Nutrition in Acute Renal Failure: A Reappraisal for the 1990s

Nutritional assessment and support during continuous renal replacement therapy

Malnutrition is highly prevalent in patients with acute kidney injury, especially in those receiving renal replacement therapy (RRT). For the assessment of nutritional status, a combination of screening tools, anthropometry, and laboratory parameters is recommended rather than a single test. To avoid underfeeding and overfeeding during RRT, energy expenditure should be measured by indirect calorimetry or calculated using predictive equations. Nitrogen balance should be periodically measured to assess the degree of catabolism and to evaluate protein intake. However, there is limited data for nutritional targets specifically for patients on RRT, such as protein intake. The composition of commercial solutions for continuous renal replacement therapy (CRRT) varies. CRRT itself can be associated with both, nutrient losses into the effluent fluid and caloric gain from dextrose, lactate, and citrate. The role of micronutrient supplementation, and potential use of micronutrient enriched CRRT solutions in this setting is unknown, too. This review provides an overview of existing knowledge and uncertainties related to nutritional aspects in patients on CRRT and emphasizes the need for more research in this area.

The Use of Parenteral Nutrition in a Severely Malnourished Hemodialysis Patient With Hypercalcemia

There is a high prevalence of protein-energy malnutrition (PEM) in chronic dialysis patients. Causes of PEM include the catabolic effects of hemodialysis treatments, acidemia associated with end-stage renal disease, common comorbid conditions, and uremia-induced anorexia. Morbidity and mortality increase with PEM. Before considering parenteral nutrition (PN) as a nutrition intervention in a maintenance dialysis patient, all other efforts to promote optimal nutrition need to be exhausted. The first step is careful evaluation of protein-energy status, followed by intensive nutrition counseling. If necessary, this is followed by oral nutrition supplementation, appetite stimulation, enteral tube feedings, and finally PN. Short-term parenteral nutrition (PN) became a crucial component of the management of a 38-year-old hemodialysis (HD) patient who endured serious complications after kidney transplant rejection. A profound and prolonged malnourished state followed her treatment for necrotizing pancreatitis. She had developed persistent hypercalcemia believed secondary to tertiary hyperparathyroidism (HPT) and immobilization. Later, she developed hungry bone syndrome (HBS) after parathyroidectomy (PTX). She also developed refeeding syndrome after initiation of PN. The patient's persistent, poorly understood hypercalcemia did not resolve even after PTX and removal of all other sources of vitamin D and calcium from her feedings, medications, and dialysis bath. The close communication of the inpatient and outpatient dialysis multidisciplinary teams became a key component to the successful outcome in this complex patient.

Dialysis modalities in the intensive care unit

Acute renal failure in the ICU is a clinically diverse entity. Consequently, the indications for initiation of dialysis therapy are varied. In general, the indications are solute control, volume control, or both. A variety of dialysis modalities are available; however, there is no consensus as to the optimal modality for any particular group of patients. A careful understanding of the particular benefits, limitations, and potential complications of each modality coupled with a thorough assessment of the individual patient's need formulate the basis for dialysis modality selection. In certain circumstances, the more conventional intermittent therapies are sufficient, whereas in other settings, CRRT techniques are advantageous. The impact of modality selection on outcome remains an area of significant controversy. Future studies in which more uniformity within specific subgroups of patients with ARF is sought may shed light on the optimal modality for a particular patient group. Newer therapies aimed at more optimal and more specific blood purification may prove promising in the management of complex critically ill patients with ARF and other comorbid conditions.

Nutrition assessment and support of organ transplant recipients

Timely nutrition assessment and intervention in organ transplant recipients may improve outcomes surrounding transplantation. A pretransplant nutrition assessment should include a variety of parameters including physical assessment, history, anthropometric measurements, and laboratory tests. Malnutrition compromises posttransplant survival; prolonged waiting times worsen outcomes when patients are already malnourished. Severe obesity may decrease graft function and survival in kidney transplant recipients. In the pretransplant phase, nutritional goals include optimization of nutritional status and treatment of nutrition-related symptoms induced by organ failure. Enteral tube feeding is indicated for patients with functional gastrointestinal tracts who are not eating adequately. Parenteral nutrition is rarely needed pretransplant except in cases of intestinal failure. When determining pretransplant nutrient requirements, nutritional status, weight, age, gender, metabolic state, stage and type of organ failure, malabsorption, induced losses, goals, and comorbid conditions must be considered. During the acute posttransplant phase, adequate nutrition is required to help prevent infection, promote wound healing, support metabolic demands, replenish lost stores, and perhaps mediate the immune response. Nutrient recommendations reflect posttransplant metabolic changes. The appropriateness of posttransplant nutrition support depends on the prevalence of malnutrition among patients with a specific type of organ failure and the benefits when nutrition support is given. Organ transplantation complications including rejection, infection, wound healing, renal insufficiency, hyperglycemia, and surgical complications require specific nutritional requirements and therapies. Many potential applications of nutrition in the pre- and posttransplant phases exist and require further study.