Unobtrusive and Affordable Blood Pressure Monitoring Via Pulse Transit Time

描述（由申请人提供）：高血压是一种可治疗的主要心血管危险因素，但在美国和印度的许多人中未被发现或控制。不显眼和负担得起的血压（BP）监测技术可以改善高血压的检测和控制，特别是在资源匮乏的环境中。实现这种技术的一个潜在途径是脉冲传输时间（PTT）。事实上，PTT与舒张血压相关，许多研究都证明了这一点，并且可以简单地从近端和远端动脉波形之间的相对时间来估计。但是，如何方便地测量两种波形，准确地估计PTT，将PTT校准为BP，以及从PTT确定收缩压仍然存在挑战。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、价格合理、高通量或个性化血压监测的技术。具体目标是：(1)开发廉价的系统，方便和准确地接触测量近端和远端动脉波形；(2)开发低成本的非接触测量近端和远端动脉波形的系统；(3)建立收缩期和舒张期PTT的高精度估计方法；(4)开发准确、便捷的PTT与BP校准系统；(5)对照人类参考血压测量值验证系统和方法。以称重秤、椅子和鞋子为形式的基于balllistocardiograph （BCG）的系统将被构建，并与光电容积脉搏仪（PPG）传感器接口，用于近端（BCG）和远端（PPG）波形的无缝测量。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PPG波形。动脉建模方法将被设计成从整个波形准确地估计PTT，而不是通过传统的脚到脚的时间延迟，在收缩期和舒张期。将设计物理振荡建模方法并将其与动脉建模方法相结合，使用袖带而不涉及操作员来构建准确的，特定于受试者的校准曲线，并且将创建回归方法来形成不使用袖带的校准曲线，仅使用基本受试者信息（例如年龄）。数据将从健康志愿者和听诊血压参考值的高血压门诊患者，以及一些血压不稳定的ICU高血压患者中收集，并放置导管作为金标准血压参考值。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，该技术将进行成本优化，并集成到智能手机中，以方便操作。这个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.