Mouth-opening increases upper-airway collapsibility without changing resistance during midazolam sedation

T. Ayuse, T. Inazawa, S. Kurata, I. Okayasu, E. Sakamoto, K. Oi, H. Schneider, A. R. Schwartz

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Sedative doses of anesthetic agents affect upper-airway function. Oral-maxillofacial surgery is frequently performed on sedated patients whose mouths must be as open as possible if the procedures are to be accomplished successfully. We examined upper-airway pressure-flow relationships in closed mouths, mouths opened moderately, and mouths opened maximally to test the hypothesis that mouth-opening compromises upper-airway patency during midazolam sedation. From these relationships, upper-airway critical pressure (Pcrit) and upstream resistance (Rua) were derived. Maximal mouth-opening increased Pcrit to -3.6 ± 2.9 cm H2O compared with -8.7 ± 2.8 (p = 0.002) for closed mouths and -7.2 ± 4.1 (p = 0.038) for mouths opened moderately. In contrast, Rua was similar in all three conditions (18.4 ± 6.6 vs. 17.7 ± 7.6 vs. 21.5 ± 11.6 cm H2O/L/sec). Moreover, maximum mouth-opening produced an inspiratory airflow limitation at atmosphere that was eliminated when nasal pressure was adjusted to 4.3 ± 2.7 cm H2O. We conclude that maximal mouth-opening increases upper-airway collapsibility, which contributes to upper-airway obstruction at atmosphere during midazolam sedation.

Original languageEnglish (US)
Pages (from-to)718-722
Number of pages5
JournalJournal of Dental Research
Issue number9
StatePublished - Sep 2004
Externally publishedYes


  • Conscious sedation
  • Critical pressure
  • Mandibular position
  • Mouth opening
  • Sleep apnea
  • Upper airway

ASJC Scopus subject areas

  • Dentistry(all)


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