The site and function of the nasal valve

Area of Science:

• Otolaryngology
• Respiratory Physiology
• Nasal Airway Dynamics

Background:

• Previous research suggested the nasal vestibule is the primary site of airflow resistance.
• Understanding nasal resistance is crucial for managing nasal congestion and surgical outcomes.

Purpose of the Study:

• To investigate the precise location of respiratory airflow resistance in anatomically normal noses.
• To determine how nasal congestion affects airflow resistance in different nasal regions.
• To evaluate the role of alar dilator muscles in maintaining nasal patency.

Main Methods:

• Utilized a "head-out" body plethysmograph to measure nasal airflow resistance.
• Assessed resistance in untreated, congested, and decongested nasal conditions.
• Employed electromyography (EMG) to record inspiratory alar dilator muscle activity.
• Investigated nasal patency under varying ventilation conditions and with induced muscle paralysis.

Main Results:

• Approximately two-thirds of total nasal airflow resistance was located in the bony nasal cavity near the pyriform aperture, with one-third in the cartilaginous vestibule.
• Both bony and vestibular resistance changed proportionally with mucosal congestion.
• Congestion led to forward expansion of the inferior turbinates, contributing to vestibular resistance changes.
• Inspiratory alar dilator muscle activity increased with ventilation and congestion, preventing alar collapse in normal breathing.
• Alar collapse occurred during unilateral breathing or with paralysis of alar muscles.

Conclusions:

• The bony nasal cavity, specifically around the pyriform aperture, is the main site of nasal airflow resistance.
• Nasal congestion impacts resistance in both the bony and vestibular regions.
• Inferior turbinate positioning and alar muscle function are critical for maintaining nasal airway patency, especially during congestion.