Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA.
Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA.
Sci Transl Med. 2018 Mar 7;10(431). doi: 10.1126/scitranslmed.aap8674.
High blood pressure (BP) is a major cardiovascular risk factor that is treatable, yet hypertension awareness and control rates are low. Ubiquitous BP monitoring technology could improve hypertension management, but existing devices require an inflatable cuff and are not compatible with such anytime, anywhere measurement of BP. We extended the oscillometric principle, which is used by most automatic cuff devices, to develop a cuff-less BP monitoring device using a smartphone. As the user presses her/his finger against the smartphone, the external pressure of the underlying artery is steadily increased while the phone measures the applied pressure and resulting variable-amplitude blood volume oscillations. A smartphone application provides visual feedback to guide the amount of pressure applied over time via the finger pressing and computes systolic and diastolic BP from the measurements. We prospectively tested the smartphone-based device for real-time BP monitoring in human subjects to evaluate usability ( = 30) and accuracy against a standard automatic cuff-based device ( = 32). We likewise tested a finger cuff device, which uses the volume-clamp method of BP detection. About 90% of the users learned the finger actuation required by the smartphone-based device after one or two practice trials. The device yielded bias and precision errors of 3.3 and 8.8 mmHg for systolic BP and -5.6 and 7.7 mmHg for diastolic BP over a 40 to 50 mmHg range of BP. These errors were comparable to the finger cuff device. Cuff-less and calibration-free monitoring of systolic and diastolic BP may be feasible via a smartphone.
高血压（BP）是一种主要的心血管风险因素，可以治疗，但高血压的知晓率和控制率都很低。无处不在的血压监测技术可以改善高血压管理，但现有的设备需要一个可充气的袖带，并且不能随时随地进行血压测量。我们扩展了示波法原理，该原理被大多数自动袖带设备使用，开发了一种使用智能手机的无袖带血压监测设备。当用户将手指压在智能手机上时，下方动脉的外部压力会逐渐增加，而手机会测量施加的压力和随之产生的可变幅度的血流体积振动。智能手机应用程序提供视觉反馈，通过手指按压随时间推移引导施加的压力量，并根据测量结果计算收缩压和舒张压。我们前瞻性地测试了基于智能手机的设备，以实时监测人体血压，评估其可用性（=30）和准确性，与标准的自动袖带设备（=32）进行比较。我们同样测试了一种使用血压检测的容积钳夹法的手指袖带设备。大约 90%的用户在一到两次练习后学会了基于智能手机的设备所需的手指操作。该设备在 40 到 50 毫米汞柱的血压范围内，收缩压的偏差和精度误差分别为 3.3 和 8.8 毫米汞柱，舒张压的偏差和精度误差分别为-5.6 和 7.7 毫米汞柱。这些误差与手指袖带设备相当。通过智能手机可能可以实现无袖带和无需校准的收缩压和舒张压监测。
