The effects of low calcium dialysate on arterial compliance and vasoactive substances in patients with hemodialysis

Considering that dialysate calcium concentration is potentially a main determinant of the serum ionized calcium level and vasoconstriction is associated with the blood calcium concentration, we conducted a study to evaluate the interdialytic effects of treatment with a low calcium dialysate (LdCa, 1.25 mmol/L) on the changes in arterial compliance (AC), blood pressure (BP), biochemical parameters and vasoactive substances. Eight hemodialysis (HD) patients (mean age: 46.8 +/- 13.7 years, 4 men and 4 women) were included in the study. AC, systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), mean arterial pressure (MAP), serum ionized Ca, intact-PTH, serum nitric oxide and aldosterone were compared after 10 sessions of treatment with LdCa. Right carotid artery diameter was measured 3 times using a real time B-mode ultrasound imager (Hewlett-Packard Sonos 2000) and AC was calculated using the Hayoz method. 1) AC was recorded as 0.140 (0.080-0.170) mm2/kPa at the baseline (1.75 mmol/L calcium dialysate), 0.170 (0.050-0.290) mm2/kPa after LdCa treatment (p < 0.05 versus baseline), and 0.140 (0.070-0.250) mm2/kPa following the HdCa treatment (p < 0.05 versus LdCa data). 2) MAP and PP were calculated at 114.12 +/- 10.56 mmHg and 63.50 +/- 10.87 mmHg at the baseline; 98.37 +/- 15.14 mmHg and 56.50 +/- 5.95 mmHg after LdCa treatment (p < 0.05 versus baseline); and 115.75 +/- 9.64 mmHg and 62.00 +/- 15.71 mmHg following HdCa treatment (p < 0.05 versus LdCa data). 3) Serum ionized Ca and intact-PTH were measured at 4.66 +/- 0.40 mg/dL and 25.08 +/- 16.44 pg/mL at the baseline; 4.45 +/- 0.28 mg/dL and 90.71 +/- 27.03 pg/mL after LdCa treatment (p < 0.05 versus baseline); and 4.65 0.43 mg/dL and 24.08 +/- 15.44 pg/mL following HdCa treatment (p < 0.05 versus LdCa data). 4) Serum aldosterone concentration was 300.8 (65.5-836.1) pg/mL at the baseline, and 220.2 (42.8-527.9) pg/mL after LdCa treatment (p < 0.05). There were favorable changes in AC, BP, biochemical parameters after treatment with LdCa. These changes may be associated with the reduction in serum ionized calcium and decreased serum aldosterone concentration.