title: Obstructive sleep apnea and oxygen therapy: a systematic review of the literature and meta-analysis.
abstract: BACKGROUND
  Hypoxemia is an immediate consequence of obstructive sleep apnea. Oxygen (O2) administration has been used as an alternative treatment in patients with obstructive sleep apnea (OSA) who do not adhere to continuous positive airway pressure (CPAP) in order to reduce the deleterious effects of intermittent hypoxemia during sleep. This systematic review aims to investigate the effects of O2 therapy on patients with OSA.
  
  
  METHODS
  We conducted a systematic search of the databases Medline, Embase, Cochrane Central Register of Controlled Trials (1(st) Quarter 2011), Cochrane Database of Systematic Reviews (from 1950 to February 2011). Our search strategy yielded 4,793 citations. Irrelevant papers were excluded by title and abstract review, leaving 105 manuscripts. We reviewed all prospective studies that included: (1) a target population with obstructive sleep apnea, (2) O2 therapy and/or CPAP as a study intervention, (3) the effects of O2 on the apnea-hypopnea index (AHI), nocturnal hypoxemia, or apnea duration.
  
  
  RESULTS
  We identified 14 studies including a total of 359 patients. Nine studies were of single cohort design, while 5 studies were randomized control trials with 3 groups (CPAP, oxygen, and placebo/sham CPAP). When CPAP was compared to O2 therapy, all but one showed a significant improvement in AHI. Ten studies demonstrated that O2 therapy improved oxygen saturation vs. placebo. However, the average duration of apnea and hypopnea episodes were longer in patients receiving O2 therapy than those receiving placebo.
  
  
  CONCLUSIONS
  This review shows that O2 therapy significantly improves oxygen saturation in patients with OSA. However, it may also increase the duration of apnea-hypopnea events.
authors.affiliation: Department of Anesthesiology, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: Vanita
authors.initials: V
authors.lastname: Mehta
authors.forename: Tajender S
authors.initials: TS
authors.lastname: Vasu
authors.forename: Barbara
authors.initials: B
authors.lastname: Phillips
authors.forename: Frances
authors.initials: F
authors.lastname: Chung
mesh_terms: D045422:Continuous Positive Airway Pressure; D006801:Humans; D006931:Hyperbaric Oxygenation; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D016896:Treatment Outcome
keywords: CPAP; OSA; oxygen therapy