Department of Mechanical Engineering, University of Maryland, College Park, MD, USA.
School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
Sci Rep. 2016 Dec 15;6:39273. doi: 10.1038/srep39273.
Pulse transit time (PTT) is being widely pursued for cuff-less blood pressure (BP) monitoring. Most efforts have employed the time delay between ECG and finger photoplethysmography (PPG) waveforms as a convenient surrogate of PTT. However, these conventional pulse arrival time (PAT) measurements include the pre-ejection period (PEP) and the time delay through small, muscular arteries and may thus be an unreliable marker of BP. We assessed a bathroom weighing scale-like system for convenient measurement of ballistocardiography and foot PPG waveforms - and thus PTT through larger, more elastic arteries - in terms of its ability to improve tracking of BP in individual subjects. We measured "scale PTT", conventional PAT, and cuff BP in humans during interventions that increased BP but changed PEP and smooth muscle contraction differently. Scale PTT tracked the diastolic BP changes well, with correlation coefficient of -0.80 ± 0.02 (mean ± SE) and root-mean-squared-error of 7.6 ± 0.5 mmHg after a best-case calibration. Conventional PAT was significantly inferior in tracking these changes, with correlation coefficient of -0.60 ± 0.04 and root-mean-squared-error of 14.6 ± 1.5 mmHg (p < 0.05). Scale PTT also tracked the systolic BP changes better than conventional PAT but not to an acceptable level. With further development, scale PTT may permit reliable, convenient measurement of BP.
脉搏传输时间（PTT）正被广泛应用于无袖带血压（BP）监测。大多数研究都采用心电图（ECG）和手指光容积脉搏波（PPG）之间的时间延迟作为 PTT 的替代指标。然而，这些传统的脉搏到达时间（PAT）测量值包括射血前期（PEP）和通过小而肌肉发达的动脉的时间延迟，因此可能不是 BP 的可靠标志物。我们评估了一种类似于浴室体重秤的系统，用于方便地测量心动描记和足部 PPG 波形，以及通过更大、更有弹性的动脉测量 PTT，以评估其在个体受试者中跟踪 BP 的能力。我们在干预期间测量了“秤 PTT”、传统 PAT 和袖带 BP，这些干预措施会升高血压，但改变 PEP 和平滑肌收缩的方式不同。在最佳校准后，秤 PTT 对舒张压变化的跟踪效果很好，相关系数为-0.80±0.02（平均值±标准误差），均方根误差为 7.6±0.5mmHg。传统 PAT 在跟踪这些变化方面明显较差，相关系数为-0.60±0.04，均方根误差为 14.6±1.5mmHg（p<0.05）。秤 PTT 对收缩压变化的跟踪也优于传统 PAT，但仍未达到可接受的水平。随着进一步的发展，秤 PTT 可能允许可靠、方便地测量 BP。
