Parenteral nutrition in the septic patient: nitrogen balance, limiting plasma amino acids, and calorie to nitrogen ratios

Abstract

A series of eight septic patients was provided varying levels of beef fibrin protein hydrolysate by central vein in the presence of adequate calories for evaluation of nitrogen retention under septic conditions. The mean nitrogen intake to achieve nitrogen equilibrium was 240 mg/kg of body wt per day. This represents a 40% increase over that required to produce nitrogen equilibrium in normal adults. The mean caloric intake of these patients was 43.3 kcal/kg of body wt per day. The calorie to nitrogen ratio based on the above intake was calculated to be 180:1. In order to utilize effectively calorie to nitrogen ratios in the nutritional care of patients, it is suggested that ratios be standardized using daily total coloric expenditures. Correcting the mean measured resting calorie expenditures of these patients for minimal daily activity, a caloric to nitrogen ratio of 138:1 was obtained. The plasma amino acid ratios in these septic patients confirm the finding that valine and phenylalnine are limiting amino acids in a beef fibrin hydrolysate at infusion levels below 240 mg of N/kg of body wt per day. Analysis of the urinary excretion of total nitrogen, urea, and amino acids in two patients suggests that 30 to 50% of the infused peptides of a beef fibrin hydrolysate are lost in the urine in these septic patients.