Preclinical Assessment of a Novel Cardiovascular Telemedicine System

Abstract

Background Introduction of telemonitoring systems to patient care which provide extensive information about the cardiovascular status of the patient is a promising direction to reduce cardiovascular morbidity and mortality. Our team has developed a telemedical system which is based on the photoplethysmographic detection of the digital arterial pulse wave. The system incorporates a cloud-based automated algorithm which analyses the pulse contour to provide 15 scientifically established parameters for versatile characterization of cardiovascular function. The aim of the current study was to assess the variability of the measurements to test the applicability of the tool before clinical use. We assessed the repeatability of the measurements by detecting stable artificial signals, and also test-retest variability by repeatedly examining the pulse contours of healthy individuals under standardized conditions. Results Most contour parameters (stiffness index, reflection index, left ventricular ejection time index and mean interbeat intervals) are measured with high repeatability (coefficients of variation (CV) < 1% for each parameter), and exhibit acceptable intrapersonal fluctuations (CVs < 10%). However, some parameters derived from the second derivative of the pulse wave seem to be more variable (aging index, d/a ratio). This is explained by the typical alterations of the pulse wave under specific circumstances, which cause the flattening or complete disappearance of c and d inflections on the second derivative. Conclusion Our measurements proved that our telemonitoring system detects and analyses digital pulse contours with high accuracy and highlighted that second derivative parameters should be interpreted cautiously. We recommend the evaluation of these parameters only in those measurements where c and d points are detected reliably. Pulse contour parameters are stable in healthy individuals under standardized conditions, which allows detection of subtle abnormal alterations by the remote surveillance system.

Multimodal Assessment of the Pulse Rate Variability Analysis Module of a Photoplethysmography-Based Telemedicine System

“…Therefore, filtering the signal does not affect the peak-to-peak distances of the pulse wave from which IBIs for PRV calculation are derived. Furthermore, in our previous article [ 40 ], we examined how artificial non-variable PPG signals generated by a simulator (both normal and simulated pathological signals) were processed by the system, and the repeatability was found to be perfect in case of most studied parameters [ 40 ]. Although this study focused on morphological parameters, we also investigated the reliability of IBI determination, and the error (expressed as coefficient of variation) was virtually zero.…”

“…Time series of IBI-PPG were used to calculate PRV parameters (for details, see data analysis). Data captured by the SCN4ALL system is stored on a cloud-based server equipped with safe data protection, which conforms to the applicable regulations ((EU)2016/679) [ 40 ].…”

“…Our research group has recently introduced a telemedical system (SCN4ALL) that is designed for the remote monitoring of cardiovascular patients and is based on the photoplethysmographic (PPG) detection and analysis of the digital arterial pulse wave [ 40 ]. The system analyzes continuous 2-min long PPG recordings, which are used to evaluate morphological pulse characteristics [ 40 ]. In order to offer the most benefit for our users, we have also elaborated an automated algorithm for PRV computation and equipped the telemedical system with a PRV analysis module.…”