Page 628 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Parenteral Nutrition 615

interfere with warfarin therapy in human patients. 39,46 osmolarity. The electrolyte composition of these products
The amount of vitamin K found in lipid solutions has varies, but they generally are high in potassium. Therefore
not been reported to cause anaphylactic reactions in they should be used with caution in critically ill patients.
companion animals. When deemed necessary, vitamin K The authors typically use these products as a temporary
supplementation is administered subcutaneously with measure for parenteral nutritional support (i.e., overnight
dosages appropriate for the medical condition. or on weekends) or in combination with low-dose enteral
nutrition. They should be used with care in animals with
Commercial Combination Parenteral renal or hepatic failure because the ratio of protein to
Nutrition Products calories cannot be modified.
Although veterinarians have clinically used single nutrient
solutions (e.g., amino acids or dextrose alone), these COMPOUNDING PARENTERAL
solutions do not provide balanced nutrition and are prob- NUTRITION
lematic when used alone (e.g., 50% dextrose is too
hyperosmolar to be administered through a peripheral The authors recommend using a parenteral nutrient
vein; 5% dextrose is too low in calories to be beneficial admixture, which refers to the inclusion of the dextrose,
when administered alone). If 5% dextrose were amino acids, and lipids (with or without electrolytes,
administered at 66 mL/kg/day to an 11-kg dog, it vitamins, trace elements) in a single bag. The calculations
would provide only 123 kcal/day (<30% of the dog’s cal- of calorie requirements, as well as the amino acid, lipid,
orie requirements and no protein). Administering lipid as and dextrose components for TPN and PPN, are shown
a single solution can suppress immune function and, like in Boxes 25-4 and 25-5.
dextrose, provides no protein. The osmolarity of amino Other methods of calculating parenteral nutrition
42,48,61
acid solutions (1144 mOsm/L) makes them inappropri- formulations have been described, but the
ate for peripheral administration, and if amino acids are methods listed in this chapter reflect the ones currently
provided without sufficient calories, the amino acids will used by the authors. The TPN worksheet produces a par-
be used for calories rather than protein synthesis. There- enteral nutrient admixture with an osmolarity greater
fore, single nutrient solutions should be avoided. than 1000 mOsm/L, and it must be administered via a
However, there are a number of combination products jugular vein. The PPN worksheet produces an admixture
commercially available that combine an amino acid source with an osmolarity less than 700 mOsm/L, which can be
with a calorie source. These are listed in Table 25-3. administered via a peripheral vein, provided that a long,
Because dextrose cannot be sterilized in combination nonthrombogenic catheter is used. Calculating the actual
with amino acids, the approach to these products is to osmolarity of the parenteral nutrition admixture can be
use dual-chamber bags in which the two compartments done using the osmolarity of each component listed in
are separate until the seal between them is broken by Table 25-3 and the equation listed in Box 25-6. The
squeezing the bag and the solutions are mixed (e.g., PPN worksheet is designed for simplicity and not to
Clinimix, Baxter Healthcare Corporation). In another provide optimal proportions of nutrients based on body
product (ProcalAmine, B. Braun Medical Inc., Irvine, weight categories. The rationale for the weight categories
Calif.), glycerin, which can be safely sterilized with amino is that these calculations will provide PPN at approxi-
acids, is used as a calorie source along with the amino mately maintenance fluid rates. Animals with metabolic
acids. The advantages of these commercial combination disturbances or those that require volume restriction
products are their availability and the fact that they may require adjustments in the PPN calculations or
require no compounding. There are several different may require TPN, which allows more flexibility.
formulations of the dextrose/amino acid solutions. Drug-nutrient compatibility is a very critical and very
33,54,68
Lower concentration products (i.e., Clinimix 2.75 amino complex issue for parenteral nutrition. A number
acid in 5% dextrose or ProcalAmine), which have an of deaths have been reported in people from parenteral
osmolarity that allows them to be administered via a long, nutrition because of precipitation of calcium phosphate
33
nonthrombogenic catheter in a peripheral vein (see later in the admixture. At the time of compounding
discussion), provide all of a dog’s (and most of a cat’s) TPN or PPN, some additives can be included using
protein requirements but only 30% to 40% of their energy aseptic technique, but others definitely are not compati-
requirements when administered at maintenance fluid ble. Commonly used drugs that are compatible with
rates (cats, 50 mL/kg/day; dogs, 66 mL/kg/day) by parenteral nutrition admixtures include insulin, heparin,
continuous-rate infusion. Concentrations with higher and metoclopramide. It is strongly recommended that a
concentrations (i.e., Clinimix 5% amino acid in 25% dex- pharmacist experienced in parenteral nutrition
trose) can provide 100% of RER but must be compounding be consulted before considering adding
administered via the jugular vein because of their high anything to parenteral nutrition admixtures.