Calculating the refractive index for pediatric parenteral nutrient solutions.
OBJECTIVE
The utility of refractometric analysis for calculating the refractive index (RI) of compounded parenteral nutrient solutions for pediatric patients was examined.


METHODS
An equation for calculating the RI of parenteral nutrient solutions was developed by chemical and linear regression analysis of 154 pediatric parenteral nutrient solutions. This equation was then validated by analyzing 1057 pediatric parenteral nutrition samples. The RI for the parenteral nutrient solutions could be calculated by summing the RI contribution for each ingredient and then adding the RI of water. The RI contribution for each ingredient was determined by multiplying the RI of the manufacturer's concentrate by the volume of the manufacturer's concentrate mixed into the parenteral nutrient solution divided by the total volume of the parenteral nutrient solution.


RESULTS
The calculated RI was highly correlated with the measured RI (R(2) = 0.94, p < 0.0001). Using a range of two standard deviations (±0.0045), 99.8% of the samples fell into the comparative range. RIs of electrolytes, vitamins, and trace elements in the concentrations used did not affect the RI, similar to the findings of other studies.


CONCLUSIONS
There was no statistical difference between the calculated RI and the measured RI in the final product of a pediatric parenteral nutrient solution. This method of quality control can be used by personnel compounding parenteral nutrient solutions to confirm the compounding accuracy of dextrose and amino acid concentrations in the final product, and a sample can be sent to the hospital laboratory for electrolyte verification.
College of Pharmacy, University of Utah (UU), East Salt Lake City, UT, USA. scott.nelson2@imail.org
Scott
S
Nelson
Jason
J
Barrows
Richard
R
Haftmann
Michael
M
Helm
Mark
M
MacKay
D000596:Amino Acids / Q000737:chemistry; D002648:Child; D004339:Drug Compounding / Q000379:methods*; D004573:Electrolytes / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D006801:Humans; D016014:Linear Models; D057947:Parenteral Nutrition Solutions / Q000737:chemistry*; D011786:Quality Control; D012031:Refractometry / Q000379:methods*; D014131:Trace Elements / Q000737:chemistry; D014815:Vitamins / Q000737:chemistry
D000596:Amino Acids; D004573:Electrolytes; D057947:Parenteral Nutrition Solutions; D014131:Trace Elements; D014815:Vitamins; D005947:Glucose