目的:无创筛查低钾血症和高钾血症可以预防终末期肾病(ESRD)患者的致命性心律失常,但是目前监测血清钾(K+)的方法有重要的局限性。我们调查了血液透析(HD)期间ESRD患者心电图(ECG)中T波的非线性动力学和形态的变化,评估它们与K+的关系,并设计K+估计器。
方法:对29例接受HD的ESRD患者的心电图记录进行处理。在HD会话期间的每个小时以及HD开始后的48小时,在2分钟窗口中提取T波。T波非线性动力学的特征在于与最大Lyapunov指数相关的两个指数(λt,λwt)和发散相关指数(η)。通过三个基于时间翘曲的指数(dw,反映时域中的形态变异性,还有da和daNL,在振幅域中)。从HD期间和之后提取的血液样品测量K+。基于量化指数建立阶段特异性和患者特异性K+估计器,并对每个估计器分别进行留一法交叉验证。
结果:分析的指标在与K+的关系中显示出高度的个体间变异性。然而,所有这些在HD开始和48小时后都有更高的值,对应于最高的K+。指数η和dw与K的相关性最强(中位皮尔逊相关系数分别为0.78和0.83),并用于单变量和多变量线性K估计。确认了实际K+和估计K+之间的协议,对于阶段特异性和患者特异性多变量K+估计器,患者和时间点的平均误差为0.000±0.875mM和0.046±0.690mM,分别。
结论:T波非线性动力学和形态学变异性的ECG描述符允许对ESRD患者的K+进行无创监测。
结论:心电图标志物有可能用于ESRD患者的低钾血症和高钾血症筛查。
OBJECTIVE: Noninvasive screening of hypo- and hyperkalemia can prevent fatal arrhythmia in end-stage renal disease (ESRD) patients, but current methods for monitoring of serum potassium (K+) have important limitations. We investigated changes in nonlinear dynamics and morphology of the T wave in the electrocardiogram (ECG) of ESRD patients during hemodialysis (HD), assessing their relationship with K+ and designing a K+ estimator.
METHODS: ECG recordings from twenty-nine ESRD patients undergoing HD were processed. T waves in 2-min windows were extracted at each hour during an HD session as well as at 48 h after HD start. T wave nonlinear dynamics were characterized by two indices related to the maximum Lyapunov exponent (λt, λwt) and a divergence-related index (η). Morphological variability in the T wave was evaluated by three time warping-based indices (dw, reflecting morphological variability in the time domain, and da and daNL, in the amplitude domain). K+was measured from blood samples extracted during and after HD. Stage-specific and patient-specific K+ estimators were built based on the quantified indices and leave-one-out cross-validation was performed separately for each of the estimators.
RESULTS: The analyzed indices showed high inter-individual variability in their relationship with K+. Nevertheless, all of them had higher values at the HD start and 48 h after it, corresponding to the highest K+. The indices η and dw were the most strongly correlated with K+ (median Pearson correlation coefficient of 0.78 and 0.83, respectively) and were used in univariable and multivariable linear K+ estimators. Agreement between actual and estimated K+ was confirmed, with averaged errors over patients and time points being 0.000 ± 0.875 mM and 0.046 ± 0.690 mM for stage-specific and patient-specific multivariable K+ estimators, respectively.
CONCLUSIONS: ECG descriptors of T wave nonlinear dynamics and morphological variability allow noninvasive monitoring of K+ in ESRD patients.
CONCLUSIONS: ECG markers have the potential to be used for hypo- and hyperkalemia screening in ESRD patients.