Morphological Stability of Fat Particles in All-in-one Parenteral Nutrition

Abstract

Background: "All-in-one" parenteral nutrition is an accepted method of nutritional support in surgical patients. However, controversy still exists in the stability of fat emulsions, when mixed with other nutritional components and hang for a period of infusion. The general consensus is that particle larger than 5 microns should not be administered, since particle larger than 6 microns increase the risk of fat embolism and may be associated with hemodynamic changes. A study was conducted to evaluate the physical stability of fat particles in parenteral nutrition systems currently practiced in pediatric surgical intensive care unit, Siriraj Hospital, to ensure that it is safe for clinical use.

Material and methods: Seven admixtures of all-in-one parenteral nutrition, actually given for patients in pediatric surgical ICU, were examined under a transmission electron microscope. Each admixture contained glucose (10.47 - 11g/dl), amino acid (0.7 -2.0 g/dl), 20% Intralipid, electrolytes and vitamins in a specific amount tailored for one day infusion of an individual patient. Specimens were collected from hanging bottles at immediately, six and twenty-for hours after mixing. The data were analyzed regarding the average sizes of fat particles, amount of large particles per counting area and maximum particle diameters (D-max.). Comparisons were made between pure 20 % Intralipid and mixed emulsion. Statistical analysis was evaluated by Student's t-test.

Results: Microscopic evidence of instability, such as coalescence was not detected in all samples. Average diameters of fat particles in 20 % Intralipid was 0.418 ± 0.144 microns, whereas particles in admixtures range in size between 0.341 ±0.152 and 0.595+ 0.283 microns. The average particle diameter in four of seven immediate samples was significantly larger than particle sizes in pure emulsion. Five admixtures had increased mean particle sizes at the twenty-forth hour post mixing, compared to the immediate solution. At O, 6th and 24th hour post-mixing, large size (over than 4 microns) were found 0, 0.14 and 0.29 particles per counting area, respectively. No particle larger than 5 microns was detected in all specimens. Maximum diameter of particles (D-max) in pure 20% Intralipid was 1.74 microns whereas D-max in all admixture ranged from 1.3 to 4.65 microns (average 2.50 microns). Average D-max of twenty-forth-hour solution (2.62 microns) are not significantly larger than those of immediate sample (2.01 microns).

Conclusion: Fat particles change their morphology slightly, when mixed in an all-in-one system and hang in room temperature for twenty-four hours. However, stability is still in the acceptable range within one day of infusion.