title: Prevalence of patent foramen ovale and its contribution to hypoxemia in patients with obstructive sleep apnea.
abstract: OBJECTIVE
  The objectives of this study were (1) to assess the prevalence of patent foramen ovale (PFO) by means of contrast transesophageal echocardiography (TEE) in patients with obstructive sleep apnea, and (2) to determine the potential contribution of right to left interatrial shunting to systemic oxygen desaturation following the performance of Valsalva maneuver.
  
  
  METHODS
  Performance of contrast TEE during Valsalva maneuver with simultaneous measurement of systemic arterial oxygen saturation (SaO2) by means of pulse oximetry in patients with obstructive sleep apnea and a control group.
  
  
  METHODS
  Government teaching hospital, university hospital affiliate.
  
  
  METHODS
  Study group comprised 48 patients with documented obstructive sleep apnea and 24 control subjects.
  
  
  METHODS
  Sleep studies, contrast TEE, Valsalva maneuver, pulse oximetry.
  
  
  RESULTS
  Thirty-three of 48 patients with obstructive sleep apnea compared with 4 of 24 control patients had a detectable PFO (69% vs 17%; p < 0.0001). All sleep apnea patients had comparable baseline SaO2 regardless of the presence of a PFO (93.9+/-1.7% vs 95+/-1.2%; p=not significant). After performance of a Valsalva maneuver, however, a significantly greater fall in SaO2 was observed in patients with obstructive sleep apnea and PFO compared with patients with obstructive sleep apnea without PFO (-2.4 +/- 1.5% vs -1.3 +/- 0.6%; p=0.007). A statistically significant fall in SaO2 (defined as > 4 SD of recorded SaO2 values after Valsalva maneuver in patients without PFO) was found in one third of patients with sleep apnea and PFO.
  
  
  CONCLUSIONS
  We conclude that there is an increased prevalence of PFO in patients with obstructive sleep apnea that could contribute to significant hypoxemia after a Valsalva maneuver in approximately one third of these patients.
authors.affiliation: Section of Cardiology, Veterans Affairs Medical Center, Salem, VA 24153, USA.
authors.forename: H
authors.initials: H
authors.lastname: Shanoudy
authors.forename: A
authors.initials: A
authors.lastname: Soliman
authors.forename: P
authors.initials: P
authors.lastname: Raggi
authors.forename: J W
authors.initials: JW
authors.lastname: Liu
authors.forename: D C
authors.initials: DC
authors.lastname: Russell
authors.forename: N F
authors.initials: NF
authors.lastname: Jarmukli
mesh_terms: D000368:Aged; D017548:Echocardiography, Transesophageal; D004562:Electrocardiography; D006344:Heart Septal Defects, Atrial / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D017286:Polysomnography; D015995:Prevalence; D012129:Respiratory Function Tests; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D014636:Valsalva Maneuver