title: Predictors of nocturnal oxygen desaturation in pulmonary arterial hypertension.
abstract: BACKGROUND
  Sleep may be associated with significant respiratory compromise in patients with lung disease and can result in hypoxia. In patients with pulmonary arterial hypertension (PAH), nocturnal desaturation may not be reflected in daytime evaluations of oxygenation and can lead to worsening pulmonary hemodynamics. The study was conducted to determine the prevalence and significance of nocturnal oxygen desaturation in patients with PAH.
  
  
  METHODS
  A cross-sectional study conducted at the Cleveland Clinic. Patients were followed up at our institution except for the overnight oximetry study done at home. Data regarding degree of nocturnal desaturation, demographics, hemodynamics, pulmonary function, and functional capacity were collected.
  
  
  RESULTS
  Forty-three patients (mean age, 47.9 +/- 13.5 years [+/- SD]; 36 women and 7 men) underwent nocturnal oximetry. The etiology of PAH included idiopathic PAH (88%) and PAH associated with connective tissue diseases (12%). The majority of patients were New York Heart Association functional class II (42%) or III (53%). Thirty patients (69.7%) spent > 10% of sleep time with oxygen saturation by pulse oximetry < 90%. Desaturators were older (p = 0.024) and had higher hemoglobin (p = 0.002). Sixteen of 27 patients (59%) without desaturation < 90% during a 6-min walk test were nocturnal desaturators. Nocturnal desaturators had higher brain natriuretic protein (p = 0.004), lower cardiac index (p = 0.03), and higher mean right atrial pressure (p = 0.09), mean pulmonary artery pressure, and pulmonary vascular resistance. On echocardiography, desaturators were more likely to have moderate or severe right ventricular dilation (p = 0.04) and pericardial effusion. Only one patient had significant sleep apnea.
  
  
  CONCLUSIONS
  Nocturnal hypoxemia is common in PAH patients and correlates with advanced pulmonary hypertension and right ventricular dysfunction. Approximately 60% patients without exertional hypoxia had nocturnal desaturation. Overnight oximetry should be considered in the routine workup of PAH patients who do not demonstrate exertional desaturation.
authors.affiliation: Department of Pulmonary, Allergy, and Critical Care, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195, USA. minaio@ccf.org
authors.forename: Omar A
authors.initials: OA
authors.lastname: Minai
authors.forename: Chirag M
authors.initials: CM
authors.lastname: Pandya
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Golish
authors.forename: Jaime F
authors.initials: JF
authors.lastname: Avecillas
authors.forename: Kevin
authors.initials: K
authors.lastname: McCarthy
authors.forename: Scott
authors.initials: S
authors.lastname: Marlow
authors.forename: Alejandro C
authors.initials: AC
authors.lastname: Arroliga
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood* / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D017286:Polysomnography; D012372:ROC Curve; D012129:Respiratory Function Tests; D012890:Sleep / Q000502:physiology*
chemical_list: D010100:Oxygen