Quality of parenteral nutrition mixtures: is it improved by the use of an automated compounding device?

Since November 2011, parenteral nutrition mixtures (PN) are prepared with an automated compounding device (ACD) : Exacta Mix 2400.

After one year of ACD use, we compared the quality of PN mixtures prepared manually and with the ACD.

A PN mixture is considered acceptable if the difference between the measured value and the expected value is ± 3% for weight, and ±10% for sodium and potassium concentrations. These values were analyzed using the STAT A software. We used the Pearson correlation test, Khi2 test and Bland-Altman method.

This study was conducted over a period of one year and two months: 5months before and 9 months after setting up the ACD.

We analysed the data from 1125 mixtures prepared manually and 2146 mixtures prepared with theACD.

The Pearson correlation test shows that, for the 3 parameters there is a strong positive correlation between measured and expected values, regardless the of the PN mixtures’ preparation method.

The Khi2 test shows the ACD significant improved (p <0.001) the compliance of PN mixtures : percentages of non-compliance are respectively of 21.33%, 6.13% and 5.78% in terms of weight, sodium and potassium concentrations in manual preparation, versus 0.70%, 2.47% and 0.52% with the ACD.
The high non compliance values of the mixture’s weight with the manual method can be explained by the addition of large volumes of water or glucose. These volumes are more difficult to measure accurately during a manual preparation.

The Bland-Altman representation shows that, for the 3 parameters, the ACD tends to produce more homogeneous values than when the preparation is done manually (pharmacy technician dependent).

These results confirm that the more accurate volumes obtained with the ACD directly influence the quality of PN mixtures.

However, even if this improvement is significant, it’s real gain is low because of the good initial quality of the preparations made manually.