Negative expiratory pressure is a technique that has been the focus of many studies in the last few years.

Airway response to the application of a negative expiratory pressure (NEP) can be used to detect the presence of upper airway collapsibility. In normal subjects, an increase in expiratory flow is observed while in patients with collapsible upper airway, the flow will show a transient decrease due to airway collapse.

The objectives of this study will be initially to investigate the diagnostic utility of this technique as a noninvasive measurement of the stability of the upper airway in sleep-related breathing disorders. Secondly, we aim to see the sites of airway obstructions, discovered by NEP, through nasal endoscopy. Finally, we aim at testing the utility of NEP technique in the evaluation of therapeutic response. For this purpose, we will apply it in patients before and after airway stabilization interventions like ENT surgery, oropharyngeal exercises, orthodontic mandibular advancement electrical stimulation of the hypoglossal nerve.

Inclusion Criteria:

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Exclusion Criteria:

• Patients with COPD