Fig. 5
Cyclic variation of heart rate (CVHR) detected by the autocorrelated wave detection with adaptive threshold (ACAT) algorithm during a polysomnographic examination in a representative subject with obstructive sleep apnea (OSA). Panel B is a closer view of the data in the open box in panel A. Vertical bars in panel A and arrows in panel B indicate the temporal positions of detected CVHR. The ACAT algorithm detected the nadirs of cyclic dips in interbeat intervals that accompany apnea–hypopnea events. RRI, R–R interval of ECG; SpO2, pulse oximetric arterial blood oxygen saturation; Resp, respiration by oronasal airflow. Modified Fig. 1 of reference [68]