New horizons (Baltimore, Md.)
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Studies over the past three decades have documented the protein-anabolic effects of human growth hormone (GH) administration in malnourished or critically ill patients. The availability of recombinant GH has facilitated clinical investigation on the metabolic and clinical effects of this peptide in ICU settings. These studies demonstrate that GH improves nutrient utilization efficiency in critically ill patients. ⋯ However, little data have been published on functional or clinical outcome variables in other groups of catabolic patients treated with GH. Administration of growth factors in combination with specialized nutrition represents a novel strategy that may improve outcomes in critically ill patients. Additional clinical studies are needed to further define the safety, functional benefits, cost-effectiveness, and clinical utility of GH use in catabolic patients.
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It is clear that amino acid-based nutritional support beneficially affects nitrogen balance. Less clear is the optimal composition of amino acids for nutritional support of the catabolic patient. ⋯ We discuss the concept of conditionally indispensable amino acids and review the requirements for histidine, serine, arginine, taurine, cysteine, tyrosine, and glutamine. The use of dipeptides for parenteral support of critically ill patients is reviewed and proposed changes in amino acid content for the catabolic patient are advanced.
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Nutritional support of the seriously ill patient has evolved with time and reflects new developments in the field of critical care. Current information suggests that optimal nutritional support can be provided by supplying at least 80% of energy requirements with at least 70% of the energy given as carbohydrate and the remaining 30% or less administered as fat (with > or = 3% of energy requirements as essential fatty acids). The caloric load may be reduced to 50% of requirements if growth factors (e.g., growth hormone) are utilized and the patient has adequate fat stores. ⋯ Nutrients should be administered early in the catabolic course, especially glucose, sodium, potassium, vitamins, and minerals. Over time (approximately 7 days) amino acids should be added and approximately 50% of caloric support should be provided. Finally, full nutritional support should be provided (by 7 to 10 days) if the catabolic course is expected to continue.
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Overfeeding occurs when the administration of calories and/or specific substrate exceeds the requirements to maintain metabolic homeostasis. These requirements are substantially altered during periods of injury-induced acute metabolic stress. Excess nutritional delivery during this period can further increase the metabolic demands of acute injury and place an added burden on the lungs and liver. ⋯ In these acutely-stressed infants, measured energy expenditure constitutes the total energy requirement, and caloric delivery in excess of this amount should be avoided until metabolic stress parameters indicate resolution of the acute injury state. Enteral delivery should be used in preference to parenteral feeding. Even if total caloric delivery cannot be achieved enterally, the provision of a small amount of the total energy budget via the enteral route is generally possible and is likely advantageous.(ABSTRACT TRUNCATED AT 250 WORDS)
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Dietary manipulation may influence outcome after infection and injury by altering production of inflammatory mediators and disease activity. Restricted nutrient intake may have beneficial effects on life-span, development of degenerative disease, autoimmune processes, renal injury, susceptibility to infection, and survival rate after infection. ⋯ The optimal calorie/protein intake during different phases of critical illness remains to be established. However, a short period of restricted intake may be beneficial.