Identification of volatile organic compounds in breath associated with liver disease and their potential applications for medical use

Proton Transfer Reaction Mass Spectrometry (PTR-MS) was applied to determine which volatile organic compounds in breath are associated with cirrhosis and hence diagnostically useful. A two-stage biomarker procedure was used. In the first-stage, alveolar breath samples of 31 cirrhotic patients and 30 controls were analysed and compared. In the second-stage, 12 of the patients had their breath analysed after liver transplant. The first-stage study showed that seven volatiles were elevated in patients’ breath compared to controls. Of these, limonene, methanol, 2-pentanone showed a statistically significant decrease post-transplant and hence can unequivocally be used as biomarkers for chronic liver disease. Limonene which is not produced in the body showed washout characteristics and the best diagnostic capability. These findings suggest that limonene, methanol and 2-pentanone are potential biomarkers for early-stage liver disease. Limonene was detected in higher levels in patients with symptoms of hepatic encephalopathy (HE) in comparison to those with no symptoms. Limonene discriminates patients suffering from HE, but not methanol or 2-pentanone. The elimination characteristics of post-operative isoflurane levels in breath of 5 patients were investigated. High concentrations of isoflurane remained in their breath for several weeks. This study raises the question about the effect of isoflurane in the neurocognitive function of patients after major surgery