Metabolic rate and nitrogen balance in patients receiving bolus intermittent total parenteral nutrition infusion.

The present study investigated whether infusion principles are significant factors that influence the nutritional efficiency of complete intravenous nutrition. For this purpose, three infusion modalities were evaluated in patients who underwent elective and uncomplicated cholecystectomy. The nutrition regimens were as follow: group 1, sequential infusion of fat plus amino acids at a constant rate over 12 hours during daytime followed by glucose infusion at a constant rate for 12 hours during nighttime; group 2, simultaneous infusion of all substrates at a constant rate over 24 hours; and group 3, simultaneous infusion of all substrates with bolus-based intermittent infusions during 60 minutes six times per day (24 hours). Nonprotein calories corresponded to 160% of the individually measured resting need and were provided as 60% carbohydrate and 40% fat. Nitrogen was provided as crystalline amino acids in solution at 0.2 g of nitrogen per kilogram per day. All patients were randomized into three comparable groups. Intermittent nutrition (group 3) was associated with a significantly higher thermic effect, which led to a significantly lower although still positive energy balance than either sequential nutrition (group 1) or constant nutrition (group 2). The mean daily nitrogen balance was, however, significantly improved in patients receiving intermittent nutrition, and this was accompanied by much higher plasma insulin levels as well as higher plasma amino acid concentrations. This study demonstrates that all substrates should be given simultaneously and that supplementation of intravenous nutrition in boluses, similar to meal feeding, gave the most pronounced protein accretion when compared with either sequential administration of total parenteral nutrition or administration of all admixtures with constant infusion over 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)