title: Airway and alveolar nitric oxide measurements in obstructive sleep apnea syndrome.
abstract: OBJECTIVE
  The process of intermittent hypoxia-reoxygenation produces airway inflammation and endothelial dysfunction that favors the development of cardiovascular disorders in obstructive sleep apnea syndrome (OSAS). Nitric oxide (NO) is an important mediator in airway inflammation and the regulation of endothelium-dependent vasodilation.
  
  
  METHODS
  This study compared airway NO (FE(NO)) and alveolar NO (CA(NO)) measurements in exhaled breath in 30 OSAS patients to those of 30 healthy (non-OSAS) individuals and determined the relationship between NO levels and OSAS severity. Additionally, NO measurements were analyzed after 3 months of CPAP treatment.
  
  
  RESULTS
  The mean (±SD) FE(NO) level in the OSAS group (27.2 ± 18 ppb) was higher than in the healthy non-OSAS group (p = 0.006). The mean CA(NO) level was 1.65 ± 0.90 ppb, lower than in the non-OSAS group (p = 0.001). A significant correlation was found between FE(NO) and CA(NO) levels and the apnea-hypopnea index (AHI) in the OSAS group (r = 0.8, p < 0.05; r = -0.9, p = 0.01, respectively). FE(NO) levels decreased and CA(NO) levels increased significantly after CPAP treatment.
  
  
  CONCLUSIONS
  Severe OSAS patients have higher FE(NO) and lower CA(NO) levels and these are restored to normal after CPAP treatment, reflecting the correction of local upper airway inflammation and endothelial dysfunction present in OSAS patients. Exhaled breath techniques can be useful to identify airway inflammation and endothelial dysfunction in severe OSAS patients.
authors.affiliation: Sleep Laboratory, Respiratory Medicine Department, Hospital de la Santa Creu i Sant Pau, Mas Casanovas, 90, Barcelona 08025, Spain. afortuna@santpau.cat
authors.forename: A M
authors.initials: AM
authors.lastname: Fortuna
authors.forename: R
authors.initials: R
authors.lastname: Miralda
authors.forename: N
authors.initials: N
authors.lastname: Calaf
authors.forename: M
authors.initials: M
authors.lastname: González
authors.forename: P
authors.initials: P
authors.lastname: Casan
authors.forename: M
authors.initials: M
authors.lastname: Mayos
mesh_terms: D002318:Cardiovascular Diseases / Q000517:prevention & control; D045422:Continuous Positive Airway Pressure; D004730:Endothelium, Vascular / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D007249:Inflammation / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000378:metabolism*; D020181:Sleep Apnea, Obstructive / Q000378:metabolism* / Q000503:physiopathology / Q000628:therapy
chemical_list: D009569:Nitric Oxide