Diagram for Easy Determination of the Fat Emulsion Amount in Total Parenteral Nutrition

Abstract

Total parenteral nutrition (TPN) is a well-established method for providing nutrition in surgical patients. Fat emulsion is an important component of TPN not only as a high-energy source but also as a source of essential fatty acids. However, the recommended amount of lipid administration varies from author to author, and it is not clearly shown in most formulae. The aim of this study was to make a table for an adequate amount of fat emulsion with different mixtures of amino acids and dextrose solution, all of which being within the normal range (100 : 1 ∼ 150 : 1) o( nonprotein calories-nitrogen ratio (NCNR). The total nonprotein calories were calculated by multiplication of the nitrogen (weight) and the NCNR of normal ranges. The difference between the total nonprotein calories and the calories from the dextrose solution was the energy from the lipid emulsion and was converted to the volume of 10% fat emulsion solution (Y-axis). Dextrose solutions were already classified according to concentrations (15%, 17.5%, 20%, 22.5% and 25%). The ratio of calories from the lipid emulsion to those from the total nonprotein was calculated, and the values ranging from 20% to 60% were selected as the recommended volume. The numbers on the X-axis were the volumes of 8.5% amino-acid solution. Six oblique lines with different slopes could be gotten from the different concentrations of the dextrose solution and represented NCNRs of 100 : 1, 110 : 1, 120 : 1, 130 : 1, 140 : 1, and 150 : 1. The highest points for the six oblique lines were 60% nonprotein calories, and the lowest points were 20% nonprotein calories. The area between the upper imaginary line collecting all the highest points of the six oblique lines and the lower imaginary line connecting all the lowest points of six oblique lines was a complex of points providing the ideal NCNR and the ideal amount of fat emulsion in various volumes of 8.5% amino-acid solution in certain concentrations of dextrose solution. We conclude that such graphs can be used in a situation when modification of the formula is required during TPN.