Background and importance Ternary mixtures in parenteral nutrition (PN) have a complex composition and so interactions between components can lead to instability, compromising safety. Fat globules >5 µm can cause thromboembolisms. Critical aggregation number (CAN) is used to predict stability (calculated with cation concentration).

Aim and objectives To analyse the stability of the lipid emulsion in PN samples with a high CAN using globule size measurements, and to evaluate the influence of temperature and time on emulsion stability.

Material and methods We studied four samples according to the nutritional requirements of a 1 kg neonate during the first days of life. Micronutrient amounts were greater than those recommended, and vitamins and zinc were also added. Samples were prepared in duplicate.

Globule size was measured by laser diffraction (Beckman Coulter LS-I3-320) on the preparation day (day 0) and after 7 days. The samples were stored under refrigerated conditions and at room temperature. CAN was calculated based on the concentrations of cations present in each PN. Statistical analysis was performed using the Student’s t test (statistical significance p<0.05).

Results PN composition is shown in table 1 and average globule size (µm) is shown in table 2.

There were no significant differences between measurements on day 0 and day 7 on samples stored at room temperature or in a refrigerator (p=0.896 and p=0.171, respectively).

Conclusion and relevance Average globule size was stable despite a high CAN of samples, but more sensitive analytical techniques may be necessary to detect changes in the fraction of large globules. The study time and different storage temperature did not influence the average globule size of our samples. To establish the overall stability of the PN, more complete studies should be carried out, analysing more stability dependent processes.

References and/or acknowledgements No conflict of interest.