Pathophysiology of Adult OSA: A Dynamic Look to Upper Airway Obstruction

The pathophysiological mechanism underlying the upper airways obstruction has underlined the relevance of airflow waves analysis during nocturnal diagnostic examination in order of better phenotyping Osbtructive Sleep Apnea subjects. The use of nasal cannulas during nocturnal polysomnography or cardiorespiratory monitoring to detect the airflow of patients with obstructive sleep apnea allows detecting a semiquantitative airflow shape; this gives us the possibility to analyze the morphology of airflow shape during regular and partial upper airway obstruction, to obtain pieces of information on upper airway morphology during the whole respiratory cycle. The analysis of the different airflow shapes during the night provides information on the different sites of the upper airway obstruction (palate, tongue, pharynx, and epiglottis) also concerning the body position or the sleep stage. The articles taken into account in this review actively contributed to clarifying this connection. Therefore, the airflow analysis recorded with the nasal cannulas can be used as an inexpensive and noninvasive tool to phenotype the patients and optimize the therapeutic approach by identification of pharyngeal structure that causes collapse during spontaneous sleep.