Influence of postural changes on nasal resistance in patients with obstructive sleep apnea.

Objective: Increased nasal resistance (NR) can augment upper airway collapse in patients with obstructive sleep apnea (OSA). Posture change can lead to altered nasal resistance. Our study aimed to investigate the influence of posture changes on NR in patients with OSA.

Methods: Healthy controls without subjective nasal obstruction (apnea-hypopnea index (AHI) < 5 events/h), patients with OSA and subjective nasal obstruction, and patients with OSA and no subjective nasal obstruction were recruited. NR was measured by active anterior rhinomanometry in sitting, supine, left-lateral, and right-lateral postural positions. Total NR and postural change-related NR increments were calculated and compared among groups.

Results: In total, 26 healthy controls and 72 patients with OSA (mean AHI 39.7 ± 24.8 events/h) were recruited. Of patients with OSA, 38/72 (53%) had subjective nasal obstruction. Compared with controls, patients with OSA and no subjective nasal obstruction had lower total NR (inspiration, p = 0.037; expiration, p = 0.020) in the supine postural position. There was no difference in sitting, left-lateral, and right-lateral total NR among groups. Total NR was higher in lateral compared to sitting posture in both patients with OSA and in controls. The NR increment for sitting to supine postural change was significantly lower in patients with OSA (inspiration, p = 0.003; expiration, p = 0.005) compared with controls. The change in NR showed no statistically significant difference among groups in supine-left or supine-right postural change.

Conclusion: Patients with OSA had lower supine total NR and lower total NR increment in the sitting to supine postural change, which may be related to a different posture-related NR regulatory mechanism. This study provides a new exploratory direction for the compensatory mechanism of the upper airway to collapse during sleep.