HEMODYNAMIC, RESPIRATORY, AND METABOLIC EFFECTS OF MEDIUM-CHAIN TRIGLYCERIDE-ENRICHED LIPID EMULSIONS FOLLOWING VALVULAR HEART-SURGERY

Study: A lipid emulsion containing 10 percent medium-chain triglycerid es (MCT) and 10 percent long-chain triglycerides (LCT) was infused at a rate of 1 ml/kg/h (3.3 mg/kg/min) for 2 h, in 12 patients (2 males, 10 females; mean age, 54+/-3 (SEM) years; range, 34 to 67 years) 24 h after open-heart surgery (mitral valve replacement). Methods: Hemodyna mic factors (pulmonary and radial artery indwelling catheters), oxygen and carbon dioxide partial pressures, oxygen saturation, oxygen deliv ery and consumption, and intrapulmonary shunt fraction were obtained b efore, during, and after lipid infusion (for 2 h), at 30-s intervals, along with some metabolic indexes (triglycerides, free fatty acids, gl ucose, insulin, lactate, acetoacetate). Results: No statistically sign ificant changes in heart rate, cardiac index, systemic and pulmonary p ressures and resistances, central venous and pulmonary capillary press ures, or arterial oxygen partial pressure were observed during infusio n. Arterial carbon dioxide partial pressure values were constantly red uced throughout and after the end of lipid infusion, as compared with baseline values, while oxygen consumption was increased significantly without any change in oxygen delivery. No adverse effects on intrapulm onary shunt fraction were observed. Statistically significant increase s of triglycerides, free fatty acids, acetoacetate and insulin (peak v alues at end of the lipid infusion) were found in comparison with base line values. Plasma glucose increased significantly during lipid infus ion and remained higher than baseline values until the end of the stud y. Lactate levels were unchanged, except for a slight decrease at the end of the study, without any derangement of acid-base equilibrium. Ne ither arrhythmias nor adverse clinical reactions were observed as a co nsequence of lipid infusion. Conclusion: Fat emulsions containing both MCT and LCT, when given at 3.3 mg/kg/min for 120 min following valvul ar heart surgery, do not exert negative cardiopulmonary effects, and c ould represent a source of rapidly metabolized substrates.