Supplemented low-protein diet and once-weekly hemodialysis

Protection of Residual Renal Function and Nutritional Treatment: First Step Strategy for Reduction of Uremic Toxins in End-Stage Kidney Disease Patients

The retention of uremic toxins and their pathological effects occurs in the advanced phases of chronic kidney disease (CKD), mainly in stage 5, when the implementation of conventional thrice-weekly hemodialysis is the prevalent and life-saving treatment. However, the start of hemodialysis is associated with both an acceleration of the loss of residual kidney function (RKF) and the shift to an increased intake of proteins, which are precursors of uremic toxins. In this phase, hemodialysis treatment is the only way to remove toxins from the body, but it can be largely inefficient in the case of high molecular weight and/or protein-bound molecules. Instead, even very low levels of RKF are crucial for uremic toxins excretion, which in most cases are protein-derived waste products generated by the intestinal microbiota. Protection of RKF can be obtained even in patients with end-stage kidney disease (ESKD) by a gradual and soft shift to kidney replacement therapy (KRT), for example by combining a once-a-week hemodialysis program with a low or very low-protein diet on the extra-dialysis days. This approach could represent a tailored strategy aimed at limiting the retention of both inorganic and organic toxins. In this paper, we discuss the combination of upstream (i.e., reduced production) and downstream (i.e., increased removal) strategies to reduce the concentration of uremic toxins in patients with ESKD during the transition phase from pure conservative management to full hemodialysis treatment.

Green nephrology and eco-dialysis: a position statement by the Italian Society of Nephrology

High-technology medicine saves lives and produces waste; this is the case of dialysis. The increasing amounts of waste products can be biologically dangerous in different ways: some represent a direct infectious or toxic danger for other living creatures (potentially contaminated or hazardous waste), while others are harmful for the planet (plastic and non-recycled waste). With the aim of increasing awareness, proposing joint actions and coordinating industrial and social interactions, the Italian Society of Nephrology is presenting this position statement on ways in which the environmental impact of caring for patients with kidney diseases can be reduced. Due to the particular relevance in waste management of dialysis, which produces up to 2 kg of potentially contaminated waste per session and about the same weight of potentially recyclable materials, together with technological waste (dialysis machines), and involves high water and electricity consumption, the position statement mainly focuses on dialysis management, identifying ten first affordable actions: (1) reducing the burden of dialysis (whenever possible adopting an intent to delay strategy, with wide use of incremental schedules); (2) limiting drugs and favouring "natural" medicine focussing on lifestyle and diet; (3) encouraging the reuse of "household" hospital material; (4) recycling paper and glass; (5) recycling non-contaminated plastic; (6) reducing water consumption; (7) reducing energy consumption; (8) introducing environmental-impact criteria in checklists for evaluating dialysis machines and supplies; (9) encouraging well-planned triage of contaminated and non-contaminated materials; (10) demanding planet-friendly approaches in the building of new facilities.

Pro: The rationale for dietary therapy for patients with advanced chronic kidney disease

Dietary treatment offers many benefits to patients with advanced chronic kidney disease (CKD) who are approaching the need for renal replacement therapy. A large number of these benefits are independent of whether diets slow the rate of progression of CKD. These diets are low in protein and many minerals, and provide adequate energy for the CKD patient. The diets can reduce accumulation of potentially toxic metabolic products derived from protein and amino acid degradation, maintain a healthier balance of body water, sodium, potassium, phosphorus, calcium and other minerals, and prevent or improve protein-energy wasting. Such diets may enable patients to safely delay the onset of chronic dialysis therapy or kidney transplantation. Dietary therapy may also augment the effectiveness of infrequent or incremental dialysis by maintaining healthier metabolic and clinical status and may enable some end-stage renal disease patients to avoid the need for temporary placement of hemodialysis catheters while their arterial venous fistulae or grafts mature. The anxiety that many advanced CKD patients commonly experience with regard to starting dialysis may incentivize them to accept and adhere to dietary therapy.

Precision Medicine for Nutritional Management in End-Stage Kidney Disease and Transition to Dialysis

Chronic kidney disease (CKD) is a global public health burden. Dialysis is not only costly but may not be readily available in developing countries. Even in highly developed nations, many patients may prefer to defer or avoid dialysis. Thus, alternative options to dialysis therapy or to complement dialysis are needed urgently and are important objectives in CKD management that could have huge clinical and economic implications globally. The role of nutritional therapy as a strategy to slow CKD progression and uremia was discussed as early as the late 19th and early 20th century, but was only seriously explored in the 1970s. There is a revival of interest recently owing to encouraging data as well as the increase of precision medicine with an emphasis on a personalized approach to CKD management. Although part of the explanation for the inconclusive data may relate to variations in study design and dietary prescription, diversity in genetic make-up, variations in the non-nutritional management of CKD, intra-individual variations in responses to dietary and nondietary treatment, psychosocial factors, and dietary compliance issues, these all may contribute to the heterogeneous data and responses. This brings in the evolving concept of precision medicine, in which disease management should be tailored and individualized according not only to clinical manifestations but also to the genetic make-up and biologic responses to therapy, which may vary depending on genetic composition. Precision nutrition management also should take into account patient demographics, social, psychological, education, and compliance factors, which all may influence the therapeutic needs and responses to the nutritional therapy prescribed. In this review, we provide a novel concept of precision medicine in nutritional management in end-stage kidney disease with a transition to dialysis and propose how this may be the way forward for nutritional therapy in the CKD population.

Nutritional treatment of advanced CKD: twenty consensus statements

The Italian nephrology has a long tradition and experience in the field of dietetic-nutritional therapy (DNT), which is an important component in the conservative management of the patient suffering from a chronic kidney disease, which precedes and integrates the pharmacological therapies. The objectives of DNT include the maintenance of an optimal nutritional status, the prevention and/or correction of signs, symptoms and complications of chronic renal failure and, possibly, the delay in starting of dialysis. The DNT includes modulation of protein intake, adequacy of caloric intake, control of sodium and potassium intake, and reduction of phosphorus intake. For all dietary-nutritional therapies, and in particular those aimed at the patient with chronic renal failure, the problem of patient adherence to the dietetic-nutritional scheme is a key element for the success and safety of the DNT and it can be favored by an interdisciplinary and multi-professional approach of information, education, dietary prescription and follow-up. This consensus document, which defines twenty essential points of the nutritional approach to patients with advanced chronic renal failure, has been written, discussed and shared by the Italian nephrologists together with representatives of dietitians (ANDID) and patients (ANED).

The strange case of Mr. H. Starting dialysis at 90 years of age: clinical choices impact on ethical decisions

Background

Starting dialysis at an advanced age is a clinical challenge and an ethical dilemma. The advantages of starting dialysis at “extreme” ages are questionable as high dialysis-related morbidity induces a reflection on the cost- benefit ratio of this demanding and expensive treatment in a person that has a short life expectancy. Where clinical advantages are doubtful, ethical analysis can help us reach decisions and find adapted solutions.

Case presentation

Mr. H is a ninety-year-old patient with end-stage kidney disease that is no longer manageable with conservative care, in spite of optimal nutritional management, good blood pressure control and strict clinical and metabolic evaluations; dialysis is the next step, but its morbidity is challenging. The case is analysed according to principlism (beneficence, non-maleficence, justice and respect for autonomy).

In the setting of care, dialysis is available without restriction; therefore the principle of justice only partially applied, in the absence of restraints on health-care expenditure. The final decision on whether or not to start dialysis rested with Mr. H (respect for autonomy). However, his choice depended on the balance between beneficence and non-maleficence. The advantages of dialysis in restoring metabolic equilibrium were clear, and the expected negative effects of dialysis were therefore decisive. Mr. H has a contraindication to peritoneal dialysis (severe arthritis impairing self-performance) and felt performing it with nursing help would be intrusive. Post dialysis fatigue, poor tolerance, hypotension and intrusiveness in daily life of haemodialysis patients are closely linked to the classic thrice-weekly, four-hour schedule. A personalized incremental dialysis approach, starting with one session per week, adapting the timing to the patient’s daily life, can limit side effects and “dialysis shock”.

Conclusions

An individualized approach to complex decisions such as dialysis start can alter the delicate benefit/side-effect balance, ultimately affecting the patient’s choice, and points to a narrative, tailor-made approach as an alternative to therapeutic nihilism, in very old and fragile patients.

Current Uses of Dietary Therapy for Patients with Far-Advanced CKD

For several decades, inquiry concerning dietary therapy for nondialyzed patients with CKD has focused mainly on its capability to retard progression of CKD. However, several studies published in recent years indicate that, independent of whether diet can delay progression of CKD, well designed low-protein diets may provide a number of benefits for people with advanced CKD who are close to requiring or actually in need of RRT. Dietary therapy may both maintain good nutritional status and safely delay the need for chronic dialysis in such patients, offering the possibility of improving quality of life and reducing health care costs. With the growing interest in incremental dialysis, dietary therapy may enable lower doses of dialysis to be safely and effectively used, even as GFR continues to decrease. Such combinations of dietary and incremental dialysis therapy might slow the rate of loss of residual GFR, possibly reduce mortality in patients with advanced CKD, improve quality of life, and also, reduce health care costs. The amount of evidence that supports these possibilities is limited, and more well designed, randomized clinical trials are clearly indicated.

Nutritional Issues with Incremental Dialysis: The Role of Low-Protein Diets

A gentle start of dialysis is a welcome possibility for both patients and physicians. Incident dialysis patients often maintain residual kidney function (RKF) for a considerable period of time; the start of dialysis is often driven mainly by uremic symptoms. Recently, the combination of a low-protein diet, along with a less-frequent dialysis schedule, has regained interest as an alternative option in selected and motivated patients. In addition, there is renewed interest in a low-protein diet in patients with moderate to advanced chronic kidney disease (CKD). Dietary regimens have additional objectives now: obtaining better control of phosphate and potassium levels; preventing or reducing metabolic acidosis, protein catabolism, and malnutrition; and reducing uremic symptoms. In the eighties and early nineties, data from uncontrolled studies showed that combining a very low-protein diet with once weekly hemodialysis was a feasible approach. However, these diets were very demanding with poor patient compliance and had a high risk of smoldering malnutrition. However, recent experience has shown that the new protein-free foods have better palatability and nutritional properties; this has increased adherence to dietary prescriptions. Dietary regimens are now tailored to the patient's needs and habits. A multidisciplinary approach is considered crucial for updating medical needs and dietary prescriptions, ensuring adherence to the combined program, and avoiding the development of malnutrition and inadequate dialysis. Monitoring RKF is another key factor for the success of the program due to the importance of optimal timing of the transition to twice-weekly regimens and, eventually, thrice-weekly hemodialysis.

Incremental Hemodialysis, Residual Kidney Function, and Mortality Risk in Incident Dialysis Patients: A Cohort Study

BACKGROUND

Maintenance hemodialysis is typically prescribed thrice weekly irrespective of a patient's residual kidney function (RKF). We hypothesized that a less frequent schedule at hemodialysis therapy initiation is associated with greater preservation of RKF without compromising survival among patients with substantial RKF.

STUDY DESIGN

A longitudinal cohort.

SETTING & PARTICIPANTS

23,645 patients who initiated maintenance hemodialysis therapy in a large dialysis organization in the United States (January 2007 to December 2010), had available RKF data during the first 91 days (or quarter) of dialysis, and survived the first year.

PREDICTOR

Incremental (routine twice weekly for >6 continuous weeks during the first 91 days upon transition to dialysis) versus conventional (thrice weekly) hemodialysis regimens during the same time.

OUTCOMES

Changes in renal urea clearance and urine volume during 1 year after the first quarter and survival after the first year.

RESULTS

Among 23,645 included patients, 51% had substantial renal urea clearance (≥3.0mL/min/1.73m(2)) at baseline. Compared with 8,068 patients with conventional hemodialysis regimens matched based on baseline renal urea clearance, urine volume, age, sex, diabetes, and central venous catheter use, 351 patients with incremental regimens exhibited 16% (95% CI, 5%-28%) and 15% (95% CI, 2%-30%) more preserved renal urea clearance and urine volume at the second quarter, respectively, which persisted across the following quarters. Incremental regimens showed higher mortality risk in patients with inadequate baseline renal urea clearance (≤3.0mL/min/1.73m(2); HR, 1.61; 95% CI, 1.07-2.44), but not in those with higher baseline renal urea clearance (HR, 0.99; 95% CI, 0.76-1.28). Results were similar in a subgroup defined by baseline urine volume of 600mL/d.

LIMITATIONS

Potential selection bias and wide CIs.

CONCLUSIONS

Among incident hemodialysis patients with substantial RKF, incremental hemodialysis may be a safe treatment regimen and is associated with greater preservation of RKF, whereas higher mortality is observed after the first year of dialysis in those with the lowest RKF. Clinical trials are needed to examine the safety and effectiveness of twice-weekly hemodialysis.

Low-protein diets for chronic kidney disease patients: the Italian experience

BACKGROUND

Nutritional treatment has always represented a major feature of CKD management. Over the decades, the use of nutritional treatment in CKD patients has been marked by several goals. The first of these include the attainment of metabolic and fluid control together with the prevention and correction of signs, symptoms and complications of advanced CKD. The aim of this first stage is the prevention of malnutrition and a delay in the commencement of dialysis. Subsequently, nutritional manipulations have also been applied in association with other therapeutic interventions in an attempt to control several cardiovascular risk factors associated with CKD and to improve the patient's overall outcome. Over time and in reference to multiple aims, the modalities of nutritional treatment have been focused not only on protein intake but also on other nutrients.

DISCUSSION

This paper describes the pathophysiological basis and rationale of nutritional treatment in CKD and also provides a report on extensive experience in the field of renal diets in Italy, with special attention given to approaches in clinical practice and management. Italian nephrologists have a longstanding tradition in implementing low protein diets in the treatment of CKD patients, with the principle objective of alleviating uremic symptoms, improving nutritional status and also a possibility of slowing down the progression of CKD or delaying the start of dialysis. A renewed interest in this field is based on the aim of implementing a wider nutritional therapy other than only reducing the protein intake, paying careful attention to factors such as energy intake, the quality of proteins and phosphate and sodium intakes, making today's low-protein diet program much more ambitious than previous. The motivation was the reduction in progression of renal insufficiency through reduction of proteinuria, a better control of blood pressure values and also through correction of metabolic acidosis. One major goal of the flexible and innovative Italian approach to the low-protein diet in CKD patients is the improvement of patient adherence, a crucial factor in the successful implementation of a low-protein diet program.

Dietary Management of Incremental Transition to Dialysis Therapy: Once-Weekly Hemodialysis Combined With Low-Protein Diet

Initiation of thrice-weekly hemodialysis often results in a rapid loss of residual kidney function (RKF) including reduction in urine output. Preserving RKF longer is associated with better outcomes including greater survival in dialysis patients. An alternative approach aimed at preserving RKF is an incremental transition with less frequent hemodialysis sessions at the beginning with gradual increase in hemodialysis frequency over months. In addition to favorable clinical and economic implications, an incremental transition would also enhance a less stressful adaptation of the patient to dialysis therapy. The current guidelines provide only limited recommendations for incremental hemodialysis approach, whereas the potential role of nutritional management of newly transitioned hemodialysis patients is largely overlooked. We have reviewed previous reports and case studies of once-weekly hemodialysis treatment combined with low-protein, low-phosphorus, and normal-to-high-energy diet especially for nondialysis days, whereas on dialysis days, high protein can be provided. Such an adaptive dietary regimen may elicit more favorable outcomes including better preserved RKF, lower β2-microglobulin levels, improved phosphorus control, and lower doses of erythropoiesis-stimulating agents. Clinical and nutritional status and RKF should be closely monitored throughout the transition to once and then twice-weekly regimen and eventually thrice-weekly hemodialysis. Further studies are needed to verify the long-term safety and implications of this approach to dialysis transition.

Progressive Hemodialysis: Is It The Future?

Progressive hemodialysis is based on the simple idea of adjusting its dose according to residual renal function (RRF). The progressive, infrequent paradigm is slowly gaining a foothold among nephrologists, despite a lot of skepticism in the scientific world. Given the importance of RRF preservation in conservative therapy, it seems a contradiction to ignore the contribution of RRF when patients initiate hemodialysis (HD), especially when it is routinely considered with peritoneal dialysis. While a three-times-weekly HD regimen is broadly considered the standard starting regimen for new patients, twice-weekly HD has been used in selected patients and is currently a common practice in South-East Asia. Small studies indicate that a once-weekly HD regimen may be a viable starting option as well. Progressive hemodialysis still requires validation, yet it is promising. We share the belief that a randomized clinical trial to investigate progressive hemodialysis is much needed, but we also strongly recommend including a once-weekly HD starting dose as part of any such investigation.

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. Adequate sodium (Na) and water removal is critical for preventing intra- and interdialytic hypotension and pulmonary edema. Avoiding both hyper- and hypokalaemia prevents life-threatening cardiac arrhythmias. Optimal calcium (Ca) and magnesium (Mg) dialysate concentrations may protect the cardiovascular system and the bones, preventing extraskeletal calcifications, severe secondary hyperparathyroidism and adynamic bone disease. Adequate bicarbonate concentration [HCO₃⁻] maintains a stable pH in the body fluids for appropriate protein and membrane functioning and also protects the bones. An adequate dialysate glucose concentration prevents severe hyperglycaemia and life-threating hypoglycaemia, which can lead to severe cardiovascular complications and a worsening of diabetic comorbidities.

The incremental treatment of ESRD: a low-protein diet combined with weekly hemodialysis may be beneficial for selected patients

BACKGROUND

Infrequent dialysis, namely once-a-week session combined with very low-protein, low-phosphorus diet supplemented with ketoacids was reported as a useful treatment schedule for ESRD patients with markedly reduced residual renal function but preserved urine output. This study reports our findings from the application of a weekly dialysis schedule plus less severe protein restriction (standard low-protein low-phosphorus diet) in stage 5 CKD patients with consistent dietary discipline.

METHODS

This is a multicenter, prospective controlled study, including 68 incident CKD patients followed in a pre-dialysis clinic with Glomerular Filtration Rate 5 to 10 ml/min/1.73/ m2 who became unstable on the only medical treatment. They were offered to begin a Combined Diet Dialysis Program (CDDP) or a standard thrice-a-week hemodialysis (THD): 38 patients joined the CDDP, whereas 30 patients chose THD. Patients were studied at baseline, 6 and 12 months; hospitalization and survival rate were followed-up for 24 months.

RESULTS

Volume output and residual renal function were maintained in the CDDP Group while those features dropped quickly in THD Group. Throughout the study, CDDP patients had a lower erythropoietin resistance index, lower β2 microglobulin levels and lower need for cinacalcet of phosphate binders than THD, and stable parameters of nutritional status. At 24 month follow-up, 39.4% of patients were still on CDDP; survival rates were 94.7% and 86.8% for CDDP and THD patients, respectively, but hospitalization rate was much higher in THD than in CDDP patients. The cost per patient per year resulted significantly lower in CDDP than in THD Group.

CONCLUSIONS

This study shows that a CDDP served to protect the residual renal function, to maintain urine volume output and to preserve a good nutritional status. CDDP also blunted the rapid β2 microglobulin increase and resulted in better control of anemia and calcium-phosphate abnormalities. CDDP was also associated with a lower hospitalization rate and reduced need of erythropoietin, as well as of drugs used for treatment of calcium-phosphate abnormalities, thus leading to a significant cost-saving. We concluded that in selected ESRD patients with preserved urine output attitude to protein restriction, CDDP may be a beneficial choice for an incremental hemodialysis program.

Infrequent dialysis: a new paradigm for hemodialysis initiation

Nearly a half-century ago, the thrice-weekly hemodialysis schedule was empirically established as a means to provide an adequate dialysis dose while also treating the greatest number of end-stage renal disease (ESRD) patients using limited resources. Landmark trials of hemodialysis adequacy have historically been anchored to thrice-weekly regimens, but a recent randomized controlled trial demonstrated that frequent hemodialysis (six times per week) confers cardiovascular and survival benefits. Based on these collective data and experience, clinical practice guidelines advise against a less than thrice-weekly treatment schedule in patients without residual renal function, yet provide limited guidance on the optimal treatment frequency when substantial native kidney function is present. Thus, during the transition from Stage 5 chronic kidney disease to ESRD, the current paradigm is to initiate hemodialysis on a "full-dose" thrice-weekly regimen even among patients with substantial residual renal function. However, emerging data suggest that frequent hemodialysis accelerates residual renal function decline, and infrequent regimens may provide better preservation of native kidney function. Given the high mortality rates during the first 6 months of hemodialysis and the survival benefits of preserved native kidney function, initiation with twice-weekly treatment schedules ("infrequent hemodialysis") with an incremental increase in frequency over time may provide an opportunity to optimize patient survival. This review outlines the clinical benefits of post-hemodialysis residual renal function, studies of twice-weekly treatment regimens, and the potential risks and benefits of infrequent hemodialysis.

Ethical issues in the elderly with renal disease

Despite the many technical advances in medical care and dialysis delivery, mortality and morbidity remain high in patients with end-stage renal disease. This is particularly true in older patients, who often have a great number of coexisting diseases. In this population, life expectancy and quality of life may be rather poor, raising a number of ethical issues about the decision of starting start or withdrawing renal replacement therapy. Unfortunately, clear behavior guidelines on these critical issues are still insufficient. Reasons for not starting dialysis include old age, neurologic impairment, end-stage organ failure other than the kidneys, metastatic cancer, multiple comorbidities, and patient or family refusal. Similar reasons often underlie dialysis withdrawal of dialysis. Often these difficult decisions are left to care givers and family members or surrogates, since only a minority of patients with severe medical conditions discuss end-of-life care before becoming mentally impaired. The final shared decision should be the result of weighing beneficence (to maximise maximize good) with non-maleficence (to not cause harm); in the presence of severe medical conditions and/or mental impairment, dialysis may represent a prolongation of death rather than life.

Nutritional support in chronic renal failure: systematic review

BACKGROUND AND AIMS

The purpose of this systematic review was to locate and assess in patients with chronic renal disease the quality of scientific evidence to establish graded recommendations based on the efficacy and effectiveness of nutritional support.

METHODS

Computerized and online versions of MEDLINE (from 1989 through March 1999) and EMBASE (from 1988 through January 1999) were consulted. The Cochrane Library and the online Healthstar (from 1975) databases were also searched for clinical trials. A total of 593 studies were assessed. Following methodological review (primary reviewer), only 45 studies reviewed met criteria for selection and were analyzed by a group of experts (secondary reviewer). A final consensus was reached between the co-ordinators, experts and methodologists.

RESULTS AND CONCLUSIONS

Low and very low-protein diets associated with specific enteral supplements are indicated in most patients with chronic renal disease and in patients with incipient diabetic nephropathy to slow progression of disease and to improve their overall status, contributing to improved survival (grade A recommendation). The use of protein-restricted diets in diabetic nephropathy is only indicated in type I diabetes mellitus (grade A recommendation). An improvement in nutritional parameters was found when specific diets were given in chronic renal disease (grade C recommendation).

Effect of a new model of hemodialysis potassium removal on the control of ventricular arrhythmias

The primary aim of this multicenter, prospective, randomized cross-over study was to clarify whether a new model of hemodialysis (HD) potassium (K) removal using a decreasing intra-HD dialysate K concentration and a constant plasma-dialysate K gradient (treatment B) is capable of reducing the arrhythmogenic effect of standard HD, which has a constant dialysate K concentration and decreasing plasma-dialysate K gradient (treatment A). The secondary aim was to verify whether this new model is clinically safe. In treatment B, the initial dialysate K concentration had to be 1.5 mEq/liter less than the plasma K concentration, and exponentially decrease to 2.5 mEq/liter at the end of HD. Forty-two chronic HD patients with an increase in premature ventricular complexes (PVC) during dialysis were enrolled from 18 participating centers, and randomly assigned to either sequence 1 (ABA) or sequence 2 (BAB). A pool of 333 of 378 expected ECG Holter recordings were checked for signal quality; 269 (71%) from 36 patients (86%) had a satisfactory signal quality and 108 were selected for analysis (1 per patient per period). There was a difference in the natural logarithm of the increase in PVC/hr and PVC couplets/hr during HD between treatments A and B (1.70 +/- 1.59 vs. 1.09 +/- 1.76 and 0.94 +/- 0.86 vs. 0.64 +/- 1.01, a reduction of 36% and 32%, P = 0.011 and 0.047, respectively) without any carry over effect (P = 0.61 and 0.24, respectively). The fact that this decrease of one third is due to a lower plasma-dialysate K gradient is supported by the observation that it was more evident during the first than the last two hours of HD (a reduction in the natural logarithm of the increase in PVC/hr and PVC couplets/hr of 60% and 60%, P 0.002 and 0.009, vs. 26% and 17%, P = 0.098 and 0.332, respectively): the initial plasma-dialysate K gradient was 2.3 times lower during treatment B than during treatment A, without adversely affecting pre-HD plasma K levels. These results could have a considerably clinical impact not only because of the possibility of physiologically decreasing the arrhythmogenic effect of HD, but also because this effect can be considered a "marker" of the electrophysiological derangement induced by the administration of standard HD three times a week for years ("electric disequilibrium syndrome").