Calcium Profiling in Hemodiafiltration: A New Way to Reduce the Calcium Overload Risk without Compromising Cardiovascular Stability

Abstract

Background

Low and high dialysate calcium (Ca²⁺) content may have positive and harmful effects depending on the considered pathological aspect: hemodynamic instability, cardiac arrhythmias, parathormone release, adynamic bone disease, cardio-vascular calcifications. We hypothesized that a time-profiled Ca²⁺ concentration would keep the cardiovascular advantages of high Ca²⁺ but would reduce the risk of calcium overload.

Methods

A prospective, multicenter study using a particular hemodiafiltration technique that allows the profiling of electrolytes was designed. Patients (n = 22) underwent randomly a 3-week dialysis session with low and high constant dialysate Ca²⁺ (Ld_Ca, 1.25 mM and Hd_Ca, 2 mM) and profiled Ca²⁺ (Pd_Ca), respectively. Plasma and spent dialysate Ca²⁺, systolic and diastolic arterial pressure (SAP, DAP) and QT interval corrected for heart rate (QTc) were analyzed.

Results

Plasma Ca²⁺ concentration decreased in Ld_Ca, whereas it increased in Hd_Ca and to a lesser extent, in Pd_Ca. Total amount of Ca²⁺ given to the patient in Pd_Ca (15.5 ± 1.0 mmol) was higher than in Ld_Ca (4.3 ± 1.6 mmol) but lower than in Hd_Ca (21.9 ± 3.3 mmol). SAP and DAP decreased in Ld_Ca, whereas it was almost constant in both Hd_Ca and Pd_Ca. QTc significantly increased, up to critical values (>460 msec), only during Ld_Ca.

Conclusions

Pd_Ca seems to retain the advantages of high Ca²⁺ in terms of hemodynamic stability and modification of QTc while reducing the excessive positive calcium balance typical of dialysis with high Ca²⁺ content.