title: Evaluation of oxidative stress markers in obstructive sleep apnea syndrome and additional antioxidant therapy: a review article.
abstract: OBJECTIVE
  The hypoxia and reoxygenation cycles in obstructive sleep apnea syndrome (OSAS) cause a change in the oxidative balance, leading to the formation of reactive oxygen species capable of reacting with other organic molecules impairing their functions. This study aimed to determine the best markers of oxidative stress in OSAS and what better antioxidant agent to be used to treat the disease.
  
  
  METHODS
  Searches were conducted in three different databases (PubMed, LILACS, SCIELO), using as descriptors the terms obstructive sleep apnea, oxidative stress, and antioxidant therapy. A total of 120 articles were found but only those considered of interest to the research were selected. Thus, 10 articles were included for further analysis regarding the biomarkers of oxidative stress in OSAS, and 6 articles to evaluate the antioxidant most often used for demonstration of efficacy.
  
  
  RESULTS
  The thioredoxin, malondialdehyde, superoxide dysmutase, and reduced iron were the most commonly used biomarkers and showed a more consistent relationship between increased oxidative stress and OSAS. As antioxidant therapy, vitamin C and N-acetylcysteine (NAC) presented interesting results as a reduction of oxidative stress, which may become an alternative to the complementary treatment of OSAS.
  
  
  CONCLUSIONS
  This review's findings agree mostly to measure that the markers of oxidative stress in OSAS may be a contributing aspect to assessment and monitoring of patient, and the antioxidant therapy appears to be beneficial in the treatment of OSAS.
authors.affiliation: Medical Sleep and ENT of Santa Casa Hospital, Professora Hígia Vasconcelos street, 193, Ponta verde, Maceió, Alagoas, 57035-140, Brazil. ablira@hotmail.com.
authors.forename: Amanda Bastos
authors.initials: AB
authors.lastname: Lira
authors.affiliation: University of Alagoas/Brazil, Maceió, Alagoas, Brazil.
authors.forename: Célio Fernando
authors.initials: CF
authors.lastname: de Sousa Rodrigues
mesh_terms: D000111:Acetylcysteine / Q000627:therapeutic use; D000328:Adult; D000975:Antioxidants / Q000627:therapeutic use*; D001205:Ascorbic Acid / Q000627:therapeutic use; D015415:Biomarkers / Q000097:blood*; D045422:Continuous Positive Airway Pressure; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000097:blood*; D020181:Sleep Apnea, Obstructive / Q000188:drug therapy* / Q000503:physiopathology*
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D017382:Reactive Oxygen Species; D001205:Ascorbic Acid; D000111:Acetylcysteine
keywords: Antioxidant therapy; Markers; Obstructive sleep apnea; Oxidative stress