[SALUS] Remote monitoring of physiologic parameters and assessment of cardiovascular patients

Tese de Mestrado, Engenharia Biomédica e Biofísica, 2022, Universidade de Lisboa, Faculdade de CiênciasThis work describes the designing, prototyping and real-life testing of an Internet of Things (IoT) wearable device, the SALUS device. The solution consists of a purpose-built device, carefully designed for hospital use, that measures Heart Rate (HR), Blood Oxygen Saturation (SpO2), several Heart Rate Variability (HRV) parameters, Breathing Rate (BR) and Peripheral Vascular Resistance (PVR), and, therefore, acquiring most of the data needed for a cardiovascular patient evaluation. One of the critical challenges was the calculation of a novel way of assessing PVR using PPG. To do so, a regression analysis was performed between the Full Width at Half Maximum (FWHM) of the PPG peak and the value of PVR measured by the Task Force Monitor (TFM). Healthcare professionals, however, need more information to evaluate a cardiovascular patient than PVR alone, namely, HRV indexes. The SALUS device can provide these values by using the HeartPy library to analyse the data gathered. SALUS was tested in Hospital de Santa Marta following the 2008 Front-loaded Glyceryl Trinitrate (GTN) head-up tilt protocol used for the tilt test implemented in the Syncope Unit of the Hospital de Santa Marta and the results compared with the gold standard devices TFM and uMEC10, a cardiovascular monitor. There were limitations to this study since the number of patients considered was small and the sample was clinically heterogeneous. However, the main goal of this pilot study was to show that the SALUS device could be used in a clinical context. Despite the limitations, the results obtained were positive for the values of BPM (R 2=0.99), SpO2 (R 2=0.83), and LF/HF (R 2=0.77). The wearable device here developed holds promise to be a valuable and dependable diagnostic tool, as shown by the values when compared to the gold standard. Validation of this instrument is an ongoing process. Further testing and confirmation of other parameters are needed to assess the improvement of this acquisition for rapid screening of cardiac dysautonomia and Cardiovascular Disease (CVD)