Evaluation of a new online hemodiafiltration mode with automated pressure control of convection.

BACKGROUND: Postdilution hemodiafiltration (HDF) still remains the gold standard for solute removal, but with high hemoglobin levels transmembrane pressure (TMP) may reach high levels, reducing filter performance. We compared three online postdilution HDF treatments without TMP alarms for convective volume and plasma changes following treatment. METHODS: Twelve patients were enrolled in a trial with three online postdilution HDF treatments. In the volume-controlled mode (VOLc), we set the exchanged volume to obtain a filtration fraction close to 25% without TMP alarms. In the pressure-controlled mode (TMPc), we set the TMP at 100 mm Hg. In the ULTRAc mode (TMP scan combined with TMPc), the dialysis machine automatically selects the TMP with a scan. All treatments were performed with an AK200 ULTRA-S system. RESULTS: Even with hemoglobin levels >12 g/dl, we found a 57% rise in ultrafiltration rate in TMPc versus VOLc and a 92% rise in ULTRAc versus VOLc. Phosphates and myoglobin levels were significantly affected by treatment type. CONCLUSIONS: ULTRAc may be a useful tool to achieve an excellent purification performance without the constraints associated with the risk of hemoconcentration.

Kinetics of hepatitis B virus load and haemodialysis: a prospective study.

The control of the spread of hepatitis B virus (HBV) infection within dialysis units has been an important goal in the management of patients on regular dialysis but infected patients continue to enter the dialysis system. It is evident that HBV viraemia in hepatitis B surface antigen (HBsAg)-positive patients on dialysis is low but it remains unclear whether haemodialysis per se can contribute to viral load reduction in such patients. HBV DNA was determined in 40 HBsAg-positive patients on maintenance haemodialysis immediately before and at the end of a 4-h haemodialysis session. The same measurements were repeated 48 and 72 h later. Twenty (50%) of 40 HBsAg-positive patients had detectable HBV DNA in serum. Detectable HBV DNA in serum was not predicted by demographic, clinical or biochemical parameters. HBV load decreased in the majority of patients after haemodialysis, although the difference was not significant (29 390 +/- 48 820 vs 23 862.8 +/- 4 350 copies/mL, NS). There was a strong relationship between mean HBV DNA levels before dialysis and absolute reduction of HBV DNA during haemodialysis sessions (r = 0.75, P = 0.0001). No difference occurred in the magnitude of change in HBV DNA titre when comparing cellulosic to synthetic membranes. Haemodialysis per se leads to a reduction in HBV load in HBsAg-chronic carriers on maintenance dialysis. This phenomenon could explain the low viral loads in these patients. Prospective studies are in progress to identify the mechanisms responsible for reduction in HBV load during haemodialysis.

A new method to evaluate patient characteristic response to ultrafiltration during hemodialysis.

BACKGROUND: Several factors are involved in the pathogenesis of dialysis discomfort interfering with optimal fluid removal and reducing the efficacy of the treatment; the most important one is a decrease in blood volume caused by an imbalance between ultrafiltration (UF) and plasmarefilling (PR) rates. OBJECTIVES: This study is aimed at devising a method to tailor the dialysis therapy to each individual patient, by analyzing the relationship between PR and UF during the sessions in stable patients and widening the knowledge of fluid exchanges during the treatment. METHODS: Thirty stable patients undergoing maintenance hemodialysis were enrolled. Three dialysis sessions were monitored for each patient; systemic pressure, blood composition, blood volume % variation, weight loss and conductivity were recorded repeatedly. A Plasma Refilling Index (PRI), defined and calculated by means of parameters measured throughout the dialysis, was introduced as a novel instrument to study plasma refilling phenomena. Results. The PRI provides understanding of patient response (in terms of plasma refilling) to the set UF. In the monitored sessions, the PRI trend is found to be characteristic of each patient; a PRI course that is at variance with the characteristic trend is a signal of inadequate or unusual dialysis scheduling. Moreover, statistical analysis highlights two different PRI trends during the first hour and during the rest of the treatment, suggesting the presence of different treatment phases. CONCLUSION: The main advantage of the PRI index is that it is non-invasive peculiar to each patient and easy to compute in a dialysis routine based on online data recorded by the monitor. A deviation from the characteristic trend may be a warning for the clinician. The analysis of the PRI trend also suggests how to modulate UF as a function of interstitial to intravascular fluid removal balance during dialysis.

Microcirculation as a novel marker of membrane biocompatibility.

BACKGROUND: It is possible to consider microcirculation as a kind of OwitnessO of the complex biological reactions triggered by the dialytic treatment. The reactivity of microcirculation to the dialytic stress may represent a measure of the overall biocompatibility of the membrane. In this study we tested the hypothesis that different synthetic membranes may have different biological effects, particularly related to microcirculation. SUBJECTS AND METHODS: In this crossover study, we observed 16 chronically hemodialyzed patients. All patients were treated with the EVAL membrane; we recorded the TcPO2 during the second treatment of the week. All patients were then switched to the hf-PS membrane. During the study observation we did not change the dialytic prescription or the pharmacologic treatment. RESULTS: From the beginning of the session until 90O, the behavior of TcPO2 is similar for both the membranes. From 120O to the end of the treatment in sessions with the EVAL membrane, the TcPO2 values come back to the starting level, whereas in the treatments with hf-PS the TcPO2, the values remain at a lower level; there was a significant difference between EVAL and hf-PS in the values recorded. Arterial blood gas values of paO2 and paCO2 are quite similar in the treatments with both the membranes, without any significant difference. CONCLUSIONS: The analysis of microcirculation by means of TcPO2 measurement is a useful tool to obtain a OclinicalO measure of biocompatibility of the dialytic treatment and different membranes may have different impacts on TcPO2.

Dislipemia in patients undergoing continuous ambulatory peritoneal dialysis: pharmacological therapy (simvastatin) versus hemodialysis.

Peritoneal dialysis can worsen dislipemia, which is frequent in chronically uremic patients. In order to verify the therapeutic possibilities, we retrospectively studied 20 chronically uremic patients who had been previously treated with continuous ambulatory peritoneal dialysis (CAPD) and who had developed an IV-type dislipemia. Twelve have continued CAPD treatment and have been simultaneously treated with simvastatin; 8 have withdrawn from CAPD and have begun HD, without any antidislipemic pharmacological support. The results, after 3, 6, 12, and 18 months of treatment, showed the following: in patients treated with CAPD and simvastatin, highly significant decreases were noted in total cholesterol (T-cho) and triglycerides (TG) (p < 0.001), and highly significant increases were noted in HDL-cholesterol (HDL-cho) (p < 0.005) and apolipoprotein-A1 (Apo-A1) (p < 0.01). In patients treated with HD, only slightly significant decreases were noted in T-cho (p < 0.01) and TG (p < 0.02), a slightly significant increase in Apo-A1 (p < 0.05), and no significant change in HDL-cho. Apolipoprotein-B showed no change in the two groups. Therefore, patients undergoing CAPD, with dislipemia only, can continue the treatment, because simvastatin is capable of correcting dislipemia, while those patients who have displemia as well as other complications strictly due to CAPD must abandon treatment and must be transferred to extracorporeal methods.