Page 622 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

610 SPECIAL THERAPY

ROUTE OF NUTRITIONAL that it will not provide all of the animal’s requirements.
SUPPORT Both TPN and PPN are typically a combination of dex-
trose, an amino acid solution, and a lipid solution. How-
Most clinicians have heard the adage, “If the gut works, ever, the concentration of some components (e.g.,
use it.” This approach still holds true, and parenteral dextrose)varies depending onwhether TPN orPPN is cho-
nutrition should not be the first consideration in an ill sen. TPN or PPN can also be formulated with amino acids
9
or injured animal. The suitability of the enteral route anddextrosealone,withoutanylipid. Table25-2compares
should always be addressed first because it is the safest, a PPN and a TPN admixture for a 20-kg dog.
most convenient, most physiologically sound, and least FORMULATION OF PARENTERAL
expensive method of nutritional support (see
26 NUTRITION REQUIREMENTS
Chapter 26. If only parts of the gastrointestinal tract
are functional, consideration should be given to using Calorie Requirements
those functional segments. For example, a dog or cat with When formulating parenteral nutrition, the first step is to
severe esophagitis should be considered a candidate for a determine the animal’s calorie requirements. The
jejunostomy feeding tube. However, when patients are patient’s RER is the number of calories required for
unable to tolerate any enteral feeding, parenteral nutri- maintaining homeostasis while the animal rests quietly.
tion should be considered. Before parenteral nutrition The RER is calculated using the formula:
is instituted, however, it is critical that fluid, electrolyte,
and acid-base abnormalities are corrected. 0:75
RER ¼ 70 ðcurrent body weight in kilogramsÞ
PARENTERAL NUTRITION

Parenteral nutrition can be delivered via a central vein TABLE 25-2 Parenteral Nutrition
(TPN) or a peripheral vein (PPN). TPN, as defined in this (PPN) and Total
chapter, is the provision of all of the animal’s calorie and
protein requirements (and ideally, all of the micronutrient Parenteral Nutrition
requirements as well; see Other Nutrient Requirements (TPN) Formulations
section). PPN only supplies part of the animal’s energy, for 20-kg Dog with
protein, and other nutrient requirements. 74 In this chap- Acute Pancreatitis
ter, we use the abbreviation PPN to refer to partial paren-
teral nutrition, which can be supplied through either a PPN TPN
peripheral or central vein.
5% dextrose (mL) 900 —
Because TPN will supply all of the animal’s calorie and 50% dextrose (mL) — 164
protein requirements, it is usually the modality of choice 8.5% amino acids (mL) 450 312
for an animal requiring parenteral nutrition. The 20% lipid (mL) 77 139
disadvantages are that it requires a jugular venous cathe- Total mL/day 1427 615
ter and it may be associated with more metabolic PPN mL/hr 60 26
complications. PPN may be an alternative to TPN in Maintenance fluid rate (mL/hr) 55 55
selected cases (Box 25-3), but it is important to be aware

BOX 25-3 Indications for Partial Parenteral Nutrition (PPN; i.e., providing less
than the animal's total calorie, protein, and micronutrient
requirements)

• To maintain nutritional status, rather than replete the • When only short-term nutritional support in a
malnourished patient. Debilitated patients should get total nondebilitated patient is anticipated (<5 days).
parenteral nutrition (TPN) or a combination of PPN and • To supplement oral or enteral nutrition.*
enteral nutrition. • When a central vein is not accessible.
• Animals with average nutritional requirements. Those with
high requirements (e.g., open abdomen, large draining
wound, severe vomiting or diarrhea) should receive TPN.

*Whenever possible, enteral nutrition should be used to supplement parenteral nutrition (even if provided at a very low rate) to prevent atrophy
of the intestinal tract.