Table 1.

Nasal pathophysiology in the pathogenesis of OSAS.

Starling resistor model	Increased nasal resistance results in negative oropharyngeal pressure (suction force).
Instability of mouth breathing	Significant increase in nasal resistance generates higher fraction of oral breathing, leading to unstable airway.
Nasal ventilatory reflex	Decrease in nasal airflow results in less activation of nasal receptors and, consequently, inhibition of muscle tone, respiratory rate, and minute ventilation.
Nitric oxide (NO)	Decrease in nasal flow generates lower concentration of pulmonary NO with reduced ventilation-perfusion ratio.