Agglutinate formation in serum samples mixed with intravenous fat emulsions

A novel fatty acid lipophilic index and risk of CHD in US men: the health professionals follow-up study

Few epidemiological studies have examined the association between an overall fatty acid (FA) profile and CHD risk. The aim of the present study was to examine a novel index that summarises individual FA levels based on FA affinity and fluidity in relation to CHD risk in men. In a prospective nested case–control study, FA in plasma and erythrocytes were measured in 459 CHD cases and 879 matched controls. Lipophilic index (LI) was computed by summing the products between FA levels and melting point of each FA to reflect the overall FA lipophilicity. Among controls, higher plasma LI was significantly correlated with adverse profiles of blood lipids, inflammatory markers and adiponectin. After multivariate adjustment for age, smoking, BMI and other CHD risk factors, plasma LI was significantly associated with an increased risk of CHD: the relative risk was 1·61 (95% CI 1·03, 2·53; P for trend¼0·04) comparing extreme quintiles. This association was attenuated to 1·21 (95% CI 0·48, 3·09; P for trend¼0·77) after adjusting for plasma levels of total trans-FA, long-chain n-3 FA and polyunsaturated:saturated fat ratio. Erythrocyte LI was not significantly associated with CHD risk. The present data indicate that a novel LI is associated with an adverse profile of cardiovascular risk markers and increased risk of CHD in men; its usefulness as a complement of individual FA in assessing disease risk needs to be elucidated in future studies.

Comparison of Methods for Intravenous Infusion of Fat Emulsion During Extracorporeal Membrane Oxygenation

STUDY OBJECTIVES

To characterize the effects of infusing fat emulsion during neonatal extracorporeal membrane oxygenation (ECMO) by comparing results from patients receiving fat emulsion through the ECMO circuit with those receiving fat emulsion through separate intravenous access. A second goal was to identify the optimal route for administration.

DESIGN

Prospective, randomized, open-label trial.

SETTING

Neonatal intensive care unit in a 106-bed quaternary care pediatric hospital.

SUBJECTS

Nine neonates receiving ECMO who required intravenous nutrition. Intervention. Patients received 1-3 g/kg/day of fat emulsion into either the ecmo circuit or separate intravenous access.

MEASUREMENTS AND MAIN RESULTS

The ECMO circuit and samples of blood were evaluated hourly for phase separation, layering out of the emulsion from blood, agglutination, and blood clots. After completion, the oxygenators were dissected and examined. Data were compared with an unpaired t test. The characteristics of the groups were similar, except for a higher mean weight in the ECMO circuit group (3.6 +/- 0.3 kg vs 2.8 +/- 0.4 kg, p=0.03). The mean +/- SD triglyceride level during the study was 87 +/- 79 mg/dl, with no significant difference between the two groups. Two patients in each group had elevated triglyceride levels. No cases of phase separation occurred. In the five patients who received fat emulsion into the ECMO circuit, three had layering out of the emulsion and agglutination, and all developed clots in the circuit despite adequate anticoagulation. Of the four patients in the intravenous-access group, one had layering and agglutination, and two had blood clots.

CONCLUSIONS

Although both methods were associated with layering out, agglutination, and clot formation, these effects occurred more frequently with administration into the ECMO circuit, particularly in areas of stasis. This may result in disruption of normal ECMO blood flow and impaired delivery of calories. Fat emulsion should therefore be administered through separate intravenous access during ECMO whenever possible.

Nutritional support of infants and children: supply and metabolism of lipids

The quantity and quality of dietary lipids and their metabolism are of major importance for the growth, body composition, development and long-term health of children, both in health and disease. Lipids are the major source of energy in early childhood and supply essential lipid-soluble vitamins and polyunsaturated fatty acids that are required in relatively high amounts during early growth. Lipids affect the composition of membrane structures, and modulate membrane functions as well as the functional development of the central nervous system. Some long-chain polyunsaturated fatty acids serve as precursors for bioactive lipid mediators, including prostaglandins, thromboxanes and leukotrienes, which are powerful regulators of numerous cell functions such as thrombocyte aggregation, inflammatory reactions and immune functions. Here we review some aspects of the biochemistry and physiology of lipids and their implications for lipoprotein metabolism, energy balance and the lipid supply during early childhood through the placenta, human milk, enteral diets and parenteral lipid emulsions.

Propofol and intralipid cause creaming of serum from critically ill patients

The aim of this in-vitro study was to investigate the incidence of propofol agglutination with serum from critically ill patients. Serum (400 microliters) from 58 critically ill patients and 30 healthy volunteers was incubated with 10 microliters of either propofol, Intralipid 10% or Intralipid 20%. Control incubations contained serum only. At 24 h, the serum was examined macroscopically and microscopically for agglutination. Agglutination was seen with Intralipid 20% in serum from all critically ill patients and 13.3% of volunteers. Serum from 91.4% of critically ill patients was agglutinated with Intralipid 10% and only 3.3% of the healthy volunteers. In comparison, propofol produced agglutination in 74.1% of critically ill patients and in none of the serum from healthy volunteers (p < 0.05 propofol versus Intralipid 10%, p < 0.0001 propofol versus Intralipid 20%). No correlation was seen between agglutination and age, sex, APACHE II score or plasma concentration of acute phase proteins. However, agglutination of propofol and Intralipid 10% was more frequent (p < 0.001) in serum from patients with pulmonary disease, than in patients with normal lungs. The clinical implications of these in-vitro findings are unclear and need further investigation.

[Intra-macrophage lipid particles collected by bronchoalveolar lavage: incidence and diagnostic value]

This study aimed to determine the incidence and diagnostic value of fat-laden alveolar macrophages obtained by bronchoalveolar lavage (BAL). In 128 patients, including 66 patients admitted for multiple trauma, 158 BAL were carried out. However, 41 BAL from 32 patients were excluded because of poor quality of samples (not enough macrophages, too many ciliated cells, or haemorrhage). All the patients were intubated and mechanically ventilated, having pulmonary infiltrates on the chest film. BAL samples were examined after staining with oil-red-O. They were considered to be positive when more than 5% of alveolar macrophages contained fat droplets. Among them 14 out of 47 patients (30%) without multiple trauma were positive; 7/14 had never been given any intravenous lipid infusion, and 5/14 had aspiration pneumonia (as opposed to 3/32 patients with negative BAL). Further 27 patients out of the 49 (55%) with multiple trauma were positive. Among them 10/49 had clinical evidence of fat embolism, however, only 7/10 had positive samples. All these last ten patients had been given intravenous lipid infusions. The rate of positive alveolar macrophages was correlated neither with the plasma triglyceride concentration, nor the Fracture Index Score, nor the delay between the end of the lipid infusion and the BAL. There was no significant difference in PaO2/FIO2 ratio between the patients with positive and negative BAL. Positive BAL was significantly associated with lipid infusions. The data therefore suggest that the presence of fat-laden alveolar macrophages are associated with various pathological pulmonary conditions, particularly aspiration pneumonia and lipid infusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Fat macroglobule formation from chylomicrons and non-traumatic fat embolism

Chylomicrons show calcium-dependent agglutination by C-reactive protein (CRP). This has been suggested as a mechanism by which fat embolism may occur in the absence of trauma. It may also play a role in the pathogenesis of acute pancreatitis in patients with types I and V hyperlipidaemia.

Intralipid microemboli

A baby girl died after receiving intravenous Intralipid. At necropsy a pulmonary Intralipid microembolus, unrelated to the cause of death, was found. Serum taken immediately before infusion agglutinated Intralipid. C reactive protein concentration was raised. This supports the theory that C reactive protein may agglutinate Intralipid in vivo, causing embolisation.