Bolasco Piergiogio, Concas Gabriella, Steckiph Denis, Grandi Fabio, Polacchini Maurizio
Regional Specialist Unit of Nephrology and Dialysis, Azienda USL N. 8 di Cagliari, Cagliari, Italy.
J Nephrol. 2008 May-Jun;21(3):384-93.
The incidence rate for sudden death in hemodialysis patients ranges between 2% and 7%. This phenomenon is frequently due to cardiac arrhythmias. In particular, the process of potassium (K(+)) depuration performed during hemodialysis has been found to be related to arrhythmia onset. The main aim of this study was to introduce a simple double-pool mathematical model of K(+) kinetics to investigate the effects of dialysate K(+) concentration on intracellular and extracellular K(+) removal. The secondary aim was to evaluate the K(+) removed from the different body pools in 2 different types of K(+) dialysate: constant and profiled.
Our model evaluated K(+) removal and body water in the intracellular and extracellular spaces using plasma, erythrocytes and spent dialysate K(+) concentration, and intracellular and extracellular volume (t=0) in 6 patients (4 females and 2 males). All patients were treated with acetate-free biofiltration with a constant K(+) dialysate concentration (AFB) and with a profiled one (AFB-K). Moreover, the electrolyte concentration (sodium, calcium and bicarbonate) and pH were analyzed in all sessions.
A similar total potassium removal was evaluated by the model, starting from a similar final K(+) plasma reduction. At 10 minutes, the model assessed a higher K(+) removal in the extracellular space during AFB (26.6% vs. 7.7%, p<0.001) involving a lower K(+) concentration (5.0 +/- 0.5 in AFB and 5.2 +/- 0.6 in AFB-K, p<0.05) and consequently a higher cell hyperpolarization (-73.4 +/- 3.9 mV vs. -72.1 +/- 2.4 mV, p=0.05). No differences in pH, intracellular and extracellular Na+ or plasma Ca(2+) were highlighted between AFB and AFB-K.
The model we developed allows us to evaluate K(+) removal and body water in the intracellular and extracellular spaces during treatment. The assessment of this information may have a relevant role toward an understanding of the causes of the Nernst potential changes during hemodialysis that are often related to the onset of arrhythmias.
血液透析患者的猝死发生率在2%至7%之间。这种现象通常归因于心律失常。特别是，已发现血液透析期间进行的钾（K⁺）净化过程与心律失常的发作有关。本研究的主要目的是引入一个简单的K⁺动力学双池数学模型，以研究透析液K⁺浓度对细胞内和细胞外K⁺清除的影响。次要目的是评估在两种不同类型的K⁺透析液（恒定型和曲线型）中从不同身体池清除的K⁺。
我们的模型使用血浆、红细胞和用过的透析液K⁺浓度以及6名患者（4名女性和2名男性）的细胞内和细胞外体积（t = 0）来评估细胞内和细胞外空间中的K⁺清除和身体水分。所有患者均接受无醋酸盐生物滤过治疗，透析液K⁺浓度恒定（AFB）和曲线型（AFB-K）。此外，在所有治疗过程中分析电解质浓度（钠、钙和碳酸氢盐）和pH值。
从相似的最终血浆K⁺降低开始，模型评估的总钾清除量相似。在10分钟时，模型评估AFB期间细胞外空间的K⁺清除率更高（26.6%对7.7%，p<0.001），这涉及较低的K⁺浓度（AFB中为5.0±0.5，AFB-K中为5.2±0.6，p<0.05），因此细胞超极化程度更高（-73.4±3.9 mV对-72.1±2.4 mV，p = 0.05）。AFB和AFB-K之间在pH值、细胞内和细胞外Na⁺或血浆Ca²⁺方面未发现差异。
我们开发的模型使我们能够评估治疗期间细胞内和细胞外空间中的K⁺清除和身体水分。对这些信息的评估可能对理解血液透析期间能斯特电位变化的原因具有重要作用，这些变化通常与心律失常的发作有关。
