Parenteral nutrition in septic patients: effect of increasing nitrogen intake

Metabolic effects of increasing nitrogen intake during total parenteral nutrition (TPN) were studied in nine septic patients. The patients were given 5% dextrose (D5W) for 1 d. For the next 6 d they received total parenteral nutrition (TPN), at 1.35 times resting energy expenditure (REE), containing either 191 or 366 mg N/(kg.d) Non-protein calories were divided equally between glucose and lipid emulsion. Three patients were studied on both diets (n = 6 for each diet). On the high- but not the low-N diet were significant increases in protein oxidation, blood urea N, O2 consumption, and CO2 production. TPN normalized most plasma amino acid levels but intramuscular amino acids remained unchanged. Transient positive N balance occurred during days 1-3 on the high- but not the low-N intake; on days 5-6 N balance did not differ significantly from zero on either diet and the improvement (165 mg N/[kg.d]) was the same for both diets.