The effect on energy and nitrogen metabolism by continuous, bolus, or sequential infusion of a defined total parenteral nutrition formulation in patients after major surgical procedures.

BACKGROUND

The role of IV infusion kinetics to explain nutrition efficiency was investigated in patients after major surgical procedures.

METHODS

IV nutrition was provided as three different infusion kinetic regimens in a randomized fashion. All patients received nonprotein calories (100% of predicted preoperative REE, 60% D-glucose, 40% fat) and amino acid nitrogen (0.2 g N/d). Group A: Nutrition was provided by sequential infusion with combined fat and amino acids during daytime and glucose alone during nighttime ("sequential infusion"). Group B: Patients received 24-hour combined infusion with fat, amino acids, and glucose (all in one mixture) ("continuous infusion"). Group C: Nutrition was provided by bolus infusions during 1 hour followed by 2 hours without any infusion ("bolus infusion").

RESULTS

The daily energy balance was negative in all groups (-318 +/- 25 kcal/d, sequential infusion; -368 +/- 25 kcal/d continuous infusion; -292 +/- 20 kcal/d, bolus infusion). Significantly different excretion patterns of nitrogen in urine occurred among the groups despite an almost identical provision of nitrogen. Continuously infused patients retained nitrogen significantly better (-0.2 +/- 0.6 g/d) compared with sequentially (-3.4 +/- 1.0 g/d) and bolus-infused patients (-2.8 +/- 0.3 g/d) (p < .01), whereas their cumulative urinary glucose excretion was significantly larger. Continuously infused patients were in cumulative nitrogen balance during the entire postoperative period, whereas the other groups were in a significantly negative nitrogen balance. Urinary 3-methylhistidine excretion was similar in all groups.

CONCLUSIONS

The breakdown of muscle proteins was not sensitive to alterations in nutrient and substrate supply. Thus improved nitrogen retention reflected entirely improved synthesis. "All-in-one" IV nutrition with prolonged infusion periods is at present the most favorable regimen considering both the nutritional efficiency and its metabolic load on the organism after major surgery.