Page 633 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

620 SPECIAL THERAPY

underlying disease rather than being related to parenteral Discontinuing Parenteral Nutrition
nutrition. However, another indirect link exists between Transitioning to oral intake or enteral nutrition should be
sepsis and parenteral nutrition. An increased risk for bac-
done as soon as possible to prevent the problem of
terial translocation is present because villous atrophy
gut atrophy that is associated with lack of oral intake.
occurs when an animal is fed parenterally (i.e., when
In veterinary medicine, parenteral nutrition typically is
the animal is not receiving any nutrients via the enteral
administered for less than 1 week. However, it is impor-
route). This factor is another argument for reinstituting
tant to ensure that the patient is tolerating oral intake or
oral or enteral nutrition as soon as possible in animals
enteral nutrition and is ingesting sufficient amounts (at
receiving parenteral nutrition.
least 50% of RER) before discontinuing parenteral nutri-
The other critical aspect in reducing the risk of
tion. Once the patient is able to eat, it should be offered
complications is vigilant monitoring. Checking the cath-
food regularly to assess its appetite, or a feeding tube
eter site daily can identify malpositioning of the catheter
should be placed if the animal is anorectic. When the ani-
and phlebitis or cellulitis early, before serious problems
mal is voluntarily consuming or enterally receiving at least
develop. Body weight should be monitored daily in
50% of RER, TPN can be gradually decreased over a
animals receiving parenteral nutrition. Fluid shifts also
period of 4 to 8 hours (while monitoring blood glucose
can explain rapid changes in weight during hospitaliza-
concentration). To accomplish this withdrawal, TPN is
tion, emphasizing the need for continued nutritional administered at half the calculated rate for 4 to 8 hours
assessment. Use of the RER as the patient’s caloric and then discontinued completely. If TPN is discontinued
requirement is merely a starting point. The number of abruptly, there is a small risk of rebound hypoglycemia.
calories provided may need to be increased to prevent PPN can be discontinued abruptly without this gradual
weight loss or to keep up with the patient’s changing decrease.
needs. To prevent complications with parenteral nutri-
tion, the patient should be monitored carefully and fre- How to Obtain Parenteral Nutrition
quently. Body temperature, heart rate, and respiratory To compound the parenteral nutrient admixtures (dex-
rate should be recorded several times a day. Metabolic trose, amino acid, and lipid) calculated using the TPN
complications can occur frequently in animals receiving and PPN worksheets provided in this chapter, there are
parenteral nutrition, and monitoring is crucial to detect
a number of different options. One option is an
and address them early, if necessary. The clinical situation
automated compounder, which provides quick and accu-
should dictate the frequency and spectrum of monitoring
rate mixing. However, these compounders are expensive
required because some patients will need more intensive
and usually are not cost-effective unless parenteral nutri-
monitoring. Each case is individual, and good clinical
tion is used frequently. A second option for compounding
judgment is imperative. In animals receiving parenteral
parenteral nutrition solutions manually is using a three-
nutrition, the authors recommend that general attitude,
in-one bag (Empty three-in-one mixing container with
body weight, temperature, blood glucose concentration,
attached 3-lead transfer set, Abbott Laboratories; All-
total solids (check the serum for gross lipemia or hemo-
in-One Container for gravity transfer, Baxter Healthcare
lysis), and serum electrolyte concentrations should be
Corp.). These bags have three attached leads that can be
assessed daily or more frequently if indicated. Other
connected using aseptic technique to bags of dextrose,
variables that may require monitoring include ammonia
amino acids, and lipids, respectively. The components
(for animals that are at risk of developing hepatic enceph-
then are added to the recipient bag in a closed system
alopathy), triglycerides (for those with gross lipemia), and by gravity. To make this system more accurate, the recipi-
bilirubin. The development of metabolic abnormalities ent bag should be weighed to ensure that an accurate
usually does not require discontinuation of parenteral amount of each solution is added, especially in very small
nutrition but may require reformulation (e.g., a reduc- animals. Like the automated compounder, these all-in-
tion in the lipid content for animals that develop hypertri- one bags require a knowledgeable person to perform
glyceridemia). Box 25-7 lists the methods that can be the compounding, a very clean environment, and good
used to reduce the risk of the common complications. aseptic technique. Many hospitals that do not use paren-
Other variables to monitor include gastrointestinal signs teral nutrition frequently do not find this method to be
and appetite so that enteral nutrition or oral intake can be time- or cost-effective. Alternatives include making
initiated as soon as possible. Finally, the overall nutritional arrangements with a large veterinary referral hospital that
plan should be reassessed on a regular basis so that it can
compounds parenteral nutrition or with a human hospital
be adjusted to meet the animal’s changing needs. For
in the community. Another solution that has worked very
example, an animal receiving PPN for 3 days may need
well for many veterinary hospitals is to make arrangements
to be switched to TPN if its underlying disease has not
with a human home health care company. These
resolved, or a small amount of enteral nutrition can be
companies compound parenteral nutrition for human
introduced in conjunction with PPN if tolerated.
patients who often are receiving it for many years in their