Monitoring blood potassium concentration in hemodialysis patients by quantifying T-wave morphology dynamics

We investigated the ability of time-warping-based ECG-derived markers of T-wave morphology changes in time (d(w)) and amplitude (d(a)), as well as their non-linear components (d(w)(NL) and d(a)(NL)), and the heart rate corrected counterpart (d w,c), to monitor potassium concentration ([K+]) changes (Delta[K+]) in end-stage renal disease (ESRD) patients undergoing hemodialysis (HD). We compared the performance of the proposed time-warping markers, together with other previously proposed [K+] markers, such as T-wave width (T-w) and T-wave slope-to-amplitude ratio (T-S/A), when computed from standard ECG leads as well as from principal component analysis (PCA)-based leads. 48-hour ECG recordings and a set of hourly-collected blood samples from 29 ESRD- HD patients were acquired. Values of d(w), d(a), d(w)(NL), d(a)(NL) and d(w,c) were calculated by comparing the morphology of the mean warped T-waves (MWTWs) derived at each hour along the HD with that from a reference MWTW, measured at the end of the HD. From the same MWTWs T-w and T-S/A were also extracted. Similarly, Delta[K+] was calculated as the difference between the [K+] values at each hour and the [K+] reference level at the end of the HD session. We found that d w and d w,c showed higher correlation coefficients with Delta[K+] than TS/ A-Spearman's (rho) and Pearson's (r)-and T w-Spearman's (.)-in both SL and PCA approaches being the intra-patient median rho >= 0.82 and r >= 0.87 in SL and rho >= 0.82 and r >= 0.89 in PCA respectively. Our findings would point at d w and d w,c as the most suitable surrogate of Delta[K+], suggesting that they could be potentially useful for non-invasive monitoring of ESRD-HD patients in hospital, as well as in ambulatory settings. Therefore, the tracking of T-wave morphology variations by means of time-warping analysis could improve continuous and remote [K+] monitoring of ESRD-HD patients and flagging risk of [K+]-related cardiovascular events.

Automated summary

The study investigated the monitoring of potassium concentration changes in ESRD patients undergoing hemodialysis using time-warping analysis of ECG-derived T-wave morphology changes. It was found that d w and d w, c showed higher correlation coefficients with Delta[K+] than other proposed markers, suggesting their potential for non-invasive monitoring of ESRD-HD patients. Time-warping analysis of T-wave morphology variations could improve continuous and remote potassium monitoring and flagging risk of cardiovascular events in ESRD-HD patients.