The dialysis staff workload and the blood volume tracking system during the hemodialysis sessions of hypotension-prone patients.

PURPOSE: Intradialytic hypotension (IDH) represents a common hemodialysis (HD) complication. Blood volume tracking (BVT) is a tool regulating the relative blood volume changes and potentially reducing the occurrence of IDH. The aim of this study was to evaluate the ability of BVT to reduce the staff workload associated to IDH. METHODS: Ten hypotension-prone HD patients were treated each with 39 conventional HD (HD) sessions and then switched to 39 HD sessions with BVT (HD-BVT). The staff interventions related to IDH were monitored by a trained staff. RESULTS: Dialysis sessions complicated by IDH and staff interventions were affected by BVT (HD: 102 and 127 vs. HD-BVT: 57 and 59, respectively, for both p<0.001). The time consumed by staff in IDH management was decreased by HD-BVT (1416 vs. 578 min, p<0.001). CONCLUSIONS: The effectiveness of BVT to reduce the frequency of IDH leads to a reduction of the dialysis staff workload with fewer staff interventions, allowing for major work-time saving.

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

BACKGROUND: Low and high dialysate calcium (Ca²âº) 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 Ca²âº concentration would keep the cardiovascular advantages of high Ca²âº 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 Ca²âº (Ld(Ca,), 1.25 mM and Hd(Ca,), 2 mM) and profiled Ca²âº (Pd(Ca)), respectively. Plasma and spent dialysate Ca²âº, systolic and diastolic arterial pressure (SAP, DAP) and QT interval corrected for heart rate (QTc) were analyzed. RESULTS: Plasma Ca²âº concentration decreased in Ld(Ca), whereas it increased in Hd(Ca) and to a lesser extent, in Pd(Ca). Total amount of Ca²âº 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 Ca²âº in terms of hemodynamic stability and modification of QTc while reducing the excessive positive calcium balance typical of dialysis with high Ca²âº content.

Divert to ULTRA: differences in infused volumes and clearance in two on-line hemodiafiltration treatments.

BACKGROUND: Mixed diffusive-convective dialysis therapies offer greater removal capabilities than conventional dialysis. The aim of this study was to compare two different on-line, post-dilution hemodiafiltration (HDF) treatments with regard to achieved convective volume and middle-molecule dialysis efficiency: standard volume control (sOL-HDF) and automated control of the transmembrane pressure (TMP) (UC-HDF). METHODS: We enrolled 30 ESRD patients (55.9 ± 14.0 years, 20/10 M/F) in a randomized, prospective, cross-over study. The patients received a 3-month period of sOL-HDF followed by UC-HDF for a further 3 months, or vice versa, using the same dialysis machine. In sOL-HDF, fixed exchange volumes were set according to a filtration fraction greater than or equal to 25%. In UC-HDF therapy, the exchanged volume was driven by a biofeedback system controlling the TMP and its set point in a double loop. Patients maintained their treatment time, dialyzer, blood flow rate, and anticoagulant regimen unchanged throughout the study. RESULTS: Greater convective volumes were achieved in UC-HDF than in sOL-HDF (23.8 ± 3.9 vs.19.8 ± 4.8 L; p<0.001) with high pre-dialysis Ht value (sOL-HDF 34.0 ± 4.5% and UC-HDF 34.0 ± 4.4%; p = 0.91). The average clearance values of ß2m and P were higher in UC-HDF than in sOL-HDF (respectively 123 ± 24 vs. 111 ± 22 ml/min, p<0.002 and 158 ± 26 vs. 152 ± 25 ml/min, p<0.05). Moreover, the UC-HDF mode led to a significantly increased rate of call-free sessions from 88% to 97% (p<0.0001). CONCLUSIONS: This study showed that the biofeedback module, applied to the automatic control of TMP in on-line HDF, results in higher convective volumes and correspondingly higher ß2m and P clearances. By making the HDF treatment more automated and less complex to perform, it significantly reduced the staff workload.

Simple model of intra-extracellular potassium kinetics and removal applied to constant and potassium-profiled dialysis.

AIM: The incidence rate for sudden death in hemodialysis patients ranges between 2% and 7%. This phenomenon is frequently due to cardiac arrhythmias. In particular, the process of potassium (K(+)) depuration performed during hemodialysis has been found to be related to arrhythmia onset. The main aim of this study was to introduce a simple double-pool mathematical model of K(+) kinetics to investigate the effects of dialysate K(+) concentration on intracellular and extracellular K(+) removal. The secondary aim was to evaluate the K(+) removed from the different body pools in 2 different types of K(+) dialysate: constant and profiled. METHODS: Our model evaluated K(+) removal and body water in the intracellular and extracellular spaces using plasma, erythrocytes and spent dialysate K(+) concentration, and intracellular and extracellular volume (t=0) in 6 patients (4 females and 2 males). All patients were treated with acetate-free biofiltration with a constant K(+) dialysate concentration (AFB) and with a profiled one (AFB-K). Moreover, the electrolyte concentration (sodium, calcium and bicarbonate) and pH were analyzed in all sessions. RESULTS: A similar total potassium removal was evaluated by the model, starting from a similar final K(+) plasma reduction. At 10 minutes, the model assessed a higher K(+) removal in the extracellular space during AFB (26.6% vs. 7.7%, p<0.001) involving a lower K(+) concentration (5.0 +/- 0.5 in AFB and 5.2 +/- 0.6 in AFB-K, p<0.05) and consequently a higher cell hyperpolarization (-73.4 +/- 3.9 mV vs. -72.1 +/- 2.4 mV, p=0.05). No differences in pH, intracellular and extracellular Na+ or plasma Ca(2+) were highlighted between AFB and AFB-K. CONCLUSIONS: The model we developed allows us to evaluate K(+) removal and body water in the intracellular and extracellular spaces during treatment. The assessment of this information may have a relevant role toward an understanding of the causes of the Nernst potential changes during hemodialysis that are often related to the onset of arrhythmias.