Introduction: Although OSA is considered a major public health issue, metabolic consequences of different OSA phenotypes are still unknown. Previous studies using breath analysis to evaluate metabolic consequences of OSA suggested disease specific changes of molecular breath prints upon CPAP withdrawal, but were limited by their short follow-up and sample size. (Schwarz, E.I. et al. Thorax 2016; 71(2):110-7)

Aims and objective: The objective of this prospective study was to determine changes in molecular breath patterns in newly diagnosed OSA patients before and after at least one month of CPAP therapy by untargeted, secondary electrospray ionization-high resolution mass spectrometry (SESI-HRMS).

Methods: Symptomatic OSA patients (ESS?10, AHI?15/h) were recruited at the University Hospital Zurich. SESI-HRMS was used to collect and analyze patients? alveolar breath in real-time.

Results: The breath prints of 50 patients (3 drop outs) were analyzed (82% male, mean [SD] age 49 [11.8] years, BMI 34.8 [7.2] kg/m2). Median [quartiles] AHI and ODI were 33.8 [25.1, 56.1] and 30.5 [21.2, 41.0] events/h. Six patients did not use their CPAP, the remainder showed a median [quartiles] hour usage of 4.1 [1.3, 5.9] h/night and a usage of 87 [48, 97] % of all nights. Multiple breath features (putative biomarkers for OSA) showed evidence for a change upon CPAP initiation.

Conclusion: Breath analysis by SESI-HRMS is feasible to detect OSA specific breath features upon initiation of CPAP therapy. The dataset is now further analyzed to identify breath signals correlating with other clinical characteristics and phenotypes.