Fatty acid composition of platelet membrane lipids after administration oftwo different fat emulsions in critically ill patients

Objective: To determine the effects on platelet membrane fatty acid composi tion following administration of two different fat emulsions. Design: Prospective, randomized, double-blind study. Setting: Intensive care unit in a university-affiliated hospital. Patients: 12 adult critically ill patients in need of total parenteral nutr ition. Interventions:Patients were treated with total parenteral nutrition (TPN) f or 7 days, receiving for fat intake either a long-chain triglyceride (20 % LCT) emulsion (group 1, n = 6) or a medium-chain triglyceride-LCT (20 % MCT /LCT) emulsion (group 2, n = 6). Measurements and results: Highperformance liquid chromatography of membrane fatty acids was carried out before and after 7 days of TPN. In the LCT gro up, an increase in C18:2n-6 and a decrease in caprylic acid and docosahexae noic acid, which resulted in a decreased ratio of n-3/n-6 fatty acid conten t, was observed. In the MCT/LCT group, a reduced percentage of palmitoleic acid and arachidonic acid was shown. Conclusions: The observed changes in fatty acid composition are in agreemen t with the lipid composition of the fat emulsions used. Because the C18:2n- 6/C18:3n-3 ratio in both emulsions is close (approximately 9.0), the observ ed changes in the fatty acid composition of platelets may not be relevant f or platelet function.