How does open-mouth breathing influence upper airway anatomy?

Area of Science:

• Sleep Medicine
• Otolaryngology
• Respiratory Physiology

Background:

• Open-mouth breathing during sleep is suspected to exacerbate obstructive sleep apnea (OSA).
• Understanding the anatomical consequences of mouth breathing is crucial for managing OSA and CPAP therapy adherence.

Purpose of the Study:

• To investigate the impact of open-mouth breathing on upper airway anatomy.
• To correlate anatomical changes with OSA severity and CPAP therapy outcomes.

Main Methods:

• A cross-sectional study involving 28 subjects.
• Utilized lateral cephalometry and fiberoptic nasopharyngoscopy to assess upper airway dimensions.
• Compared anatomical measurements with the mouth open versus closed.

Main Results:

• Open-mouth breathing significantly reduced retropalatal and retroglossal distances and cross-sectional areas.
• Pharyngeal length increased, and the mandible-to-hyoid bone distance (MP-H) shortened.
• No significant changes were observed in SNA or hypopharyngeal distance.

Conclusions:

• Open-mouth breathing leads to significant anatomical alterations in the upper airway.
• These changes, including reduced airway areas and altered pharyngeal dimensions, likely contribute to increased OSA severity.
• Findings suggest a mechanism for poor adherence to nasal CPAP therapy in mouth breathers.