this, volatile organic compounds are detected by the interaction between the molecules in the exhaled breath and the sensors. This interaction is a transduction operation ruled by three fundamental instrumental characteristics: working principle, selectivity and sensitivity. In this chapter the complete interpretation procedure is viewed as a short review of the medical interpretation of the volatile organic compounds in exhaled breath and the related diseases.