Nasal Patency in Sitting, Supine, and Prone Positions in Individuals with and without Allergic Rhinitis

Abstract

(1) Background: Physiological changes in nasal patency in response to posture contribute to sleep-related problems. Previously, we reported that the supine and prone positions cause a significant decrease in nasal patency in subjective and objective assessments of healthy individuals. Therefore, we conducted a study to evaluate the effect of posture on nasal patency in patients with allergic rhinitis (AR); (2) Methods: The present study comprised 30 patients diagnosed with AR and 30 healthy subjects without nasal disease (non-AR). Changes in nasal patency were evaluated in the sitting, supine, and prone positions. We used the visual analog scale to evaluate subjective nasal blockage. Acoustic rhinometry and endoscopy were used to objectively measure changes in nasal patency; (3) Results: In the non-AR group, the prone position had a significant effect on subjective nasal blockage compared with the sitting position, with significant decreases in the minimal cross-sectional area (mCSA) measured by acoustic rhinometry. Furthermore, endoscopy demonstrated a significantly increased inferior turbinate hypertrophy in the non-AR group. In the AR group, there was no statistical difference in subjective nasal blockage symptoms between the different positions. However, in objective examinations (acoustic rhinometry and endoscopy), the prone position showed significantly decreased nasal patency; (4) Conclusions: In patients with AR, subjective nasal blockage did not significantly increase in the supine or prone position. Endoscopy demonstrated increased inferior turbinate hypertrophy in supine and prone positions resulting in a significant reduction in nasal cavity mCSA, indicating an objective reduction in nasal patency.

Keywords: allergic rhinitis; nasal patency; position.

Figure 1

Flowchart of the postural examinations. Questionnaires, acoustic rhinometry, and endoscopy were performed with subjects in the sitting position (1). The subjects then changed to the supine position for 15 min (2a) and underwent the same subjective and objective examinations (2b). The subjects then changed to the prone position for the above three examinations (3a,3b).

Figure 2

Measurement of nasal patency. (A) 1.7 cm mark behind the front end of a rigid endoscope. (B) The endoscope was inserted into the nasal cavity at a fixed depth to capture images. (C) The thickest part of the head of the inferior turbinate was used as the reference point with a horizontal line drawn. The width of the nasal cavity was set as “a”, the width of the inferior turbinate was set as “b”, and the degree of hypertrophy of the inferior turbinate was calculated by dividing “b” by “a” × 100 and presented as a percentage.

Figure 3

Visual analog scale. In healthy subjects without nasal disease (non-allergic rhinitis (AR) group) (A) and in patients with AR (B), the subjective assessment of nasal blockage in the sitting, supine, and prone positions was conducted using the visual analog scale with scores ranging from 0 to 100 points. * p < 0.05; *** p < 0.0001.

Figure 4

Acoustic rhinometry. Healthy subjects without nasal disease (non-allergic rhinitis (AR) group) (A) and patients with AR (B) underwent acoustic rhinometry to objectively evaluate nasal cavity patency in the sitting, supine, and prone positions. The results are presented as minimal cross-sectional area (cm²). * p < 0.05; ** p < 0.01; *** p < 0.0001.

Figure 5

Endoscopic assessment. Healthy subjects without nasal disease (non-allergic rhinitis (AR) group) and patients with AR underwent video-endoscopy on both sides of the nasal cavity in the sitting, supine, and prone positions. The results are expressed as a percentage calculated by dividing the width of the inferior turbinate by that of the nasal cavity. * p < 0.05; ** p < 0.01; *** p < 0.0001.