Manual of Clinical Nutrition Management B- 50 Copyright © 2013 Compass Group, Inc.
PARENTERAL NUTRITION SUPPORT FOR ADULTS
Overview
Parenteral nutrition is the provision of nutrients intravenously. Since the 1960s, major advances have been
seen in the technique, delivery, and formulation of parenteral nutrition (1). The use of guidelines for practice
has improved nutritional markers and reduced the rates of complications of patients receiving parenteral
nutrition (1,2). The two primary types of parenteral nutrition are central parenteral nutrition (CPN) and
peripheral parenteral nutrition (PPN).
In CPN (or total parenteral nutrition), nutrients are provided through a large-diameter vein, usually the
superior vena cava, by access of the subclavian or internal jugular vein. The CPN formulas are hyperosmolar
(1,300 to 1,800 mOsm/L) and consist of dextrose (15% to 25%), amino acids, and electrolytes to fully meet
the patient’s nutritional needs. The nutrient and fluid composition of CPN can be adjusted to meet the
individual needs of patients who require fluid restriction (3). When venous access for the delivery of nutrients
is required for longer than 2 weeks, CPN is indicated because it can be maintained for prolonged periods (1).
In PPN, a peripheral vein provides venous access. This form of parenteral nutrition is similar to CPN except
that lower formula concentrations must be used because the peripheral vein can only tolerate solutions that
are less than 900 mOsm/L. Compared with CPN formulas, PPN formulas have lower concentrations of
dextrose (5% to 10%) and amino acids (3%). Because higher concentrations cannot be infused into the
peripheral vein, PPN requires larger fluid volumes to provide energy and protein doses comparable to the
doses provided by CPN. The larger fluid volume poses a challenge for patients who require fluid restriction.
The maximum volume of PPN that is usually tolerated is 3 L/day (125 mL/hour). Repletion of nutrient stores
is not a goal of PPN, and it should not be used in severely malnourished patients (1). The use of PPN is
indicated only for mildly to moderately malnourished patients who are unable to ingest adequate energy
orally or enterally, or for patients in whom CPN is not feasible. Typically, PPN is used for short periods (5
days to 2 weeks) because of limited tolerance and the vulnerability of peripheral veins (eg, risk of peripheral
venous thrombophlebitis) (1).
Nutrition Assessment
A meta-analysis of parenteral nutrition suggests that this route of nutrition support increases infection rates
without measurable beneficial outcomes when compared to controls (4). Parenteral nutrition is costly and
may result in serious complications and risks if the patient is not monitored closely (5,6). Steps must be taken
to maximize the benefit and efficacy of parenteral nutrition while reducing the inherent risks of
hyperglycemia, immune suppression, increased oxidative stress, and potential infectious morbidity (6).
Patients who are candidates for parenteral nutrition must be carefully evaluated, and steps must be taken to
provide the most effective dose, content, monitoring process, and supplemental additives (6).
Indications (1-3)
Guidelines for the implementation of parenteral nutrition have been developed by the American Society for
Parenteral and Enteral Nutrition (ASPEN) (1,6). Parenteral nutrition is indicated for patients who are unable
to receive adequate nutrients via the enteral route (eg, patients who have a nonfunctional or severely
compromised gastrointestinal tract). The indications for parenteral nutrition include (1,3,6,7):
malnutrition when enteral nutrition is not feasible (6)
major surgical procedures where the preoperative assessment indicates that enteral nutrition is not
feasible through the perioperative period, and the patient is malnourished (6)
perioperative support of moderately to severely malnourished patients with gastrointestinal cancer
after 7 days of hospitalization when enteral nutrition has not been feasible or has been insufficient to
consistently meet the target energy goal (6)
severe malabsorption caused by massive bowel resection (≥ 70% resected) or severe diarrhea
intractable vomiting
severe acute, necrotizing pancreatitis in patients who have a history of poor tolerance to enteral nutrition
or for whom enteral feeding is not possible at or beyond the ligament of Treitz (6,8,9) (Parenteral nutrition
should not be initiated until after the first 5 days of hospitalization.) (6)
paralytic ileus requiring prolonged bowel rest
complete intestinal obstruction
enterocutaneous fistula with an output greater than 500 mL/day (A trial of enteral nutrition can be