Heart Rate Variability from Wearable Photoplethysmography Systems: Implications in Sleep Studies at High Altitude (dataset)

public anonymized dataset of the main findings of the study Abstract: The interest in photoplethysmography (PPG) for sleep monitoring is increasing because PPG may allow assessing the heart rate variability (HRV), which is particularly important in breathing disorders. Thus, we aim to evaluate how PPG wearable systems measure HRV during sleep at high altitudes, where hypobaric hypoxia induces respiratory disturbances. We considered PPG and electrocardiographic recordings in 21 volunteers sleeping at 4554m asl (as a model of sleep breathing disorder), and 5 alpine guides sleeping at sea level, 6000m and 6800m asl. Power spectra, multiscale entropy, and self-similarity were calculated for PPG tachograms and electrocardiography R-R intervals (RRI). Results demonstrated that wearable PPG devices provide HRV measures even at extremely high altitudes. However, the comparison between PPG tachograms and RRI showed discrepancies in the faster spectral components and at the shorter scales of self-similarity and entropy (TABLE 1). Furthermore, the changes in sleep HRV from sea level to extremely high altitudes quantified by RRI and PPG tachograms in the 5 alpine guides tended to be different at the faster frequencies and shorter scales (TABLE 2). Discrepancies may be explained by modulations of pulse wave velocity and should be considered to interpret correctly autonomic alterations during sleep from HRV analysis.本数据集为经匿名化处理的研究核心发现公开数据集。 摘要：光电容积描记法（photoplethysmography, PPG）用于睡眠监测的关注度日益提升，因其可实现心率变异性（heart rate variability, HRV）的评估，而心率变异性在呼吸障碍相关研究中尤为关键。本研究旨在评估穿戴式PPG设备在高海拔环境下的睡眠HRV测量性能——高海拔低氧低压环境可诱发呼吸功能紊乱。本次研究共纳入21名在海拔4554米处睡眠的志愿者（作为睡眠呼吸障碍模型），另招募5名分别在海平面、海拔6000米与6800米处睡眠的高山向导，对所有受试者同步采集PPG与心电图（electrocardiographic, ECG）信号。研究分别针对PPG心动图与心电图R-R间期（R-R interval, RRI）计算了功率谱、多尺度熵与自相似性指标。研究结果表明，即便在极端高海拔环境下，穿戴式PPG设备仍可有效获取HRV相关测量指标。然而，对比PPG心动图与RRI数据可见，二者在快速频谱成分以及自相似性与熵的短尺度区间存在显著差异（见表1）。此外，针对5名高山向导的分析显示，经RRI与PPG心动图量化的、从海平面到极端高海拔环境下的睡眠HRV变化，在快速频率与短尺度区间呈现出不一致的趋势（见表2）。上述差异可通过脉搏波速度的调制作用加以解释，在基于HRV分析解读睡眠期间自主神经功能改变时，需充分考虑该因素以确保结果解读的准确性。