Comparative analysis of gases exhaled in breath and dissolved in blood: development of a novel blood degassing apparatus

While several breath gases have been associated with various diseases, their potential as biomarkers remains inconclusive, partly due to their unclear origin within biological systems. Identifying the presence/concentration of exhaled gases in the bloodstream could significantly advance the field; this has been attempted with headspace measurement of cultured blood, a technique prone to contamination, loss and incomplete release of gases. Therefore, no systematic chemical comparison of breath and blood gas composition is yet available. We developed a novel apparatus that can completely degas blood via a flow of helium microbubbles, eliminating thermo‐purging/anti‐foaming agents necessary for headspace measurements. The apparatus was used in this study to chemically compare blood and breath gas composition in 4 healthy males (27±2 yrs). Of the 75 compounds analyzed with gas chromatography, 18 representative gases were selected; 9 were found only in blood, 3 only in breath, and 6 in both, but at markedly different concentrations (see Figure). Our data suggest a complex interaction between peripheral tissue gas production and gas concentrations in exhaled breath. Further clarification of all components of this interaction may help optimize the use of breath analysis as a diagnostic or monitoring tool in a variety of conditions, through the development of non‐invasive, portable breath‐testing device. Support: NIH grant 1UL1RR031985; ADA #7‐08‐CR‐22