Inflammatory responses to intravenous fish oil, soybean oil and medium-chain triglyceride fat emulsions in young children before and after open-heart surgery

The consequences of critical illness are profound, causing dysregulation of nutrients, metabolic and immunologic abnormalities. Fatty acids have profound effects on metabolism and immune function. The nutritional management of critically ill infants is a challenging task and the use of total parenteral nutrition becomes necessary to match their metabolic needs both pre- and post-operatively and to decrease catabolism. Intravenous lipid emulsions are a vital part of total parenteral nutrition and have the potential to impact inflammation, infection, long-chain polyunsaturated fatty acid profile and clinical outcomes. Pro-inflammatory cytokines can be suppressed by 20:5n-3 (EPA) and 22:6n-3 (DHA) fatty acids. Infusing intravenous emulsions containing predominantly n-6 fatty acid (53% n-6, 8% n-3) may exacerbate inflammation. Surgery and infection lead to excessive inflammation, resulting in systemic inflammatory response syndrome and multi-organ dysfunction.Inflammation was assessed by measuring plasma cytokine production and infection was evaluated using sepsis indicators and procalcitonin levels. Fatty acid content of plasma phospholipids, plasma free fatty acids and leukotriene 4 levels were analyzed during study time points. Clinical outcomes including hospital outcome data, calorie intake and routine hospital laboratory results were also compared between intravenous dietary treatments. This thesis demonstrates that providing a lipid emulsion containing long-chain n-3 polyunsaturated fatty acids decreases the production of a key inflammatory cytokine in infants undergoing heart surgery. Novel findings include decreased lymphocyte concentrations, procalcitonin concentrations and tumor necrosis factor-alpha during sepsis when given the fish oil containing emulsion. Of interest was that plasma arachidonic acid levels did not differ between groups. It is concluded that EPA and DHA fatty acids may provide a useful therapy for treating the hyperinflammatory state of these infants and may improve clinical outcomes. The association between total length of stay associated with the higher tumor necrosis factor-alpha concentrations in the control group may warrant change in critical care feeding practice.The objective of this thesis was to determine whether incidence of sepsis and degree of inflammatory response is improved in critically ill infants after cardiopulmonary bypass for open-heart surgery when given a combination medium-chain triglyceride oil, soybean oil, and fish oil emulsion versus a soybean oil emulsion. There have been adverse immunological effects reported using standard soybean oil-based lipid emulsions in adult critical care literature. These adverse immunologic effects have not been examined in infants.