[Total parenteral nutrition in critical patients. The metabolic-nutritional aspects and effects on immune function of 2 different isocaloric-isonitrogenous regimens].

The aim of this investigation was to compare, in a randomized short-term study the effects on some parameters evaluating lipid metabolism, nutritional status and immune function of two different patients. Particularly, the influence of the intravenous (i.v.) infusion of a fat emulsion on above-mentioned parameters was evaluated. The two regimens (G and GL) were isocaloric (about 30 kcal.kg-1.d-1 non protein energy) and isonitrogenous (about 0.27 g.kg-1.d-1 nitrogen); the only difference was the source of non-protein calories administered. Regimen G consisted of glucose-based TPN (100% of non-protein energy as glucose) whereas, in regimen GL (glucose-lipid-based TPN), the 55% of non-protein caloric supply was given as glucose and 45% as lipids. 9 of the patients were randomly assigned to receive regimen GL (group GL) and 8 to receive regimen G (group G). TPN was delivered through a central vein catheter for 8 days; during this period no hepatic or metabolic complications have been observed. Clinical and laboratory tests were performed at day 0 (enrollment), at day 4 (after 4 days of TPN) and at day 8 (at the end of TPN). Both regimens of TPN were able to induce an improvement of the nutritional status and serum prealbumin (TBPA) significantly increased in all patients (p < 0.05). The results of the immune measurements showed that no significant change in immune function during the administration of either regimen occurred. However, in group GL, we observed a slight, non significant change in the percentage numbers of T-cells subpopulations that resulted in a decrease in the ratio of helper to suppressor T-cells (H:S). Serum lipids and lipoprotein profile didn't change significantly in group GL. On the contrary, in group G, we observed a significant decrease in serum concentrations of HDL cholesterol (p < 0.05), LDL cholesterol and apo A1 (p < 0.01) while total cholesterol remained unchanged; a non significant rise in serum triglyceride also occurred, These results show that the two regimens had a similar impact on nutritional status in both groups. The i.v. infusion of the fat emulsion didn't alter lipid profile and was not associated with an impairment of some aspects of the immune function. In conclusion, our results confirm that fat emulsions represent an important component of i.v. nutritional support regimens and should continue to be used when and where indicated in short-term TPN. However, long-term effects of i.v. infusion of fat emulsions on the immune systems should be further investigated, in a more substantial number of patients.