id Injection) depends on daily proteinrequirements and on the patient's metabolic and clinical response. The determination of nitrogen balanceand accurate daily body weights, corrected for fluid balance, are probably the best means of assessingindividual protein requirements.
While Recommended Dietary Allowances of protein are approximately 0.8 g/kg of body weight for ahealthy adult and 1.4 to 2.2 g/kg for healthy growing infants and pediatric patients. It must be recognizedthat protein as well as caloric requirements in traumatized or malnourished patients may be substantiallyincreased. Daily amino acid doses of approximately 1.5 g/kg of body weight for adults and 2 to 3 g/kgof body weight for infants with adequate calories are generally sufficient to satisfy protein needs andpromote positive nitrogen balance. Higher doses may be required in severely catabolic states. Suchhigher doses, especially in infants, must be accompanied by frequent laboratory eva luation. Fat emulsionmay be supplied to help meet energy requirements.
Fat emulsion coadministration should be considered when prolonged (more than 5 days) parenteralnutrition is required in order to prevent essential fatty acid deficiency (E.F.A.D.). Serum lipids shouldbe monitored for evidence of E.F.A.D. in patients maintained on fat free TPN.
For protein sparing in well-nourished patients not receiving significant additional calories, amino aciddosages of 1.0 to 1.7 g/kg/day significantly reduce nitrogen losses and spare body protein. If rises inBUN exceed 20 mg% in 48 hours, amino acid infusion should be discontinued or rate of administration
reduced.
The provision of sufficient intracellular electrolytes, principally potassium, magnesium, and phosphate,is also required for optimum utilization of amino acids. Approximately 60–180 mEq of potassium, 10–30 mEq of magnesium, and 20–80 mEq of phosphate per day appear necessary to achieve optimummetabolic response. In addition, sufficient quantities of the major extracellular electrolytes (sodium,calcium, and chloride) must be given. In patients with hyperchloremic or other metabolic acidoses,sodium and potassium may be added as the acetate or lactate salts to provide bicarbonate precursor. Theelectrolyte content of 10% FreAmine® III (Amino Acid Injection) must be considered when calculatingdaily electrolyte intake. Serum electrolytes, including magnesium and phosphorus, should be monitored
frequently.
If a patient's nutritional intake is primarily parenteral, vitamins, especially the water soluble vitamins, and trace elements should also be provided.
Central Venous Nutrition
For severely catabolic, depleted patients or those requiring long-term total parenteral nutrition, centralvenous nutrition should be considered. Calorie-to-nitrogen ratios of at least 100 to 150 nonproteincalories per gram of nitrogen have been recommended to achieve positive nitrogen balance in suchpatients. These ratios are easily and conveniently attained with the use of concentrated dextrosesolutions, supplemented if desired with parenteral fat emulsion.
Total parenteral nutrition may be started with infusates containing lower concentrations of dextrose;dextrose content may be gradually increased to estimated caloric needs as the patient's glucosetolerance increases.
In adults, strongly hypertonic mixtures of amino acids and dextrose may be safely administere |
