Breath gas analysis

Abstract

Exhaled air analyses are an attractive and emerging technology. It is a noninvasive and easy-to-handle method and may especially be suitable for health monitoring under conditions with limited access to standard diagnostic equipment i.e. for extended space missions. Based on the current knowledge together with ongoing and future clinical and space-related-earthbound and on the ISS-research, air analyses might become a suitable tool to monitor the adaption of various physiological systems (immune, organs, metabolism) to the stressful condition in space, thereby helping to assess overall health status as well to establish the diagnosis of diseases. As the concentration of volatile organic and inorganic components in exhaled breath is usually found in the low parts per billion of volume range highly sensitive diagnostic platforms are a prerequisite. These requirements are now met by recent technical improvements leading to an increase in the sensitivity of direct mass spectrometric and gas chromatographic methods. Particular interest is focused to direct mass spectrometric methods as they allow breath-by-breath analyses without evaluation delays. Recent developments in metal oxide sensor technology have awoke the interest in this technology above all due to low energy consumption and maintenance requirements. Furthermore, the recent discoveries of close relationships between specific compounds present in exhaled breath and physiological changes feeds the hope of developing possible noninvasive diagnostic and monitoring tools to diagnose immune dysfunctional states, infections, and cancer. With these recent progresses the technical cornerstone for exhaled breath gas analyses during space missions has been realized. Current research projects focus on the evaluation of exhaled breath gas compound standard values and the impact of stressors in space akin weightlessness, confinement, nutritional changes, hypoxia, and radiation exposure.