This paper presents multi-scale fractal dimension (MFD) for the complexity assessment of heart rate variability (HRV) and systolic blood pressure variability (SBPV) under postural stress. A comparison of MFD with multi-scale approximate entropy (MAE) at multiple time scales ([Formula: see text]–10) is presented. The simulations were conducted on 50 random noise (RN), fractional Brownian motion (fBm), and MIX(p) [ 1 ] series along with standard EuroBaVar dataset. Also, 50 healthy volunteers, 20 post-acute myocardial infarction (AMI) patients participated in the study. It is observed that MFD and MAE decrease with [Formula: see text] for healthy volunteers and remained constant for post AMI and BRS failure patients. Average MFD of HRV in supine position is always significantly different than standing position scale except [Formula: see text], whereas the average MAE of HRV shows no significant difference ([Formula: see text]) between supine and standing postures at each [Formula: see text] except [Formula: see text] for healthy volunteers. Average MFD of HRV in supine position is significantly different than the standing position for [Formula: see text]–7, whereas the average MAE of HRV shows significant difference ([Formula: see text]) between supine and standing postures at [Formula: see text] for post AMI, and patients with impaired baroreflex sensitivity (BRS). Average MFD of SBPV in position is significantly different ([Formula: see text]) than standing position at each [Formula: see text], whereas the average MAE of SBPV shows no significant difference ([Formula: see text]) between supine and standing postures at each [Formula: see text] except [Formula: see text]. The complexity of HRV in standing position is less than that of supine position as shown by lower MFD and MAE values in standing than that of supine position, however, the complexity of SBPV decreases from standing to supine position indicating prevalence of sympathetic control.

中文翻译：

---

量化心率变异性和收缩压变异性的多尺度分形维数：姿势应力分析

本文提出了多尺度分形维数 (MFD)，用于在姿势压力下对心率变异性 (HRV) 和收缩压变异性 (SBPV) 进行复杂性评估。给出了 MFD 与多尺度近似熵 (MAE) 在多个时间尺度上的比较（[公式：见文本]–10）。模拟是在 50 个随机噪声 (RN)、分数布朗运动 (fBm) 和 MIX(p) [1] 系列以及标准 EuroBaVar 数据集上进行的。此外，50 名健康志愿者、20 名急性心肌梗死 (AMI) 患者参与了该研究。观察到，对于健康志愿者，MFD 和 MAE 随着 [公式：见正文] 降低，而对于 AMI 和 BRS 失败患者，则保持不变。仰卧位 HRV 的平均 MFD 总是与站立位量表显着不同，除了 [公式：见文本]，而HRV的平均MAE在每个[公式：见文本]的仰卧和站立姿势之间没有显着差异（[公式：见文本]），除了健康志愿者的[公式：见文本]。仰卧位 HRV 的平均 MFD 与站立位 [公式：见文本]–7 显着不同，而 HRV 的平均 MAE 在 [公式： AMI 后和压力反射敏感性受损 (BRS) 的患者见正文]。SBPV 的平均 MFD 在每个 [公式：见文本] 与站立位置显着不同（[公式：见文本]），而 SBPV 的平均 MAE 在仰卧和仰卧位之间没有显着差异（[公式：见文本]）除了[公式：见文本]之外，每个[公式：见文本]的站立姿势。