Measurements of pulse rate using facial video cameras from smart devices in patients diagnosed with atrial fibrillation.

Clinical applications of passive long-term heart rate (HR) monitoring in patients with cardiac arrhythmias include adequate drug titration of atrioventricular (AV) nodal drugs and assessment of medical compliance with treatment. A majority of patients treated with beta-blockers, especially patients with atrial fibrillation (AF), require some degree of drug titration during the first 6 months of treatment to ensure that adequate HR control and medicine compliance has been achieved. Failing to achieve adequate rate control in patients with AF can lead to worsening symptoms, heart failure exacerbations, and potentially tachycardia-induced cardiomyopathy. Enabling video-based monitoring during telehealth patient visits could facilitate providers to measure heart rate (HR) without the need for a dedicated home device (smartwatch, SPO2 device, or others). Videoplethysmography (VPG) is a monitoring technology that measures pulse rate by utilizing front-facing cameras embedded in smart devices. VPG provides a remote and contactless cardiac monitoring solution. We conducted a clinical experiment to evaluate the accuracy of VPG in measuring HR while running on two portable devices: Samsung S10 smartphones and S3 tablets. We used a single­lead ECG to measure the heart rate at the time of the VPG recordings in AF patients. We employed the Bland-Altman method to measure the level of agreement between videoplethysmography and ECG-based measurements of HR. The findings reveal that the mean difference in videoplethysmography and ECG-based heart rate was inferior to 1 bpm across the 2 devices with confidence intervals ranging from 3 to 12 BPM. Our facial video-based HR monitoring solution could assist providers in measuring heart rates in their patients with AF during remote telehealth visits.

An investigation into relaying of creeping waves for reliable low-power body sensor networking.

We investigate the use of relaying of creeping waves in the industrial scientific medical frequency bands of 434 MHz, 915 MHz, and 2.4 GHz. The investigation includes generic analysis and experimental setups. For generic analysis, a link budget model is derived based solely on the creeping wave component of the transmitted signal while marginalizing for other effects, such as reflections from the surrounding environment. Closed-form expressions of the gains in network lifetime and energy per bit are derived for a system covering the entire body using relays compared to a reference system offering the same level of reliability without relaying. The experimental setups are used to gather measurements in the 2.4-GHz band with a body sensor network development platform in a nonreflective open-space environment and in a reflective residential environment. The measurements are used to validate the link budget model and evaluate performance of practical systems. Analysis and experimentation demonstrate that relaying of creeping waves offers considerable performance gains in all frequency bands. For example, using a single relay on either side of the body in 2.4 GHz can potentially increase network-lifetime times 40 and decrease energy per bit by 48 dB. Part of this potential is achieved in experimental setups where relaying was shown to increase network lifetime times 13, decrease energy per bit by 13 dB and provide the ability to compensate for a wider fading margin.