The search for volatile organic compounds in breath as biomarkers for pulmonary oxygen toxicity in divers

This thesis builds on prior research into pulmonary oxygen toxicity (POT), focusing on detecting volatile organic compounds (VOCs) as biomarkers using gas chromatography-mass spectrometry (GC-MS). The main goal is identifying VOCs linked to POT after prolonged hyperbaric and hyperoxic exposures to establish reliable biomarkers in exhaled breath.
In two studies (Chapters 2 and 3), subjects underwent "dry" hyperbaric exposures with high partial pressures of oxygen. In Chapter 2, following a TT6 treatment involving 100% oxygen at 283 kPa for nearly 5 hours, eleven VOCs were detected, with significant changes in five: isoprene, decane, nonane, nonanal, and dodecane. No POT symptoms were reported. Chapter 3 involved a COMEX-30 treatment table with exposures up to 405 kPa for 7.5 hours using an oxygen/helium mix. Nine VOCs were identified, four showing significant increases. Mild POT symptoms were reported in seven out of ten subjects.
Chapter 4 pooled data from these and three previous studies to create the VAPOR library, cataloguing 29 VOCs linked to hyperbaric and hyperoxic exposures. Chapter 5 describes a field study on operational diving, identifying similar VOCs, validating the feasibility of breath sampling during dives. Chapter 6 presents an in vitro study using alveolar cells exposed to hyperbaric oxygen similar to the study from chapter 2, identifying three VOCs, suggesting this model's potential for further research.
In conclusion, various VOCs linked to POT were identified. Although no single VOC was consistently found in all studies, there was significant overlap in the VOCs detected, with most being (methyl) alkanes and aldehydes.