Endogenous caloric sources and nitrogen balance: regulation in postoperative patients.

Twenty-three postoperative patients were divided into three groups to evaluate the peripheral vein administration of solutions containing glucose, amino acids, or glucose and amino acids. Serum insulin, glucose, and nitrogen balances were monitored in each patient. Serum insulin concentrations rose on the first postoperative day in all three groups, then fell to near preoperative levels by the third day after surgery. Negative nitrogen balance was most pronounced in patients recieving glucose only. Patients receiving only amino acids had a reduction in nitrogen balance, but some protein catabolism was present. The mean nitrogen balance in patients who received a combination of these solutions was positive on days one and two after surgery and slightly negative on the third postoperative day. These changes were not significantly better than the amino acid group. However, the combination group had 12 to 21 days of positive balance, as compared to seven of 20 days in the amino acid group. Since starvation adaptation accurs gradually, it is concluded that the simplest and safest way to reduce protein catabolism in the immediate postoperative period is by the peripheral intravenous administration of both glucose and amino acids.