In our study we simulated the two endpoints of a typical clinical situation of nutrition therapy. Therefore the duration of inspection was just 24 hours. Under clinical conditions one dose of TPN (usually 1–3 litres for adults) is not administered in a shorter period than 8 hours and not longer than 24 hours. After preparation of the iv solutions we immediately checked the main parameters according to the above mentioned schedule. The comparison of the mode droplet-size values shows that different nutrient test-solutions with and without additional Ca2+
are within the expected droplet size range of 0.2-0.6
μm. The MDS situation of different test mixtures at beginning and at the end of the 24 hour of infusion did not change significantly (Figure ). The large-size tail of the distribution-figure was analyzed at the end of the study in both sites of surface layer and after the port. At 24 hours we realized that in the supernatant phase and in the infusion line small proportion of droplets over 5
μm could be detected. Intensity-weighted distributions (Table ) demonstrate that only in infusion line samples of Kabimix and in the supernatant phase of OliClinomel appeared a second peak of 2552-2883
nm (KA) and 1851-3006
nm (KC) as well as 2277-2816
nm (OA) and 2265-2895
nm (OC) respectively. Exact proportion of over 5
μm droplets could not be estimated in this study.
Mode droplet size values of different fractions of admixtures at the initial (without up or low index) point and after 24 hours.
Appearance of second peak in droplet size and their ratios
Electrokinetic properties of emulsion were demonstrated by measurement of zeta-potential. Test-results explain that mean charge of droplet surface in all samples remained under −30
mV (Table ). It means that the electrokinetic parameter supports droplet size stability features measured with globule-size distribution techniques.
Mean surface charge (mV) of droplets in different TPN mixtures in course of the nutrition period
The ageing of emulsions usually brings increase in droplet-size. In clinical use droplet size stability should be reserved during the time of infusion, in case of intravenous nutrition within 24 hours as well. Our results demonstrate that vast majority of droplet remained within the safe range of under 5000
nm and zeta-potential remained under the safe value of −30
mV. However, in some mixtures oversize droplets were also detected and according to the USP rules fat droplets over 5
μm must not exceed the proportion of 0.05%. Proportions of second peaks are small (Table ), but this range of globule-size is on the borderline and exact number of fat particles over 5000
nm has not been estimated in this experiment. Therefore, from security reasons in these cases use of lipid-filter is reasonable.
It was found an interesting phenomenon. The tendency for separation of large diameter droplets in the two emulsion systems is different. In case of Kabiven second peak of droplets appears in the bottom of the container in contrast to OliClinomel where the second peak appears in the samples taken from the surface layer. Interestingly this phenomenon is independent of calcium-content. From therapeutic point of view we can state that emulsions where the bigger droplets are in the upper layer are safer because infusions are usually infused with a small residual volume and the potentially dangerous big droplets remain in the infusion bag. The difference between the two types of TPN mixtures could be partly explained by the different glucose content and its effect on the osmolarity and the slightly different density of the two emulsions. The higher osmolarity (1190
mOsm/l vs 1060
mOsm/l) and lower density (1.039
g/ml vs 1.049
g/ml) of OliClinomel resulted in droplets of higher particle sizes in the therapeutically safer surface layer [16
]. Further targeted studies can elucidate this phenomenon. Maybe the difference in composition of the oversize droplets could explain the experienced deviation. Nevertheless it is unlikely that droplet-size differences are results of olive oil or soybean oil content.