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+ (LdCa, 1.25 mM and HdCa, 2 mM) and profiled Ca2+ (PdCa), 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 LdCa, whereas it increased in HdCa and to a lesser extent, in PdCa. Total amount of Ca2+ given to the patient in PdCa (15.5 ± 1.0 mmol) was higher than in LdCa (4.3 ± 1.6 mmol) but lower than in HdCa (21.9 ± 3.3 mmol). SAP and DAP decreased in LdCa, whereas it was almost constant in both HdCa and PdCa. QTc significantly increased, up to critical values (>460 msec), only during LdCa. Conclusions PdCa 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.