Grant: Discovery Grants Program - Individual

Cardiovascular disease is the primary source of mortality globally. Existing diagnostic modalities are expensive and confined primarily to specialized labs. Often patients present to the hospital at a late stage of the disease, when the treatment options are limited. Thus, bringing diagnostics closer to the patient (e.g., primary care) is a proven way to diagnose a condition earlier, thus improving clinical outcomes, quality of care, patients' quality of life, and decreasing healthcare spending. Photoplethysmography (PPG) has the potential to become the tool of choice. PPG is an established noninvasive technology with several clinical applications (pulse oximetry as the most prolific case). In addition to clinical settings, novel PPG modalities (e.g., AppleWatch and Quora ring) rapidly penetrate digital health. With the wide adoption of PPG in medical practice (e.g. pulse oximeters), the technology development outpaces the science as there are still a lot of knowledge gaps. Therefore, current PPG technologies scratch only the surface of information embedded into the PPG signal. Namely, they focus primarily on blood oxygenation and heart rate detection. Thus, the current state of remote physiological imaging technology prompts the ubiquitous question of whether we can go beyond blood oxygenation and heart rate detection and extract additional macrocirculatory and microcirculatory information. That may significantly enhance the armamentarium for diagnostics, particularly in point-of-care settings. To accomplish it, a deep understanding of the mechanisms of pulse propagations and light interaction with tissue during the cardiac cycle is required. With a clear understanding of the PPG signal's origin, other PPG signal characteristics can be explored, and new technologies can be developed. Thus, the primary goal of the research program is to advance the understanding of the mechanisms of PPG signals in tissue. The secondary goal is to advance PPG technology for macro- and microvascular assessments. In particular, we will focus on applications of video plethysmography (VPG). VPG has several substantial advantages over traditional PPG. Firstly, it is a remote technology that allows measuring on sensitive skin or a wound bed, which is beyond of reach of PPG. However, the primary advantage is that, unlike traditional PPG single-point measurement technologies, VPG-based technologies can provide 2D health indicators maps, allowing spatiotemporal analysis. The program's scope is the balance between my scientific interests and practical applications, which are of interest to the industry and can be supported by the industry. The ultimate goal is to develop several automated clinical tools that can be used for rapid and objective vascular assessments performed at the bedside or in ambulatory settings. However, the project can be extended into multiple directions, technology- and clinically-wise, which will be explored during the project.