Upper airway pressure-flow relationships in obstructive sleep apnea

P. L. Smith, R. A. Wise, A. R. Gold, A. R. Schwartz, S. Permutt

Research output: Contribution to journalArticlepeer-review

309 Scopus citations


We examined the pressure-flow relationships in patients with obstructive sleep apnea utilizing the concepts of a Starling resistor. In six patients with obstructive sleep apnea, we applied incremental levels of positive pressure through a nasal mask during non-rapid-eye-movement sleep. A positive critical opening pressure (Pcrit) of 3.3±3.3 (SD) cmH2O was demonstrated. As nasal pressure was raised above Pcrit, inspiratory airflow increased in proportion to the level of positive pressure applied until apneas were abolished (P<0.01). However, at pressures greater than Pcrit, esophageal pressures either did not correlate or correlated inversely with inspiratory airflow provided that esophageal pressure was less than Pcrit. When pressure was applied to a full face mask, inspiratory airflow did not occur and Pcrit could not be obtained at pressures well above Pcrit demonstrated with the nasal mask. These results are consistent with the view that the upper airway functions as a Starling resistor with a collapsible segment in the oropharynx. These findings offer a unifying construct for the association of sleep apnea, periodic hypopnea, and snoring.

Original languageEnglish (US)
Pages (from-to)789-795
Number of pages7
JournalJournal of applied physiology
Issue number2
StatePublished - 1988

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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