Nitrogen-sparing effect of different feeding regimes in patients after operation

In patients recovering from surgery, water, electrolytes, protein and calories all produce significant nitrogen sparing whether given by i.v. or intraduodenal routes. The nitrogen-sparing effect of protein and calories is greater when given to these patients via the gastrointestinal tract, and nitrogen equilibrium is approached when nutrients are supplied in amounts that satisfy theoretical requirements. I.v. regimes do not achieve nitrogen equilibrium, even when amino acids and calories are supplied in amounts that exceed theoretical requirements.