title: Oxygen saturation regularity analysis in the diagnosis of obstructive sleep apnea.
abstract: OBJECTIVE
  The present study assessed the validity of approximate entropy (ApEn) analysis of arterial oxygen saturation (SaO(2)) data obtained from pulse oximetric recordings as a diagnostic test for obstructive sleep apnea (OSA) in patients clinically suspected of suffering this disease.
  
  
  METHODS
  A sample of 187 referred outpatients, clinically suspected of having OSA, was studied using nocturnal pulse oximetric recording performed simultaneously with complete polysomnography. ApEn analysis was applied to SaO(2) data.
  
  
  RESULTS
  Patients with OSA presented significantly higher approximate entropy levels than those without OSA (1.08+/-0.30 versus 0.47+/-0.26). Apnea-hypopnea index was correlated significantly with ApEn (r=0.607; p<0.001). Using receiver operating characteristic curve analysis, we obtained a diagnostic sensitivity of 88.3% and specificity of 82.9%, positive predictive value of 88.3% and a negative predictive value of 82.9%, at a threshold of 0.679. As a diagnostic test, this method presents high sensitivity and specificity compared to traditional methods in the diagnosis of OSA.
  
  
  CONCLUSIONS
  We conclude that ApEn analysis of SaO(2) data obtained from pulse oximetric recordings could be useful as a diagnostic technique for OSA subjects.
authors.affiliation: Hospital del Río Hortega, Servicio de Neumología, C/Cardenal Torquemada s/n, 47010 Valladolid, Spain. fsas@telefonica.net
authors.forename: Félix
authors.initials: F
authors.lastname: del Campo
authors.forename: Roberto
authors.initials: R
authors.lastname: Hornero
authors.forename: Carlos
authors.initials: C
authors.lastname: Zamarrón
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Abasolo
authors.forename: Daniel
authors.initials: D
authors.lastname: Alvarez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001185:Artificial Intelligence; D001785:Blood Gas Monitoring, Transcutaneous / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D017286:Polysomnography; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000150:complications / Q000175:diagnosis; D012372:ROC Curve; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications / Q000175:diagnosis*
chemical_list: D010100:Oxygen