Intradialytic Nutrition and Hemodialysis Prescriptions: A Personalized Stepwise Approach

Abstract

Dialysis and nutrition are two sides of the same coin-dialysis depurates metabolic waste that is typically produced by food intake. Hence, dietetic restrictions are commonly imposed in order to limit potassium and phosphate and avoid fluid overload. Conversely, malnutrition is a major challenge and, albeit to differing degrees, all nutritional markers are associated with survival. Dialysis-related malnutrition has a multifactorial origin related to uremic syndrome and comorbidities but also to dialysis treatment. Both an insufficient dialysis dose and excessive removal are contributing factors. It is thus not surprising that dialysis alone, without proper nutritional management, often fails to be effective in combatting malnutrition. While composite indexes can be used to identify patients with poor prognosis, none is fully satisfactory, and the definitions of malnutrition and protein energy wasting are still controversial. Furthermore, most nutritional markers and interventions were assessed in hemodialysis patients, while hemodiafiltration and peritoneal dialysis have been less extensively studied. The significant loss of albumin in these two dialysis modalities makes it extremely difficult to interpret common markers and scores. Despite these problems, hemodialysis sessions represent a valuable opportunity to monitor nutritional status and prescribe nutritional interventions, and several approaches have been tried. In this concept paper, we review the current evidence on intradialytic nutrition and propose an algorithm for adapting nutritional interventions to individual patients.

Keywords: Kt/V; MIS index; albumin; comorbidity; dialysis efficiency; elderly; hemodiafiltration; hemodialysis; malnutrition.

Figure A1

Tailored approach to intradialytic oral nutrition. A multiple choice menu for dialysis patients, allowing a selection of combination of energy or protein dense food.

Figure 1

Diffuse vascular calcifications in a patient with more than 30 years of follow-up on dialysis and after kidney transplantation. Arrows show eggshell calcifications of the iliac axes; scattered calcifications are visible in all other districts.

Figure 2

An example of sarcopenic obesity in a chronic hemodialysis patient affected by multiple myeloma. Arrows show poor quality, muscle tissue enrobed by well-developed adiposity.

Figure 3

A ladder, stepwise approach to interdialytic nutrition. In the first steps of the ladder, when nutritional markers are still normal, healthy food is advised to maintain nutritional status. Oral complements are needed when appetite is low and when energy and protein dense food may help restoring the nutritional balance. Intradialytic i.v. nutrition is an option in phases in which oral alimentation is low but the metabolic machine is not shut off, as witnessed by normal pre-albumin levels. Albumin may be needed when the low prealbumin levels suggest a very limited anabolic potential, not simply due to the lack of substrates, but usually linked to inflammation of acute diseases.