Page 427 - Nutrition Essentials for Nursing Practice

C H A P T E R 1 5 Feeding Patients: Oral Diets and Enteral and Parenteral Nutrition 415

possible after admission and resuscitation when EN is not feasible (McClave et al., 2009).
PN is never an emergency procedure, and it should be discontinued as soon as possible.

Catheter Placement

Central PN: the PN may be infused via peripheral or central veins. Peripheral parenteral nutrition (PPN)
infusion of nutrients is not widely used because solutions infused into peripheral veins must be isotonic (i.e.,
into the bloodstream by they must have low concentrations of dextrose and amino acids) to prevent phlebitis and
way of a central vein. increased risk of thrombus formation. Because the caloric and nutritional value of PPN is
Central PN solutions limited, it is best suited for patients who need short-term nutrition support (7–10 days) and
are nutritionally do not require more than 2500 cal/day. PPN is contraindicated in patients who need a fluid
complete. restriction, such as in patients with renal failure, liver failure, or congestive heart failure.

Central PN infuses a hypertonic, nutritionally complete solution through a large-
diameter central vein so that it is quickly diluted. A physician threads a central venous
catheter through the jugular or subclavian vein until the tip is located just above the heart.
Specially trained nurses can place a peripherally inserted central catheter (PICC) at bedside.
The line is usually inserted on the inside of the elbow and threaded so the tip of the catheter
rests at the superior vena cava.

Composition of PN

PN solutions provide protein, carbohydrate, fat, electrolytes, vitamins, and trace elements
in sterile water. They are “compounded” or mixed in the hospital pharmacy, either
manually by the pharmacist or through automated compounding equipment, which allows
individualization of the solution based on the patient’s fluid and nutrient requirements.
Automated compounders can mix a 24-hour batch of PN solution into a single container,
that is, either a two-in-one formula (dextrose and amino acids) or a three-in-one formula
(dextrose, amino acids, and lipids). Most hospitals use a two-in-one system and deliver
lipids separately.

Protein

Protein is provided as a solution of crystalline essential and nonessential amino acids with
the amounts of specific amino acids varying insignificantly among manufacturers. Amino
acid solutions range in concentration from 3.5% to 15%, providing 30 to 150 g protein/L,
respectively. Amino acid formulations are available with and without electrolytes. Specially
modified amino acid solutions are available for renal failure, liver failure, and high stress,
although there is little evidence supporting the use of any of these solutions (Academy of
Nutrition and Dietetics Evidence Analysis Library, 2012).

Carbohydrate

Dextrose: another The carbohydrate used in parenteral solutions in the United States is dextrose monohy-
name for glucose. drate, which provides 3.4 cal/g. It is available in concentrations ranging from 5% to 70%,
providing 50 to 700 g/L, respectively. Only concentrations at 10% or less are recommended
for PPN so as to avoid damage to the peripheral vein. The minimal amount of dextrose rec-
ommended in PN is 100 to 125 g/day for adults; the maximum is 5 mg/kg/min (Academy
of Nutrition and Dietetics Evidence Analysis Library, 2012). Although carbohydrate is
an important energy source, giving a patient too much can have negative consequences.
Hyperglycemia is associated with immune function impairments and increased risk of infec-
tious complications. A high carbohydrate load may also lead to excessive carbon dioxide