Association Between Breathing Route, Oxygen Desaturation, and Upper Airway Morphology

Laryngoscope. 2021 Feb;131(2):E659-E664. doi: 10.1002/lary.28774. Epub 2020 May 30.


Objectives/hypothesis: This study aimed to assess the role of capnography in objectively evaluating breathing routes during drug-induced sleep endoscopy (DISE) and further elucidate the relationship between breathing route, obstructive sleep apnea (OSA) severity, and DISE findings.

Study design: Prospective observational study.

Methods: Nighty-five patients with established OSA were recruited for this study from May 2017 to May 2019. DISE was performed in the operating room. Sedation was maintained with propofol using a target-controlled infusion system and the depth of sedation was monitored based on the bispectral index. The breathing routes, which included oral breathing, oronasal breathing, and nasal breathing, were detected using capnography. DISE findings were recorded using the VOTE (velum, oropharynx, base of tongue, and epiglottis) classification.

Results: Patients with mouth breathing were associated with increased OSA severity, worse oximetric variables, and higher body mass index in comparison with those with other breathing routes. Mouth breathing was associated with a higher degree and higher prevalence of lateral pharyngeal wall collapse and tongue base collapse during DISE.

Conclusions: Mouth breathing was significantly associated with worse oxygen desaturation and increased degree of upper airway collapse. Therefore, patients with mouth breathing during propofol-based intravenous anesthesia should be carefully monitored.

Level of evidence: 4 Laryngoscope, 131:E659-E664, 2021.

Keywords: Sleep apnea; breathing route; drug-induced sleep endoscopy; oxygen desaturation; propofol; upper airway.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Capnography* / methods
  • Female
  • Humans
  • Male
  • Middle Aged
  • Oxygen / blood
  • Polysomnography
  • Prospective Studies
  • Respiration*
  • Respiratory System / pathology*
  • Sleep Apnea, Obstructive / metabolism
  • Sleep Apnea, Obstructive / pathology
  • Sleep Apnea, Obstructive / physiopathology*


  • Oxygen