Sleep apnea-hypopnea quantification by cardiovascular data analysis
  Sleep apnea is the most common sleep disturbance and it is an important risk factor for cardiovascular disorders. Its detection relies on a polysomnography, a combination of diverse exams.   In order to detect changes due to sleep disturbances such as sleep apnea occurrences, without the need of combined recordings, we mainly analyze systolic blood pressure signals (maximal blood pressure value of each beat to beat interval). Nonstationarities in the data are uncovered by a segmentation procedure, which provides local quantities that are correlated to apnea-hypopnea events. Those quantities are the average length and average variance of stationary patches. By comparing them to an apnea score previously obtained by polysomnographic exams, we propose an apnea quantifier based on blood pressure signal.   This furnishes an alternative procedure for the detection of apnea based on a single time series, with an accuracy of 82%. 
Sabrina Camargo, Maik Riedl, Celia Anteneodo, Juergen Kurths, Thomas   Penzel, and Niels Wessel
physics.med-ph