Dialysis dose as a determinant of adequacy

Choices in hemodialysis therapies: variants, personalized therapy and application of evidence-based medicine

The extent of removal of the uremic toxins in hemodialysis (HD) therapies depends primarily on the dialysis membrane characteristics and the solute transport mechanisms involved. While designation of ‘flux’ of membranes as well toxicity of compounds that need to be targeted for removal remain unresolved issues, the relative role, efficiency and utilization of solute removal principles to optimize HD treatment are better delineated. Through the combination and intensity of diffusive and convective removal forces, levels of concentrations of a broad spectrum of uremic toxins can be lowered significantly and successfully. Extended clinical experience as well as data from several clinical trials attest to the benefits of convection-based HD treatment modalities. However, the mode of delivery of HD can further enhance the effectiveness of therapies. Other than treatment time, frequency and location that offer clinical benefits and increase patient well-being, treatment- and patient-specific criteria may be tailored for the therapy delivered: electrolytic composition, dialysate buffer and concentration and choice of anticoagulating agent are crucial for dialysis tolerance and efficacy. Evidence-based medicine (EBM) relies on three tenets, i.e. clinical expertise (i.e. doctor), patient-centered values (i.e. patient) and relevant scientific evidence (i.e. science), that have deviated from their initial aim and summarized to scientific evidence, leading to tyranny of randomized controlled trials. One must recognize that practice patterns as shown by Dialysis Outcomes and Practice Patterns Study and personalization of HD care are the main driving force for improving outcomes. Based on a combination of the three pillars of EBM, and particularly on bedside patient–clinician interaction, we summarize what we have learned over the last 6 decades in terms of best practices to improve outcomes in HD patients. Management of initiation of dialysis, vascular access, preservation of kidney function, selection of biocompatible dialysers and use of dialysis fluids of high microbiological purity to restrict inflammation are just some of the approaches where clinical experience is vital in the absence of definitive scientific evidence. Further, HD adequacy needs to be considered as a broad and multitarget approach covering not just the dose of dialysis provided, but meeting individual patient needs (e.g. fluid volume, acid–base, blood pressure, bone disease metabolism control) through regular assessment—and adjustment—of a series of indicators of treatment efficiency. Finally, in whichever way new technologies (i.e. artificial intelligence, connected health) are embraced in the future to improve the delivery of dialysis, the human dimension of the patient–doctor interaction is irreplaceable. Kidney medicine should remain ‘an art’ and will never be just ‘a science’.

Adequacy of Hemodialysis and Its Associated Factors among Patients Undergoing Chronic Hemodialysis in Dar es Salaam, Tanzania

The worldwide prevalence of maintenance hemodialysis continues to rise. An adequate delivery of hemodialysis dose as measured by Kt/V or urea reduction ratio is a crucial determinant of clinical outcome for chronic hemodialysis patients. The aim of this study was to assess the adequacy of hemodialysis and its associated factors among patients undergoing chronic hemodialysis in Dar es Salaam. This was a cross-sectional study done on patients undergoing chronic hemodialysis in four dialysis centers in Dar es Salaam. Sociodemographic information and treatment characteristics were collected. Urea reduction rate and single-pool Kt/V were calculated to determine the adequacy of hemodialysis. The data were analyzed and any associated factors for inadequate hemodialysis were determined using a chi-square test and a logistic regression analysis. A total of 143 patients participated in the study. Males represented 65.7% of the study population. The mean age (±SD) was 51.7 ± 1.2 years. Only 34.3% (based on urea reduction ratio (URR)) and 40.6% (based on Kt/V) of patients received adequate hemodialysis. The univariate analysis showed that males were more likely to have inadequate dialysis (65.6% versus 48.0%, p=0.048 based on Kt/V). Patients using hemodialyzers with dialyzer surface area less than 1.4 m² received significantly less hemodialysis dose than those with more than 1.4 m² (69.0% versus 41.2%, p=0.02, by URR) (62.7% versus 35.3%, p=0.03, by Kt/V criteria). Patients who had hemoglobin <10 g/dl received significantly inadequate hemodialysis dose as compared to patients with hemoglobin ≥10 g/dl by Kt/V criteria (69.8% versus 51.3%, p=0.03). None of the factors acquired significance in the multivariate analysis. The proportion of patients receiving an adequate hemodialysis dose is low (34.3% based on URR and 40.6% based on Kt/V). Male gender, dialyzer surface area of <1.4 m², and hemoglobin level of <10 g/dl were associated with an inadequate delivered dose of hemodialysis in the univariate analysis but not in the multivariate analysis. This study can increase awareness about the importance of measuring hemodialysis adequacy and giving the correct hemodialysis dose to achieve the intended benefit.

[Physical principles of renal replacement therapy applied to end stage renal disease patients]

"Hemodialysis" is the generic term that refers to all forms of renal replacement therapy (RRT) able to restore periodically the "internal milieu" composition in end stage renal disease patients (ESRD). RRT includes several modalities (hemodialysis, hemofiltration, hemodiafiltration) that induce basic physical principles (diffusion, convection, adsorption) via an exchange module (dialyser) and an electrolytic exchange solution (dialysis fluid). The cleansing property of the RRT depends on different factors: the treatment modality itself, the uremic toxin considered, patient's characteristic and the operational conditions (duration of treatment, session frequency, blood and dialysate flow rates). Solute instantaneous clearances reflect the dialyser's performances used in optimal conditions but not necessarily the body clearance. The effective solute body clearance is more difficult to assess in clinical practice since it includes some variables such as the treatment duration, the biological complexity of internal milieu and the variability of the patient/dialysis system interaction. The "dialysis adequacy" concept that governs the treatment efficacy in ESRD patients could not be reduced to the urea Kt/V ratio. It must integrate a selection of pertinent clinical and biological markers covering the complete spectrum of uremic abnormalities. Adequate knowledge of those basic physical principles that control the solute exchange in hemodialysis patient is highly recommended to any nephrologist who looks forward to improve treatment efficacy and reduce mortality in ESRD patients.

A wearable haemodialysis device for patients with end-stage renal failure: a pilot study

BACKGROUND

More frequent haemodialysis can improve both survival and quality of life of patients with chronic kidney disease. However, there is little capacity in the UK to allow patients to have more frequent haemodialysis treatments in hospital and satellite haemodialysis units. New means of delivering haemodialysis are therefore required. Our aim was to assess the safety and efficiency of a wearable haemodialysis device.

METHODS

Eight patients with end-stage kidney failure (five men, three women, mean age 51.7 [SD 13.8] years) who were established on regular haemodialysis were fitted with a wearable haemodialysis device for 4-8 h. Patients were given unfractionated heparin for anticoagulation, as they would be for standard haemodialysis.

FINDINGS

There were no important cardiovascular changes and no adverse changes in serum electrolytes or acid-base balance. There was no evidence of clinically significant haemolysis in any patient. Mean blood flow was 58.6 (SD 11.7) mL/min, with a dialysate flow of 47.1 (7.8) mL/min. The mean plasma urea clearance rate was 22.7 (5.2) mL/min and the mean plasma creatinine clearance rate was 20.7 (4.8) mL/min. Clotting of the vascular access occurred in two patients when the dose of heparin was decreased and the partial thromboplastin time returned towards the normal reference range in both of these patients. The fistula needle became dislodged in one patient, but safety mechanisms prevented blood loss, the needle was replaced, and treatment continued.

INTERPRETATION

This wearable haemodialysis device shows promising safety and efficacy results, although further studies will be necessary to confirm these results.

Intradialytic parenteral nutrition does not improve survival in malnourished hemodialysis patients: a 2-year multicenter, prospective, randomized study

Although intradialytic parenteral nutrition (IDPN) is a method used widely to combat protein-calorie malnutrition in hemodialysis patients, its effect on survival has not been thoroughly studied. We conducted a prospective, randomized trial in which 186 malnourished hemodialysis patients received oral nutritional supplements with or without 1 year of IDPN. IDPN did not improve 2-year mortality (primary end point), hospitalization rate, Karnofsky score, body mass index, or laboratory markers of nutritional status. Instead, both groups demonstrated improvement in body mass index and the nutritional parameters serum albumin and prealbumin (P < 0.05). Multivariate analysis showed that an increase in prealbumin of >30 mg/L within 3 months, a marker of nutritional improvement, independently predicted a 54% decrease in 2-year mortality, as well as reduced hospitalizations and improved general well-being as measured by the Karnofsky score. Therefore, although we found no definite advantage of adding IDPN to oral nutritional supplementation, this is the first prospective study demonstrating that an improvement in prealbumin during nutritional therapy is associated with a decrease in morbidity and mortality in malnourished hemodialysis patients.

Comment atteindre et maintenir les recommandations K/DOQITM sur le métabolisme phosphocalcique chez les patients dialysés: une stratégie efficace

INTRODUCTION

Recent publications have indicated that alterations in bone and mineral metabolism are known to participate to a high mortality rate in patients undergoing haemodialysis. A new therapeutic strategy is progressively undertaken in the dialysis unit over a 36 months period covering years 2002 to 2004.

METHODS

This new strategy includes the prescription of non-calcium, non-aluminium phosphate binder, sevelamer hydrochloride, an increase in vitamin D analogues prescription and a moderation in calcium carbonate administration. Sixty patients participated to the entire study and are evaluated three times a year on the four K/DOQI parameters. Other indicators such as haemoglobin, bicarbonate, total cholesterol and HDL cholesterol levels were studied.

RESULTS

At the beginning of the study, 7% of the patients achieved the four K/DOQI parameters. This proportion seemed identical to those observed in the major studies. But progressively with the new therapeutic strategy 13%, then 21%, and at the end of the study 35% reached the four criteria. Therapeutic calcium intakes decreased from 100 g per patient/month to 28 g per patient-month. Prescription of vitamin D analogues increased from 3.3 microg per patient-month to 18.3 microg per patient/month. At the end of the study 60% of the patients received sevelamer hydrochloride at the mean dosage of 4800 mg per day. Haemoglobin remains stable. Bicarbonate level decreased due to a minor prescription in calcium carbonate. Under statins the ratio total cholesterol/HDL cholesterol decreased to 3.3.

CONCLUSION

A modification in the therapeutic strategy offer to patients undergoing haemodialysis, the possibility to achieve the K/DOQI recommendations with the hope to obtain a beneficial effect on patient outcomes.