Hyperbaric oxygen diving affects exhaled molecular profiles in men.

Exhaled breath contains volatile organic compounds (VOCs) that are associated with respiratory pathophysiology. We hypothesized that hyperbaric oxygen exposure (hyperoxia) generates a distinguishable VOC pattern. This study aimed to test this hypothesis in oxygen-breathing divers. VOCs in exhaled breath were measured in 10 male divers before and 4h after diving to 9msw (190kPa) for 1h. During the dive they breathed 100% oxygen or air in randomized order. VOCs were determined using two-dimensional gas chromatography with time-of-flight mass spectrometry. Compared to air dives, after oxygen dives there was a significant increase in five VOCs (predominately methyl alkanes). Furthermore, a strong, positive correlation was found between increments in 2,4-dimethyl-hexane and those of 4-ethyl-5-methyl-nonane. Although non-submerged hyperoxia studies on VOCs have been performed, the present study is the first to demonstrate changes in exhaled molecular profiles after submerged oxygen diving. The pathophysiological background might be attributed to either a lipid peroxidation-induced pathway, an inflammatory pathway, or to both.