Calcium profiling in hemodiafiltration: a new way to reduce the calcium overload risk without compromising cardiovascular stability.

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.