Edema detection for heart failure patients in home monitoring scenarios

Heart failure consumes 2% of Austria's health budget. Re-hospitalization rates within 6 months after discharge are about 50% and earlier studies showed that even telemonitoring can only avoid up to 50% of these re-hospitalizations. Since leg edemas are a typical symptom, it was our aim to further reduce this rate, using new methods for edema detection. An existing telemonitoring system was extended by a 3D camera in order to geometrically detect and quantify leg edemas. 3D images were taken and instep height and leg curvature, were calculated. We present the results of the first evaluation step - a feasibility test, comparing relative intra-subject variations. A total of 87 measurements at different times of day within four consecutive days were performed for five healthy subjects. Relative intra-subject variation V_rel was 2.89±0.90% for instep height and 8.32±0.77% for leg curvature. Our results indicate that by 3D imaging, the geometry of a person's foot can be measured with errors that are far lower than changes expected in case of edemas. Instep height and leg curvature were found to be reliable parameters for the monitoring of legs. Future work will investigate whether edemas can be detected by our method and evaluate the concept's usability in a real-life home monitoring scenario.