Unobtrusive and Affordable Blood Pressure Monitoring Via Pulse Transit Time

描述（由申请人提供）：高血压是一种主要的心血管风险因素，在美国和印度的许多人中是可治疗的，但未被发现或不受控制。非侵入性和负担得起的血压（BP）监测技术可以改善高血压的检测和控制，特别是在低资源环境中。用于实现这种技术的潜在方法是脉搏传导时间（PTT）。事实上，PTT与舒张压相关，正如许多研究所证明的那样，并且可以简单地从近端和远端动脉波形之间的相对定时进行估计。但是，在方便地测量两个波形、准确地估计PTT、将PTT校准为BP以及从PTT确定收缩压方面仍然存在挑战。总体目标是克服这些挑战，从而建立通过PTT进行不引人注目的、负担得起的、高通量或个性化BP监测的技术。具体目标是：（1）开发用于近端和远端动脉波形的方便和准确的接触测量的廉价系统;（2）开发用于近端和远端动脉波形的非接触测量的低成本系统;（3）开发用于以高准确度并且在收缩期和舒张期两者估计PTT的方法;（4）开发用于将PTT准确和方便地校准到BP的系统;以及（5）针对来自人类的参考BP测量来验证所述系统和方法。将以体重秤、椅子和鞋子的形式构建基于心冲击描记器（BCG）的系统，并与光电体积描记器（PPG）传感器连接，以无缝测量近端（BCG）和远端（PPG）波形。将创建网络摄像头和监控摄像头形式的视频处理系统，以从静止和不太合作的人的面部（近端）和手部（远端）获得非接触式PPG波形。将设计动脉建模方法，以从整个波形准确估计PTT，而不是通过传统的脚到脚的时间延迟，并在收缩期和舒张期。将设计物理动脉测量建模方法并与动脉建模方法结合，以使用袖带构建准确的受试者特异性校准曲线，但不涉及操作员，并将创建回归方法以仅根据基本受试者信息（例如，年龄）。将从健康志愿者和高血压门诊患者中收集数据，听诊用于参考BP值，ICU中的一些高血压患者血压不稳定，导管到位用于金标准参考BP值。系统和方法将以各种方式进行测试，包括BP误差和高BP检测。最后，该技术将针对成本进行优化，并集成到智能手机中以便于操作。该项目的成功完成最终将有助于降低美国和印度的死亡率和发病率。

DESCRIPTION (provided by applicant): Hypertension is a major cardiovascular risk factor that is treatable, but undetected or uncontrolled, in many people in the US and India. Unobtrusive and affordable blood pressure (BP) monitoring technology could improve hypertension detection and control, especially in low resource settings. A potential approach for realizing such technology is pulse transit time (PTT). Indeed, PTT correlates with diastolic BP, as evidenced by many studies, and can be estimated simply from the relative timing between proximal and distal arterial waveforms. But, challenges remain in conveniently measuring the two waveforms, accurately estimating PTT, calibrating PTT to BP, and determining systolic BP from PTT. The overall objective is to overcome these challenges and thereby establish technologies for unobtrusive, affordable, and high throughput or individualized BP monitoring via PTT. The specific aims are: (1) to develop inexpensive systems for convenient and accurate contact measurement of proximal and distal arterial waveforms; (2) to develop low cost systems for noncontact measurement of proximal and distal arterial waveforms; (3) to develop methods for estimation of PTT with high accuracy and at both systole and diastole; (4) to develop systems for accurate and convenient calibration of PTT to BP; and (5) to validate the systems and methods against reference BP measurements from humans. Ballistocardiograph (BCG)-based systems in the form of a weighing scale, chair, and shoe will be built and interfaced with photoplethysmograph (PPG) sensors for seamless measurement of the proximal (BCG) and distal (PPG) waveforms. Video processing systems in the form of a webcam and surveillance camera will be created to obtain non-contact PPG waveforms from the face (proximal) and hand (distal) of still and less cooperative people. Arterial modeling methods will be devised to estimate PTT accurately from the entire waveforms, rather than via the conventional foot-to-foot time delay, and at both systole and diastole. Physical oscillometric modeling methods will be designed and combined with arterial modeling methods to construct an accurate, subject-specific calibration curve using a cuff but without involving an operator, and regression methods will be created to form the calibration curve without using a cuff from only basic subject information (e.g., age). Data will be collected from healthy volunteers and hypertensive outpatients with auscultation used for reference BP values and some hypertensive patients in the ICU with unstable BP and catheters in place for gold standard reference BP values. The systems and methods will be tested in various ways including BP error and high BP detection. Finally, the technology will be optimized for cost and integrated to smartphones for ease of operation. Successful completion of this project could ultimately help reduce mortality and morbidity in the US and India.