Are Present Fat Emulsions Appropriate?

Proceedings From FDA/A.S.P.E.N. Public Workshop: Clinical Trial Design for Intravenous Fat Emulsion Products, October 29, 2013

The development of intravenous fat emulsion (IVFE) is the culmination of physiological, biochemical, nutritional, and medical scientific advancements. IVFEs have the ability to deliver critical nutritional substrates to the patient. Recent literature purports that they may also play roles in modulation of immune functionality and pulmonary physiology, but data supporting these potential benefits are limited. While soybean-based IVFEs have comprised the dominant fat in U.S. markets, a number of other novel IVFEs may prove to optimize the care of children and adults in both hospitalized and home settings. The October 2013 U.S. Food and Drug Administration (FDA)/American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) Public Workshop brought together scientists, researchers, and clinical experts to present updated clinical perspectives of IVFEs, including historical development, current state of usage throughout the world, and considerations for the regulatory approval of new IVFEs in the United States.

Effects of an omega-3 fatty acid-enriched lipid emulsion on eicosanoid synthesis in acute respiratory distress syndrome (ARDS): A prospective, randomized, double-blind, parallel group study

Background

The use of lipid emulsions has been associated with changes in lung function and gas exchange which may be mediated by biologically active metabolites derived from arachidonic acid. The type and quantity of the lipid emulsions used could modulate this response, which is mediated by the eicosanoids. This study investigates the use of omega-3 fatty acid-enriched lipid emulsions in ARDS patients and their effects on eicosanoid values.

Methods

Prospective, randomized, double-blind, parallel group study carried out at the Intensive Medicine Department of Vall d'Hebron University Hospital (Barcelona-Spain). We studied 16 consecutive patients with ARDS and intolerance to enteral nutrition (14 men; age: 58 ± 13 years; APACHE II score 17.8 ± 2.3; Lung Injury Score: 3.1 ± 0.5; baseline PaO₂/FiO₂ ratio: 149 ± 40). Patients were randomized into two groups: Group A (n = 8) received the study emulsion Lipoplus^® 20%, B. Braun Medical (50% MCT, 40% LCT, 10% fish oil (FO)); Group B (n = 8) received the control emulsion Intralipid^® Fresenius Kabi (100% LCT). Lipid emulsions were administered for 12 h at a dose of 0.12 g/kg/h. We measured LTB₄, TXB₂, and 6-keto prostaglandin F_1α values at baseline [immediately before the administration of the lipid emulsions (T-0)], at the end of the administration (T-12) and 24 hours after the beginning of the infusion (T 24) in arterial and mixed venous blood samples.

Results

In group A (FO) LTB₄, TXB₂, 6-keto prostaglandin F_1α levels fell during omega-3 administration (T12). After discontinuation (T24), levels of inflammatory markers (both systemic and pulmonary) behaved erratically. In group B (LCT) all systemic and pulmonary mediators increased during lipid administration and returned to baseline levels after discontinuation, but the differences did not reach statistical significance. There was a clear interaction between the treatment in group A (fish oil) and changes in LTB₄ over time.

Conclusions

Infusion of lipids enriched with omega-3 fatty acids produces significant short- term changes in eicosanoid values, which may be accompanied by an immunomodulatory effect.

Trial registration

ISRCTN63673813.

Gas exchange and pulmonary haemodynamic responses to fat emulsions in acute respiratory distress syndrome

OBJECTIVE

To investigate the gas exchange and pulmonary haemodynamic responses to two different intravenous fat emulsions in patients with acute respiratory distress syndrome (ARDS).

DESIGN

Prospective, randomized, double-blind, placebo-controlled study.

SETTING

Intensive care unit in a university-affiliated hospital.

PATIENTS

21 patients with ARDS [mean age, 57 +/- 3 (SEM) years; Acute Physiology and Chronic Health Evaluation II, 20 +/- 3; Murray's score, 2.85 +/- 0.12] consecutively admitted.

INTERVENTIONS

Patients were assigned to three groups (n = 7 each): group A (LCT) received long-chain triglycerides (20% LCT), group B (MCT/LCT), medium-chain triglycerides/long-chain triglycerides (20% MCT/LCT: 50/50) and group C placebo (0.9% sodium chloride, NaCl). The infusion was always given at the rate of 2 mg/kg min over a total period of 12 h, with a volume infusion of 500 ml in each group.

MEASUREMENTS

Data were collected before, immediately after and 12 h after infusion ceased. Pulmonary and systemic haemodynamic and gas exchange variables were measured at each time point. Serum triglyceride cholesterol, and non-esterified fatty acids levels were measured.

RESULTS

During LCT infusion, cardiac output, oxygen consumption and oxygen delivery increased (all p < 0.05), whereas pulmonary haemodynamics, arterial oxygen tension, mixed venous partial pressure of oxygen and venous admixture ratio remained essentially unaltered. No changes were observed following MCT/LCT infusion.

CONCLUSIONS

The administration of LCT emulsion given at a slow rate did not alter arterial oxygenation because of the beneficial effect of a high cardiac output, hence offsetting the detrimental effect of increased O2 consumption.