Effect of tracer and intravenous fat emulsion on the measurement of reticuloendothelial system function

State of the art review: Intravenous fat emulsions: Current applications, safety profile, and clinical implications

OBJECTIVE

To review the current state of the science regarding intravenous fat emulsions (IVFEs), with an emphasis on their safety profile.

DATA SOURCES

Articles were identified via a search of the MEDLINE database, including publications from 1979 to December 2009, using a search string that included the terms parenteral nutrition, lipid emulsion, fat emulsion, IVFE, safety, adverse effect, neonate intralipid, and terms describing a range of specific adverse events (AEs) such as pancreatitis.

STUDY SELECTION AND DATA EXTRACTION

We selected articles that allowed us to compare the results of clinical trials involving delivery of medications via IVFEs with the historical use and effects of IVFEs in parenteral nutrition, with an emphasis on AEs. We focused on 2 drugs in current use that are administered intravenously in lipid emulsions: propofol and clevidipine.

DATA SYNTHESIS

Clearance of the fat particles in IVFEs is mediated by the enzyme lipoprotein lipase. AEs are more likely if the rate or duration of IVFE administration exceeds the enzyme's clearance capacity. AEs are also more likely after administration of a 10% IVFE formulation than a 20% formulation, because the higher concentration of free phospholipid in the 10% formulation interferes with lipoprotein lipase activity. AEs can be reduced by administering IVFEs at a dosage < or = 2.5 g/kg/day and at a rate < or = 0.11 g/kg/h. The anesthetic agent propofol, which is formulated in a 10% IVFE, has been used clinically for 25 years. Typical AEs associated with propofol use include infection, high plasma triglyceride concentrations, and pancreatitis. Recent clinical trials involving clevidipine, which is formulated in a 20% IVFE, have demonstrated a low rate of lipid-related AEs.

CONCLUSIONS

The results of this review demonstrate that IVFEs are well tolerated when administered in accordance with guideline recommendations.

Lipid and lipid-free total parenteral nutrition: differential effects on macrophage phagocytosis in rats

Lipid emulsions provided with total parenteral nutrition (TPN) have been associated with mononuclear phagocytic system functional changes. The aim of the present investigation was to assess the influence of TPN with added lipid emulsions on macrophage (M phi) phagocytosis. Wistar rats (n = 70) with external jugular vein cannulation were randomized into seven groups. The rats received an oral diet or six different isocaloric (1.16 kcal/mL), isonitrogenous (1.5 g/mL), and isolipidic (30% non-protein calories) TPN regimens: (a) an oral diet with intravenous infusion of saline (OS); (b) non-lipid TPN (glucose); (c) TPN with 10% long chain triacylglycerol emulsions (LCT); (d) TPN with 90% LCT and 10% fish oil (FO) emulsion; (e) TPN with 50% LCT and 50% FO; (f) TPN with 10% lipid emulsion with 50% medium chain triacylglycerol (MCT) and 50% LCT; and (g) TPN with 45% MCT, 45% LCT, and 10% FO. After 96 h of TPN or saline infusion, colloidal carbon (Pelikan, Germany) was injected intravenously at 1.0 mL/kg body weight, and the rats were killed after 3 h. Liver, spleen, and lung were weighed and prepared by immunohistochemistry analyses with the HAM-56 anti-M phi antibody. Under light microscopy, the total M phi number (MT) and the colloidal carbon phagocytic M phi number (MP) were established, and the phagocytic index was calculated as MP/MT x 100. There were no statistical (P < 0.05) differences in liver, spleen, or lung weights among the seven groups in comparison with the OS group. Non-lipid TPN inhibited spleen and lung M phi phagocytosis when compared with the OS and lipid-TPN groups. Lipid TPN supplemented with fish oil emulsion increased total liver and lung M phi number and phagocytosis. These results indicate that TPN supplemented with fish oil increases M phi phagocytosis in rats.