Exhaled breath analysis by real-time MS in patients with pulmonary fibrosis
P. M-L Sinues, Y. Nussbaumer Ochsner, M.T. Gaugg, L. Bregy, A. Engler, R. Zenobi, M. Kohler.
Introduction: Idiopathic pulmonary fibrosis (IPF) is recognized as a distinct clinical disorder. However, despite major endeavors to understand the pathogenesis, the diagnosis of IPF remains elusive. Metabolic profiling of biopsied tissue specimens has been shown promise to gain insights into IPF pathogenesis. Thus we hypothesized that analysis of exhaled metabolites may also provide further insights.
Methods: 21 patients with IPF and 21 matched controls were recruited for this exploratory study. Exhaled breath analysis was performed by Secondary Electrospray Ionization-Mass Spectrometry (SESI-MS). Significant differences in exhaled metabolite levels in IPF were subsequently sought. A two-sample t-test followed by estimation of false discovery rate in multiple comparisons was used for this purpose. Statistical significance was set at p < 0.05. Finally, we attempted to predict IPF vs control in a leaveone- out-cross-validation (LOOCV) using a set of 15 metabolites per sample predicted.
Conclusions: Analysis of exhaled breath by real time mass spectrometry shows promise to help in the diagnostic process of IPF. Breath analysis complements ongoing efforts to characterize IPF at the metabolic level using more invasive approaches (e.g. biopsy). Ongoing in-depth structural identification of altered breath metabolites is likely to provide insights on IPF pathogenesis. These findings will require further validation in larger and independent cohorts.