Nutrition in Acute Renal Failure

Adequate nutritional support is necessary to maintain protein stores and to correct pre-existing or disease-related deficits in lean body mass. The objectives for nutritional support for patients with acute renal failure (ARF) are not much different from those with other catabolic conditions. The principles of nutritional support for ARF, however, differ from those for patients with chronic renal failure (CRF), because diets or infusions that satisfy minimal requirements in CRF are not necessarily sufficient for patients with ARF. In patients with ARF modern nutritional therapy must include a tailored regimen designed to provide substrate requirements with various degrees of stress and hypercatabolism. If nutrition is provided to a patient with ARF the composition of the dietary program must be specifically designed because there are complex metabolic abnormalities that affect not only water, electrolyte, and acid-base-balance but also carbohydrate, lipid, and protein and amino acid utilization. In patients with ARF the main determinants of nutrient requirements (and outcome) are not renal dysfunction per se but the degree of hypercatabolism caused by the disease associated with ARF, the nutritional state, and the type and frequency of dialysis therapy. Pre-existing or hospital-acquired malnutrition has been identified as an important contributor to the persisting high mortality in critically ill persons. Thus, with modern nutritional support requirements must be met for all nutrients necessary for preservation of lean body mass, immunocompetence, and wound healing for a patient who has acquired ARF—in may instances among other complications. At the same time the specific metabolic alterations and demands in ARF and the impaired excretory renal function must be respected to limit uremic toxicity. In this chapter the multiple metabolic alterations associated with ARF are reviewed, methods for estimating nutrient requirements are discussed and, current concepts for the type and composition of nutritional programs are summarized. This information is relevant for designing nutritional support in an individual patient with ARF. Wilfred Druml