Assessment of intradialysis calcium mass balance by a single pool variable-volume calcium kinetic model.

Introduction: A reliable method of intradialysis calcium mass balance quantification is far from been established. We herein investigated the use of a single-pool variable-volume Calcium kinetic model to assess calcium mass balance in chronic and stable dialysis patients.

Methods: Thirty-four patients on thrice-weekly HD were studied during 240 dialysis sessions.

Optimizing haemodialysate composition.

Survival and quality of life of dialysis patients are strictly dependent on the quality of the haemodialysis (HD) treatment. In this respect, dialysate composition, including water purity, plays a crucial role. A major aim of HD is to normalize predialysis plasma electrolyte and mineral concentrations, while minimizing wide swings in the patient's intradialytic plasma concentrations.

Prospective randomized pilot study on the effects of two synthetic high-flux dialyzers on dialysis patient anemia.

Purpose: Anemia in chronic kidney disease dialysis patients is a complex syndrome involving many causes. Adequate dialysis can contribute to its correction through many mechanisms, including the removal of molecules that may inhibit erythropoiesis. The aim of this pilot study was to evaluate the effect on renal anemia of two synthetic, high-flux dialyzers (polynephron vs.

Effect of a plasma sodium biofeedback system applied to HFR on the intradialytic cardiovascular stability. Results from a randomized controlled study.

Background: Intradialytic hypotension (IDH) is still a major clinical problem for haemodialysis (HD) patients. Haemodiafiltration (HDF) has been shown to be able to reduce the incidence of IDH.

Methods: Fifty patients were enrolled in a prospective, randomized, crossover international study focussed on a variant of traditional HDF, haemofiltration with endogenous reinfusion (HFR).

Automatic adaptive system dialysis for hemodialysis-associated hypotension and intolerance: a noncontrolled multicenter trial.

Background: Hemodialysis is complicated by a high incidence of intradialytic hypotension and disequilibrium symptoms caused by hypovolemia and a decrease in extracellular osmolarity. Automatic adaptive system dialysis (AASD) is a proprietary dialysis system that provides automated elaboration of dialysate and ultrafiltration profiles based on the prescribed decrease in body weight and sodium content.

Study Design: A noncontrolled (single arm), multicenter, prospective, clinical trial.

Management of anemia by convective treatments.

Anemia secondary to chronic kidney disease is a complex syndrome. Adequate dialysis can contribute to its correction by removing small and possibly medium/large molecules that may inhibit erythropoiesis. A clear relationship among hemoglobin, erythropoiesis stimulating agent (ESA) dose and increase in dialysis dose has been pointed out by a number of prospective and retrospective studies.

Hemodiafiltration - state of the art.

Many observational studies have consistently shown that high-flux hemodialysis (hf-HD) has positive effects on the survival and morbidity of chronic kidney disease stage 5 dialysis (CKD5D) patients when compared with low-flux hemodialysis, but the primary analysis of the prospective randomized Hemodialysis Outcomes (HEMO) study showed that the use of hf-HD was not associated with a significant reduction of the relative risk of mortality. More recently, the Membrane Permeability Outcome (MPO) study found that survival could be significantly improved by use hf-HD compared with low-flux dialysis in high-risk patients as identified by serum albumin ≤4 g/dl and, in a post-hoc analysis, in diabetic patients. Online hemodiafiltration (HDF) is reported as the most efficient technique of using high-flux membranes.

Effect of synthetic vitamin E-bonded membrane on responsiveness to erythropoiesis-stimulating agents in hemodialysis patients: a pilot study.

Background: Oxidative stress, a recently identified factor related to the response to erythropoiesis-stimulating agents (ESAs), is increased in hemodialysis patients. The aim of this study was to verify whether ESA responsiveness improves if the anti-oxidant vitamin E (Vi-E) is placed on the blood-side layer of a synthetic polysulfone (PS) dialyzer.

Methods: This 8-month, controlled and open randomized study involved 2 groups of patients on stable ESA therapy undergoing hemodialysis using a PS dialyzer with or without Vi-E treatment.

Can convective therapies improve dialysis outcomes?

Purpose Of Review: Convective treatments are characterized by enhanced removal of middle and large molecular weight solutes, important in the genesis of many complications of hemodialysis, compared with conventional low-flux hemodialysis. The availability of these techniques represented an intriguing innovation and a possible means to improve the still poor prognosis of hemodialysis patients. In this study we will critically review the most important published studies evaluating the impact of convective treatments on dialysis outcomes.

Membrane characteristics.

Dialysis membrane characteristics are important for an effective and biocompatible dialysis. The properties of a membrane determine the size range of uremic toxins that are eliminated, but are also associated to patient morbidity and mortality. In this paper we describe dialysis the membrane characteristics that could influence the choice of a different type of dialysis.

Dialysate composition.

The most appropriate dialysate composition is one of the central topics in dialysis treatment. The prescription of a certain dialysate composition could change in order to obtain not only an adequate blood purification but also a high tolerability. Sodium balance represents the cornerstone of cardiovascular stability and good blood pressure control.

Clinical aspects of haemodiafiltration.

Standard haemodialysis is not a very efficacious treatment of chronic uraemia and patient mortality rate is still very high. The 2002 results of the HEMO study showed that alternative treatments such as 'high-efficiency haemodialysis' and 'high-flux haemodialysis' are associated with a non-significant reduction in the relative risk of mortality (4 and 8%, respectively). In an attempt to define the clinical impact of haemodiafiltration, we review some of the efficacy data from clinical studies in light of a number of factors that may be related to the high mortality among haemodialysis patients.

Effectiveness of sodium and conductivity kinetic models in predicting end-dialysis plasma water sodium concentration: preliminary results of a single-center experience.

The attainment of a neutral sodium balance represents a major objective in hemodialysis patients. It requires that at the end of each dialysis session, total body water volume (V(f)) and total plasma water sodium concentration (Na(pwf)) are constant. Whereas to achieve a constant V(f) it is sufficient that ultrafiltration equals the interdialytic increase in body weight, it is impossible to predict the value of Na(pwf) and calculate the dialysate sodium concentration needed to obtain it without making use of kinetic mathematical models.

A critical assessment of uremia research.

There are considerably fewer randomized controlled trials investigating hemodialysis (HD) than other fields of internal medicine, and no significant improvements have been observed over time. Only the National Cooperative Dialysis Study and the HEMO trial were based on hard endpoints such as morbidity and mortality, but neither considered on-line hemodiafiltration or super-flux membranes, which are thought to provide a number of advantages in terms of the cardiovascular condition of uremic patients. However, results of well-designed clinical trials showing that increasing convection may improve the clinical outcome of HD patients are still lacking.

Relationship between urea clearance and ionic dialysance determined using a single-step conductivity profile.

Background: On-line determination of ionic dialysance (ID) has been used to measure the clearance of small solutes like urea. However, attempts to determine the in vivo relationship between ID and urea clearance have led to discordant findings. The aim of this study was to determine the relationship between the mean values of repeated instantaneous determinations of ID throughout a dialysis session ((m)ID), obtained using a single-step inlet dialysate conductivity profile, and the mean values of urea clearance corrected for access recirculation (K(eu1)), total recirculation (access plus cardiopulmonary recirculation, K(eu2)), and the entire postdialysis urea rebound (K(wb)).

Mini-peritoneal equilibration test: A simple and fast method to assess free water and small solute transport across the peritoneal membrane.

Background: Loss of ultrafiltration (UF) of peritoneal membrane is one of the most important causes of peritoneal dialysis failure. UF is determined by osmotic forces acting mainly across small pores (UFSP) and ultrasmall pores or free water transport. At present, only semiquantitative estimates or complicated computer simulations are available to assess free water transport.

What are we expecting to learn from the MPO study?

High-flux membranes represented a major improvement in dialysis technique, but evidences supporting their clinical superiority over conventional low-flux dialysis are still inconclusive. Although several studies, most of which were observational, showed an association between high-flux dialysis and lower morbidity and mortality, the Hemodialysis (HEMO) study, the first large-scale randomized clinical trial specifically aimed at testing the effect of membrane permeability on patients' outcome, failed to demonstrate a statistical significant benefit of high-flux membranes on all-cause mortality. Although disappointing, these results should however be interpreted in light of some important limitations of the HEMO study, first of all the inclusion of both incident and prevalent hemodialysis patients, the exclusion of sicker patients and the allowance of dialyzer reuse.

Long-term outcome in hemodialysis: morbidity and mortality.

Despite technical and pharmacological improvements achieved over the past years, long-term prognosis of patients undergoing chronic hemodialysis is still rather poor. Cardiovascular disease is the leading cause of both morbidity and mortality in these patients, mostly because of their severely compromised cardiovascular conditions already at the time of starting hemodialysis. A proper management of factors involved in the development of cardiovascular abnormalities is therefore a basic pre-requisite for improving their clinical outcome.

Ionic dialysance allows an adequate estimate of urea distribution volume in hemodialysis patients.

Background: An adequate estimation of urea distribution volume (V) in hemodialysis patients is useful to monitor protein nutrition. Direct dialysis quantification (DDQ) is the gold standard for determining V, but it is impractical for routine use because it requires equilibrated postdialysis plasma water urea concentration. The single pool variable volume urea kinetic model (SPVV-UKM), recommended as a standard by Kidney Disease Outcomes Quality Initiative (K/DOQI), does not need a delayed postdialysis blood sample but it requires a correct estimate of dialyser urea clearance.

Sodium removal and sodium concentration during peritoneal dialysis: effects of three methods of sodium measurement.

Background: Sodium removal (NaR) may have a major impact on the survival of peritoneal dialysis patients. The dialysate/plasma sodium concentration ratio (D/P(Na)) is an indirect index of transcellular water transport by aquaporin channels, and thus of ultrafiltration. Sodium concentration can be assessed by means of flame photometry (F), and direct (D-ISE) or indirect ion-selective electrodes (I-ISE), but these methods have different properties.

Convection versus diffusion in dialysis: an Italian prospective multicentre study.

The concept of dialysis adequacy has to be widened to include medium size and large molecule removal in addition to urea kinetics. The HEMO study found a non-significant trend toward a beneficial effect on mortality of high-flux dialysis compared with low-flux dialysis. In that study, the beneficial effect of convection could have been attenuated by the fact that 'internal filtration' in high-flux haemodialysis (HD) is lower than that expected by convection in haemofiltration (HF) or haemodiafiltration (HDF).

Sodium removal during pre-dilution haemofiltration.

Background: Cardiovascular instability still affects a large percentage of uraemic patients undergoing extracorporeal substitutive treatments. Post-dilution haemofiltration has been reported to be a method for improving cardiovascular stability; however, the limited removal of small molecular weight solutes together with the need for high blood flow from the fistula greatly restrict the use of this treatment. To increase the solute clearances and to partially resolve the necessity for high blood flow, the replacement solution, in a quantity about double that used in post-dilution mode, can be administered in pre-dilution mode.