Many abnormalities of the nose and pharynx can cause or aggravate snoring and sleep apnea. Nasal septal deviation, nasal polyps, inferior turbinate hypertrophy and rhinitis can cause nasal airway obstructions. Adenoid hypertrophy, nasopharyngitis and nasopharyngeal tumors can cause nasopharyngeal airway narrowing (6).Epidemiological studies have found relationships between a history of nasal stuffiness and snoring (8) and between measured nasal airflow and a history of snoring (3), but attempts to find a linear correlation between nasal obstruction and sleep-disordered breathing have been less successful (2,30,34). However, a weak correlation between nasal resistance measured by means of posterior rhinomanometry and the severity of sleep apnea has recently been reported (15).Several studies have shown that increased nasal resistance may induce sleep-related breathing disorders (SRBD) and cause disturbed sleep (7, 8); however, contradictory results have also been obtained (12).
PathophysiologyThree interacting factors play a critical role in obstruction of the upper airway in OSAS: the muscle activity of the dilators of the pharyngeal airway, the negative pressure generated during inspiration, which opposes the activity of the dilators, and the structural anatomy of the airway (7, 31).Mouth opening, independent of the breathing route, is believed to increase the collapsibility of the upper airways as a result of a decrease in the contractility of the upper airway muscles (20).The biologic basis for nasal obstruction as a cause of sleep-disordered breathing lies in the effect of nasal breathing on resistance and flow velocity, which affects the pressure differential between the atmosphere and the intrathoracic space (34). Partial or complete obstruction can occur when the intrathoracic negative pressure generated by the inspiratory muscles pulls on the compliant soft tissue in the upper airway, sucking the airway closed (26). It is worth pointing out that the nose accounts for half of the total respiratory system resistance (24). Nasal obstruction leads to various breathing disturbances, including an increase in sleep apnea-hypopnea and a reduced nocturnal lowest SpO 2 (23, 33).Although the primary site of obstruction in patients with OSAS is believed to be the oropharyngeal-hypopharyngeal region (Fig. 1), numerous studies examining the effects of experimentally-induced nasal obstruction on OSAS have indicated a positive and significant association (7,23,32,36). Therefore, nasal obstruction constitutes a predisposing factor for OSAS (1,3,23,32,36). Effects of nasal pathologies on OSA are summarized in Fig. 2.
Effects of Allergic Rhinitis on OSAThe prevalence rate of allergic rhinitis is increasing by 3.5 % per decade and is estimated to be 15-25 % in Europe (29).In general, allergic rhinitis constitutes a pathologic condition characterized by a transient increase in nasal airway resistance due to mucosal swelling (16,18,22,25) and therefore theoretically constitutes a risk factor for OSAS.Several reports in which ...
