Comparison of the ankle-brachial index with parameters of stiffness and peripheral arterial resistance assessed by photoplethysmography in elderly patients

Abstract Background The ankle-brachial index (ABI) uses the ratio between systolic blood pressures at the ankle and the arm to diagnose peripheral arterial disease (PAD) noninvasively. Photoplethysmography (PPG) measures and records changes to the blood volume in the human body using optical techniques. Objectives The objective of this study was to compare ABI with arterial stiffness and peripheral resistance parameters assessed using PPG in elderly patients and to propose a model for prediction of ABI. Methods A cross-sectional, quantitative study was conducted. The sample comprised elderly patients seen at a medical specialties clinic at the Universidade do Sul de Santa Catarina (UNISUL), Brazil. Age, sex, body mass index (BMI), comorbidities, smoking, and physical activity were recorded. The variables obtained using PPG and ABI were compared using bivariate and multivariate linear regression, with an α error of 0.05. Results A total of 93 elderly patients were assessed, 63.4% of whom were women. In 98.9% of cases, ABI was within normal limits. Comparison of ABI with variables acquired by PPG revealed significant associations with age. However, no significant associations were observed between ABI and PPG. The multivariate model indicated that only age, sex, and smoking were associated with ABI. Conclusions In conclusion, ABI and PPG exhibited associations with arterial aging, considering its correlation with age. However, ABI was only related to age, sex, and smoking. More studies are needed to evaluate the potential uses of PPG for screening for vascular diseases in ambulatory settings.

摘要 背景 踝臂指数（ankle-brachial index, ABI）通过测量踝部与上臂的收缩压比值，实现外周动脉疾病（peripheral arterial disease, PAD）的无创诊断。光电容积描记法（photoplethysmography, PPG）借助光学技术检测并记录人体血容量的动态变化。 研究目的 本研究旨在对比老年患者的ABI与PPG评估所得的动脉僵硬度及外周阻力参数，并构建ABI预测模型。 研究方法 本研究为横断面定量研究。研究对象为巴西圣卡塔琳娜南部大学（Universidade do Sul de Santa Catarina, UNISUL）专科门诊收治的老年患者。记录受试者的年龄、性别、体质量指数（body mass index, BMI）、合并症、吸烟史及体力活动水平。采用双变量及多元线性回归分析比较PPG与ABI获取的各项变量，检验水准α设定为0.05。 研究结果 共纳入93例老年患者，其中女性占比63.4%。98.9%的受试者ABI处于正常参考范围。将ABI与PPG获取的变量进行对比后发现，ABI仅与年龄存在显著关联，而ABI与其余PPG评估参数未观察到显著相关性。多元回归模型结果显示，仅年龄、性别及吸烟史与ABI显著相关。 研究结论 综上，考虑到动脉衰老与年龄的相关性，ABI与PPG均与动脉衰老存在关联，但ABI仅与年龄、性别及吸烟史相关。未来仍需开展更多研究，以评估PPG在门诊环境中用于血管疾病筛查的应用潜力。