Figure 5
PCA-based time-warping markers and RR interval time trends. An example for a given patient undergoing 4h-long HD therapy, is depicted in panel (a) with the evolution of \(d_{w}\) (filled green squares), \({\hat{d}}_{w,c}\) (filled orange squares), both referring to the left vertical scale, and the average RR intervals (unfilled dark red squares, referring to the right vertical scale). \(\Delta [K^{+}]\) relative variations with respect to the concentration at HD end (purple diamonds) are expressed in mmol/L. Time is expressed in hours from the beginning of the treatment onward. Each square denotes the mean RR interval in a 2-min wide segment used to compute the warping parameters, while the highlighted blue square corresponds to the reference segment at the end of HD. The filled red square denotes the time-point from which the studied MWTW in Fig. 2b was selected. Note that for this patient, the Holter recording did not reach the planned 48h. Panel (b) shows the median and IQR for each observing i-th segment, computed by using the values from all the available patients for \(d_{w}^{u}\), \(d_w\) and \({\hat{d}}_{w,c}\) and \(d_{w}^{\mathrm{NL}}\) (this latter refers to the right axis, while the others to the left). Time trends (expressed as median and IQR) for \(d_{a}\) and \(d_{a}^{\mathrm{NL}}\), referring to the left and right axes respectively are in panel (c). Panels (b) and (c) give an overview of the time evolution for these biomarkers along the ECG acquisition from the HD beginning onward. Only the first 44 h were depicted being that the average ECG duration in our database.
