Long- and medium-chain triglycerides during parenteral nutrition in critically ill patients

Due to their special metabolic pathway, medium-chain triglycerides (MCT) have been claimed to be oxidized more extensively, compared with long-chain triglycerides (LCT), when administered as a parenteral nutritional support. This enhanced lipid oxidation rate of MCT emulsions could be particularly disclosed in hyperglycemic and hyperinsulinemic conditions. In an attempt to further elucidate this question, we measured substrate oxidation rates in critically ill patients liable to experience such metabolic conditions, that is to say postoperative patients after esophageal resection receiving 1.5 times their measured energy expenditure (n = 12) or after liver transplantation (n = 8). These patients received either LCT or MCT-LCT emulsions. The metabolic measurements were performed simultaneously by two methods, namely indirect calorimetry and isotopic methods based on natural abundance of nutrients. Although both groups of patients were hyperglycemic and hyperinsulinemic, the measured carbohydrate and lipid oxidation rates were not different with whatever type of lipid was administered. The MCT-LCT emulsions did not offer clear-cut advantages over LCT emulsions in critically ill patients when lipid energetic fate was considered.