Infusion time for fish oil-containing parenteral emulsions in surgery: A study on ω-3 fatty acid dynamics in rats.

OBJECTIVES: The aim of this study was to contribute to the design of specialized parenteral nutrition protocols in surgery by evaluating the dynamics of polyunsaturated fatty acid (PUFA) concentrations in different body pools after the infusion of fish oil-containing lipid emulsion (FOLE) in rats that had undergone surgical central venous catheterization (CVC). METHODS: After 5-d adaptation in metabolic cages, 78 male Lewis rats (300-450 g) fed a standard diet were sacrificed (baseline control) or had only CVC (surgical control) or also received a 72-h infusion of a parenteral lipid emulsion with or without fish oil. The catheterized animals were sacrificed 0 (T0), 2 (T2), 6 (T6), and 12 h (T12) after the infusion ended. Gas chromatography was used to determine the concentrations of eicosapentaenoic (EPA), docosahexaenoic (DHA), and arachidonic (ARA) acids and the ω-3 to ω-6 ratio in plasma, liver, and blood leukocytes. Kruskal-Wallis and Wilcoxon tests were applied to plasma and liver data and descriptive analysis to leukocyte data. RESULTS: Plasma, liver, and leukocytes exhibited almost undetectable EPA and DHA and detectable ARA concentrations at baseline. Immediately after FOLE infusion (T0), these PUFAs changed in all pools, resulting in a higher ratio of ω-3 to ω-6 compared with rats with no FOLE infusion (P < 0.05). All these changes decreased over time, with residual effects remaining until T6 in plasma, T12 in liver, and only until T2 in leukocytes. CONCLUSION: Data from this study suggest that ω-3 PUFAs are cleared early after the end of FOLE infusion, mainly in leukocytes. This should be considered when FOLEs are applied for immunomodulatory purposes in surgery.

Is There an Advantage in Enriching Parenteral Lipid Emulsions Containing Fatty Acids From Fish Oil With Medium-Chain Triglycerides? A Study on Body Pool Concentrations of ω-3 Fatty Acids in Lewis Rats.

BACKGROUND: The addition of medium-chain triglycerides (MCTs) into parenteral lipid emulsions rich in fatty acids from fish oil (FOLEs) has been shown to improve their clearance and extrahepatic uptake. We assessed whether this effect could favor the leukocyte uptake of ω-3 polyunsaturated fatty acids (PUFAs) for immunomodulatory purposes METHODS: Following 5-day adaptation in metabolic cages, 42 male Lewis rats fed with AIN-93M chow were killed (baseline control group [BC]) or submitted to central venous catheterization and distributed into (1) surgical control group without parenteral infusion (chow group), (2) test emulsion (MCT/LCT/FO) group with the parenteral infusion of a FOLE containing 40% MCT, and (3) control emulsion group (LCT/FO) with the parenteral infusion of an FOLE without MCT. The 2 FOLEs had similar ω-3 PUFA contents and ω-6/ω-3 PUFA ratios and were infused during 48 and 72 hours. Concentrations of ω-3 and ω-6 PUFAs in plasma, liver, and blood mononuclear and polymorphonuclear leukocytes were assessed by gas chromatography RESULTS: In both FOLE groups, leukocyte concentrations of ω-3 PUFAs peaked after 48 hours' infusion (vs BC). At this time point, plasma concentrations of ω-3 PUFAs were higher in MCT/LCT/FO group than in LCT/FO group and the opposite was found in the liver (P<.05), but no differences in PUFA concentrations were observed between these groups in leukocytes (P>.05) CONCLUSION: The ω-3 PUFAs provided by FOLEs rich in MCT were less incorporated by liver and remained more available for extrahepatic cell delivery, but this did not result in a clear benefit in increasing their incorporation by peripheral leukocytes.