The current view foresees that airway inflammation and oxidative stress are both important in the pathophysiology of obstructive sleep apnea syndrome (OSAS). Notwithstanding the fact that these events play a key role in OSAS, their monitoring is not included in the current management of this disease.

The direct sampling of airways is made possible today thanks to what can be defined as quite invasive techniques, such as bronchoscopy with broncho-lavage and biopsy. Recently there has been increasing interest in the non-invasive methods that allow the study of airways via the induced sputum (IS), the exhaled breath volatile mediators and the exhaled breath condensate (EBC). The non-invasiveness of these techniques makes them suitable for the evaluation and serial monitoring of OSAS patients. The aim of this review is to spread current knowledge on the non-invasive airway markers and on their potential clinical applications in OSAS.