title: Evaluating nocturnal oxygen desaturation in COPD--revised.
abstract: BACKGROUND
  Although in patients with COPD, the approach to daytime hypoxemia using long-term oxygen therapy (LTOT) is established, the best approach to transient nocturnal desaturation varies among clinicians. An understanding of the prevalence of nocturnal desaturation in COPD, in the absence of other respiratory co-morbidities, is an important step towards its standardized management.
  
  
  METHODS
  We conducted a 5 site cross-sectional study of stable patients with COPD and mild-to-moderate daytime hypoxemia (PaO(2) 56-69 mmHg). Nocturnal saturation was monitored using home oximetry on 2 occasions over a 2-week period. Patients were classified in 3 categories: (A) no significant nocturnal desaturation; (B) significant nocturnal desaturation without evidence of sleep apnea; (C) significant nocturnal desaturation with evidence of sleep apnea.
  
  
  RESULTS
  In 128 patients (mean FEV(1): 37% predicted), we noted an excellent test-retest reliability between the 2 oximetries. Forty-nine patients (38%) were classified as nocturnal desaturators without evidence of sleep apnea, and 20 patients (16%) were classified as desaturators with evidence of sleep apnea. Nocturnal desaturation without sleep apnea could not be predicted by any patient characteristic or physiological measure.
  
  
  CONCLUSIONS
  A significant proportion (38%) of patients with moderate-to-severe COPD who do not qualify for home oxygen therapy based on their daytime PaO(2) have nocturnal oxygen desaturation without evidence of sleep apnea. Home oximetry is an effective practical method for screening this population.
authors.affiliation: Centre de recherche, Institut universitaire de cardiologie et de pneumologie de Québec, 2725 Chemin Ste-Foy, Québec, Québec G1V 4G5, Canada. Yves.Lacasse@med.ulaval.ca
authors.forename: Yves
authors.initials: Y
authors.lastname: Lacasse
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sériès
authors.forename: Nada
authors.initials: N
authors.lastname: Vujovic-Zotovic
authors.forename: Roger
authors.initials: R
authors.lastname: Goldstein
authors.forename: Jean
authors.initials: J
authors.lastname: Bourbeau
authors.forename: Richard
authors.initials: R
authors.lastname: Lecours
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Aaron
authors.forename: François
authors.initials: F
authors.lastname: Maltais
mesh_terms: D000368:Aged; D002170:Canada; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D010092:Oximetry / Q000379:methods*; D010102:Oxygen Inhalation Therapy / Q000379:methods* / Q000592:standards; D010865:Pilot Projects; D017286:Polysomnography; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012891:Sleep Apnea Syndromes / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*