Background: The primary aim of the international study DialysIS (Dialysis therapy between Italy and Switzerland) is the increased personalization of hemodialytic treatments through a modellistic approach. Within the DialysIS study, we investigated the use of a single-pool variable-volume Ca kinetic model to assess the intradialytic calcium mass balance (Ca2 + MB) in chronic and stable dialysis patients. Methods: 34 patients on thrice-weekly bicarbonate high-flux hemodialysis were studied during 240 dialysis sessions (mean 6.5 ± 1.9 for each patient; range 3–9). All patients were dialyzed with a nominal d[Ca] of 1.50 mmol/l. Ionized calcium concentrations of plasma water (Ca2 + pw) and dialysate (Ca2 + di) were determined at the beginning and end of each session; calcium dialysance (DCa) was estimated from conductivity dialysance. The most useful variable for validating this methodology was considered being the difference between end-dialysis ionized plasma water calcium concentration measured value, normalized to pH 7.40 (adjCa2 + pwtM), and predicted by the model (Ca2 + pwtP) applying: Ca2 + pwtP = 1/∙(Ca2 + di-(Ca2 + di–∙Ca2 + pw0)∙(VtCa/V0Ca) (DCa∙∙(1/Qfecv-1/Qpwi))) With  (Donnan’s factor) equal to 0.938. Results shown as mean ± standard deviation when normal, median (range) when non-normal. Results: A mean negative Ca2 + MB (–0.83 ± 1.33 mmol) and a statistically significant temporary parathyroid hormone (PTH) reduction was found (PTHt-PTH0: –128 (–488 ÷ 432) pg/ml p <0.01). Figure 1 shows the difference between the distribution of the predicted values, the adjusted values (Ca2+pwtP – adjCa2+pwtM: 0.016 (–0.08 ÷ 0.16) mmol/l)and the non-corrected values (Ca2+pwtP – Ca2+pwtM: 0.073 (–0.03 ÷ 0.20) mmol/l). Conclusions: The very low differences between predicted and adjusted Capwt suggest that it is possible to model and predict Ca2+MB during dialysis with a nominal dialysate calcium concentration of 1.5 mmol/l and a final calcium level in physiological range.

Preliminary results of dialysis study: single pool variable-volume calcium kinetic model

CASAGRANDE, GIUSTINA;BIANCHI, CAMILLA;COSTANTINO, MARIA LAURA;
2015-01-01

Abstract

Background: The primary aim of the international study DialysIS (Dialysis therapy between Italy and Switzerland) is the increased personalization of hemodialytic treatments through a modellistic approach. Within the DialysIS study, we investigated the use of a single-pool variable-volume Ca kinetic model to assess the intradialytic calcium mass balance (Ca2 + MB) in chronic and stable dialysis patients. Methods: 34 patients on thrice-weekly bicarbonate high-flux hemodialysis were studied during 240 dialysis sessions (mean 6.5 ± 1.9 for each patient; range 3–9). All patients were dialyzed with a nominal d[Ca] of 1.50 mmol/l. Ionized calcium concentrations of plasma water (Ca2 + pw) and dialysate (Ca2 + di) were determined at the beginning and end of each session; calcium dialysance (DCa) was estimated from conductivity dialysance. The most useful variable for validating this methodology was considered being the difference between end-dialysis ionized plasma water calcium concentration measured value, normalized to pH 7.40 (adjCa2 + pwtM), and predicted by the model (Ca2 + pwtP) applying: Ca2 + pwtP = 1/∙(Ca2 + di-(Ca2 + di–∙Ca2 + pw0)∙(VtCa/V0Ca) (DCa∙∙(1/Qfecv-1/Qpwi))) With  (Donnan’s factor) equal to 0.938. Results shown as mean ± standard deviation when normal, median (range) when non-normal. Results: A mean negative Ca2 + MB (–0.83 ± 1.33 mmol) and a statistically significant temporary parathyroid hormone (PTH) reduction was found (PTHt-PTH0: –128 (–488 ÷ 432) pg/ml p <0.01). Figure 1 shows the difference between the distribution of the predicted values, the adjusted values (Ca2+pwtP – adjCa2+pwtM: 0.016 (–0.08 ÷ 0.16) mmol/l)and the non-corrected values (Ca2+pwtP – Ca2+pwtM: 0.073 (–0.03 ÷ 0.20) mmol/l). Conclusions: The very low differences between predicted and adjusted Capwt suggest that it is possible to model and predict Ca2+MB during dialysis with a nominal dialysate calcium concentration of 1.5 mmol/l and a final calcium level in physiological range.
2015
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/973573
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