title: Analysis of nocturnal oxygen saturation recordings using kernel entropy to assist in sleep apnea-hypopnea diagnosis.
abstract: In this study, a new entropy measure known as kernel entropy (KerEnt), which quantifies the irregularity in a series, was applied to nocturnal oxygen saturation (SaO(2)) recordings. A total of 96 subjects suspected of suffering from sleep apnea-hypopnea syndrome (SAHS) took part in the study: 32 SAHS-negative and 64 SAHS-positive subjects. Their SaO(2) signals were separately processed by means of KerEnt. Our results show that a higher degree of irregularity is associated to SAHS-positive subjects. Statistical analysis revealed significant differences between the KerEnt values of SAHS-negative and SAHS-positive groups. The diagnostic utility of this parameter was studied by means of receiver operating characteristic (ROC) analysis. A classification accuracy of 81.25% (81.25% sensitivity and 81.25% specificity) was achieved. Repeated apneas during sleep increase irregularity in SaO(2) data. This effect can be measured by KerEnt in order to detect SAHS. This non-linear measure can provide useful information for the development of alternative diagnostic techniques in order to reduce the demand for conventional polysomnography (PSG).
authors.affiliation: Biomedical Engineering Group, ETSI de Telecomunicación, University of Valladolid, 47011 Valladolid, Spain. jvmarcos@gmail.com
authors.forename: J Victor
authors.initials: JV
authors.lastname: Marcos
authors.forename: Roberto
authors.initials: R
authors.lastname: Hornero
authors.forename: Ian T
authors.initials: IT
authors.lastname: Nabney
authors.forename: Daniel
authors.initials: D
authors.lastname: Álvarez
authors.forename: Félix
authors.initials: F
authors.lastname: Del Campo
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D019277:Entropy; D005260:Female; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D017286:Polysomnography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012891:Sleep Apnea Syndromes / Q000097:blood* / Q000175:diagnosis*
chemical_list: D010100:Oxygen