Applications and challenges of exhaled volatile organic compounds in critically ill patients

Early detection of critical illness is essential for timely intervention and improved outcomes. Conventional diagnostic methods, such as laboratory tests and imaging, are invasive and often delayed. In recent years, non-invasive monitoring approaches, particularly exhaled breath analysis, have gained attention in critical care. Various analytical platforms, including gas chromatography-mass spectrometry, proton transfer reaction mass spectrometry, and electronic nose systems, have been employed to identify volatile organic compound (VOC) patterns associated with acute conditions. Elevated aldehydes and ketones have been reported in ventilator-associated pneumonia, hydrocarbons such as octane in acute respiratory distress syndrome, and acetone in acute heart failure. These findings highlight the value of VOC-based approaches for early disease recognition, pathogen identification, and dynamic monitoring at the bedside. Exhaled breath analysis represents a promising, non-invasive tool to complement conventional diagnostics in the intensive care unit, though challenges such as standardization and large-scale validation remain. This review focuses on the application of VOCs in the management of critically ill patients, with special emphasis on their diagnostic and monitoring potential.