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.
Hypertension is a major cardiovascular risk factor that is treatable, but often undetected or uncontrolled, especially in low resource settings. Ultra-convenient and cheap blood pressure monitoring technologies will be established to markedly improve hypertension detection and control.
|Chandrasekhar, Anand; Kim, Chang-Sei; Naji, Mohammed et al. (2018) Smartphone-based blood pressure monitoring via the oscillometric finger-pressing method. Sci Transl Med 10:|
|Kim, Chang-Sei; Carek, Andrew M; Inan, Omer T et al. (2018) Ballistocardiogram-Based Approach to Cuffless Blood Pressure Monitoring: Proof of Concept and Potential Challenges. IEEE Trans Biomed Eng 65:2384-2391|
|Chandrasekhar, Anand; Natarajan, Keerthana; Yavarimanesh, Mohammad et al. (2018) An iPhone Application for Blood Pressure Monitoring via the Oscillometric Finger Pressing Method. Sci Rep 8:13136|
|Etemadi, Mozziyar; Inan, Omer T (2018) Wearable ballistocardiogram and seismocardiogram systems for health and performance. J Appl Physiol (1985) 124:452-461|
|Mukkamala, Ramakrishna; Hahn, Jin-Oh (2018) Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Predictions on Maximum Calibration Period and Acceptable Error Limits. IEEE Trans Biomed Eng 65:1410-1420|
|Liu, Jiankun; Cheng, Hao-Min; Chen, Chen-Huan et al. (2017) Patient-Specific Oscillometric Blood Pressure Measurement: Validation for Accuracy and Repeatability. IEEE J Transl Eng Health Med 5:1900110|
|Gao, Mingwu; Cheng, Hao-Min; Sung, Shih-Hsien et al. (2017) Estimation of Pulse Transit Time as a Function of Blood Pressure Using a Nonlinear Arterial Tube-Load Model. IEEE Trans Biomed Eng 64:1524-1534|
|Wiens, Andrew D; Johnson, Ann; Inan, Omer T (2017) Wearable Sensing of Cardiac Timing Intervals from Cardiogenic Limb Vibration Signals. IEEE Sens J 17:1463-1470|
|Ashouri, Hazar; Inan, Omer T (2017) Automatic Detection of Seismocardiogram Sensor Misplacement for Robust Pre-Ejection Period Estimation in Unsupervised Settings. IEEE Sens J 17:3805-3813|
|Carek, Andrew M; Inan, Omer T (2017) Robust Sensing of Distal Pulse Waveforms on a Modified Weighing Scale for Ubiquitous Pulse Transit Time Measurement. IEEE Trans Biomed Circuits Syst 11:765-772|
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