Defining phenotypic causes of obstructive sleep apnea. Identification of novel therapeutic targets

Am J Respir Crit Care Med. 2013 Oct 15;188(8):996-1004. doi: 10.1164/rccm.201303-0448OC.


Rationale: The pathophysiologic causes of obstructive sleep apnea (OSA) likely vary among patients but have not been well characterized.

Objectives: To define carefully the proportion of key anatomic and nonanatomic contributions in a relatively large cohort of patients with OSA and control subjects to identify pathophysiologic targets for future novel therapies for OSA.

Methods: Seventy-five men and women with and without OSA aged 20-65 years were studied on three separate nights. Initially, the apnea-hypopnea index was determined by polysomnography followed by determination of anatomic (passive critical closing pressure of the upper airway [Pcrit]) and nonanatomic (genioglossus muscle responsiveness, arousal threshold, and respiratory control stability; loop gain) contributions to OSA.

Measurements and main results: Pathophysiologic traits varied substantially among participants. A total of 36% of patients with OSA had minimal genioglossus muscle responsiveness during sleep, 37% had a low arousal threshold, and 36% had high loop gain. A total of 28% had multiple nonanatomic features. Although overall the upper airway was more collapsible in patients with OSA (Pcrit, 0.3 [-1.5 to 1.9] vs. -6.2 [-12.4 to -3.6] cm H2O; P <0.01), 19% had a relatively noncollapsible upper airway similar to many of the control subjects (Pcrit, -2 to -5 cm H2O). In these patients, loop gain was almost twice as high as patients with a Pcrit greater than -2 cm H2O (-5.9 [-8.8 to -4.5] vs. -3.2 [-4.8 to -2.4] dimensionless; P = 0.01). A three-point scale for weighting the relative contribution of the traits is proposed. It suggests that nonanatomic features play an important role in 56% of patients with OSA.

Conclusions: This study confirms that OSA is a heterogeneous disorder. Although Pcrit-anatomy is an important determinant, abnormalities in nonanatomic traits are also present in most patients with OSA.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Case-Control Studies
  • Female
  • Humans
  • Male
  • Middle Aged
  • Phenotype
  • Polysomnography
  • Respiratory Muscles / pathology
  • Respiratory Muscles / physiopathology
  • Respiratory System / anatomy & histology
  • Respiratory System / pathology
  • Respiratory System / physiopathology
  • Sleep Apnea, Obstructive / etiology*
  • Sleep Apnea, Obstructive / pathology
  • Sleep Apnea, Obstructive / physiopathology
  • Sleep Apnea, Obstructive / therapy
  • Young Adult