title: Cross approximate entropy analysis of nocturnal oximetry signals in the diagnosis of the obstructive sleep apnea syndrome.
abstract: This study is focused on the analysis of blood oxygen saturation (SaO(2)) and heart rate (HR) from nocturnal oximetry using cross approximate entropy (Cross-ApEn). We assessed its usefulness in screening obstructive sleep apnea (OSA) syndrome. We applied Cross-ApEn(m,r,N) to quantify the asynchrony between paired SaO(2) and HR records of 74 patients (44 with a positive OSA diagnosis and 30 with a negative OSA diagnosis). Cross-ApEn values were significantly lower in the OSA positive group compared with those obtained in the OSA negative group. A receiver operating characteristic (ROC) analysis showed that the best results, in terms of diagnostic accuracy, were achieved with m = 2 and r = 0.6. With these input parameters, the optimum decision threshold was found at 1.7, where we achieved 95.5% sensitivity, 73.3% specificity and 86.5% accuracy. Further analyses should be carried out with new and larger data sets to test the usefulness of our methodology prospectively.
authors.affiliation: E.T.S. Ingenieros de Telecommun., Valladolid Univ., Valladolid, Spain. dalvgon@ribera.tel.uva.es
authors.forename: Daniel
authors.initials: D
authors.lastname: Alvarez
authors.forename: Roberto
authors.initials: R
authors.lastname: Hornero
authors.forename: Mariá
authors.initials: M
authors.lastname: Garcia
authors.forename: Felix
authors.initials: F
authors.lastname: del Campo
authors.forename: Carlos
authors.initials: C
authors.lastname: Zamarron
authors.forename: Miguel
authors.initials: M
authors.lastname: López
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D019277:Entropy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010092:Oximetry / Q000295:instrumentation* / Q000379:methods; D010363:Pattern Recognition, Automated; D017286:Polysomnography / Q000295:instrumentation* / Q000379:methods; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*