The selected oligomeric formula is ready-to-use and in a closed-system bag;

therefore, bacterial contamination from mixing technique is not of concern.

Cleanliness during formula transfer to the delivery bag, the period of time formula is

in the bag, and methods of cleaning the delivery bag may contribute to bacterial

contamination of formula. J.N. is receiving formula from a closed enteral system

(i.e., ready-to-hang formula-filled containers), and this virtually eliminates transferrelated contamination when proper technique is used. Any addition (e.g., medication,

carbohydrate, fat or protein module, MCT oil) to the prefilled container before

hanging can contaminate the system, and guidelines (e.g., hang-time, set changes) for

an open enteral system then apply. Even when administered separately from the

formula, modular components are a potential contributor to diarrhea due to their

osmolarity and potential contamination during preparation and administration. The

selected formula does not meet J.N.’s protein requirement; therefore, a modular

protein is needed to supplement the enteral formula. The nutrition plan includes

addition of a modular protein component; however, on review of the medication

administration record, this has been started.

Medications are a major contributor to diarrhea in tube-fed patients.

30,36,77–79 J.N.

currently receives antibiotics and has for some time. However, the prevalence of

diarrhea with antibiotic therapy is difficult to determine due to failure to report stool

frequency and consistency as well as lack of a clear definition of diarrhea. C.

difficile may have relapsed after his previous treatment. Stool specimens should be

sent for culture and/or C. difficile toxin. Evaluation of J.N.’s medications may reveal

medications associated with diarrhea (e.g., sorbitol-containing products, antacids,

oral magnesium, potassium chloride, phosphate supplements, H2

receptor

antagonists) for which therapeutic alternatives or different routes of administration

could be considered.

28,36 High-osmolality liquid medications should be diluted before

administration to reduce GI side effects.

34,35,65,66

J.N.’s GI tract should continue to be used to the extent possible. EN appears to be

better than PN for maintaining the GI tract barrier and host immunologic

function.

4,18–20

,

49,55 Both the CCP and SCCM–ASPEN guidelines recommend use of

EN over PN in critically ill patients.

4,18–20 Both guidelines also recognize the need for

PN at some point when EN cannot meet the patient’s nutritional requirements;

however, neither guideline addresses patients with long-term, chronic critical illness

such as J.N. The risk of sepsis increases without enteral stimulation of the GI tract.

Whether this occurs through bacterial translocation, an unproved process in humans

in which enteric bacteria or endotoxin crosses the GI mucosa into mesenteric lymph

nodes and portal circulation, or through another mechanism is unclear. In addition,

the GI tract serves an immune function, especially with respect to IgA secretion.

Respiratory tract infections, such as pneumonia, may increase without proper

stimulation of the GI tract, owing to less-effective protection from IgA. Compared

with PN, EN attenuates catabolism in highly stressed patients, although initiation of

feedings soon after the stressing event may be required to obtain this response.

Before a decision is made to stop J.N.’s EN, all possible causes of diarrhea should

be investigated. Possible benefits of improved fluid and electrolyte balance from

stopping EN should be weighed against the potential benefits of reduced infections

from continued use of the GI tract. Combined EN plus PN can also be considered,

especially if J.N. tolerates partial EN but cannot advance to goal rate. Full PN should

be provided if EN is stopped for more than 1 or 2 days.

KEY REFERENCES AND WEBSITES

A full list of references for this chapter can be found at

http://thepoint.lww.com/AT11e. Below are the key references and websites for this

chapter, with the corresponding reference number in this chapter found in parentheses

after the reference.

Key References

Bankhead R et al. Enteral nutrition practice recommendations. JPEN J Parenter Enteral Nutr. 2009;33:122. (35)

Mueller C et al, eds. The A.S.P.E.N. Adult Nutrition Support Core Curriculum. 2nd ed. Silver Spring, MD:

American Society for Parenteral and Enteral Nutrition; 2012. (2, 3, 7, 21, 26, 37, 52, 65)

McClave SA et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult

Critically Ill Patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and

Enteral Nutrition (A.S.P.E.N.). JPEN J Parenter Enteral Nutr. 2016;40(2):159-211. (4)

Dhaliwal R et al. The Canadian Critical Care Nutrition Guidelines in 2013: an update on current recommendations

and implementation strategies. Nutr Clin Pract. 2014;29(1):29. (20)

Kraft MD et al. Review of the refeeding syndrome. Nutr Clin Pract. 2005;20:625. (25)

Key Websites

American Society for Parenteral and Enteral Nutrition. http://www.nutritioncare.org and

http://www.nutritioncare.org/Guidelines_and_Clinical_Resources/Clinical_Guidelines/. To access

content for:

McClave SA et al. Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult

Critically Ill Patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and

Enteral Nutrition (A.S.P.E.N.). JPEN J Parenter Enteral Nutr. 2016;40(2):159-211. (4)

McMahon MM et al. A.S.P.E.N. clinical guidelines: nutrition support of adult patients with hyperglycemia.

Nutr Clin Pract. 2013;37910:23. (64)

Bankhead R et al. Enteral Nutrition Practice Recommendations—[Endorsed by the American Dietetic

Association (ADA), the American Society of Health-System Pharmacists (ASHP) and the Institute for Safe

Medication Practices (ISMP)]. J Parenter Enteral Nutr. 2009;33:122. (35)

Heyland DK et al. Canadian Clinical Practice Guidelines. Summary of topics and recommendations. Critical Care

Nutrition. J Parenter Enteral Nutr. 2003;27:355. http://www.criticalcarenutrition.com/index.php?

option=com_content&review=article&id=18&Itemid=10. Accessed August 20, 2015. (19)

Global Enteral Device Supplier Association (GEDSA). Stay Connected initiative. Enhancing patient safety.

http://www.StayConnected2015.org. (38)

Dhaliwal R et al. The Canadian critical care nutrition guidelines in 2013: an update on current recommendations

and implementation strategies. Nutr Clin Pract. 2014;29(1):29-43. www.criticalcarenutrition.com/cpgs/2013.

Institute for Safe Medication Practices (ISMP). Oral dosage forms that should not be crushed.

http://www.ismp.org/Tools/DoNotCrush.pdf. Accessed July 21, 2015. (70)

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p. 790

Parenteral nutrition (PN) formulations are complex intravenous (IV)

admixtures that require strict adherence to safe compounding practices.

Case 38-2 (Questions 5-8),

Case 38-3 (Question 8),

Case 38-4 (Question 7),

Tables 38-1, 38-2 and 38-4

Parenteral nutrition (PN) is indicated in patients with a nonfunctioning

gastrointestinal tract. Patients should be assessed for appropriate

indications of the use of PN.

Case 38-2 (Question 1),

Table 38-3

Calories, protein, fluid, electrolytes, vitamins and minerals are based on

the patient’s individual needs and are determined by baseline nutritional

status, medical history, clinical presentation and IV access.

Case 38-1 (Questions 1-6),

Case 38-2 (Question 4),

Case 38-3 (Questions 1, 4, 5

and 9),

Case 38-4 (Question 1, 2, 4

and 5), Tables 38-6–38-8

Before PN is initiated, the practitioner must be aware of potential

metabolic and respiratory complications, including refeeding syndrome,

increased carbon dioxide production, and hyperglycemia. Appropriate

fluid, macronutrient, and micronutrient adjustments to specialized

nutrition support must be implemented to avoid or diminish the expected

complications.

Case 38-2 (Questions 3 and

9), Case 38-3 (Questions 2,

3, and 6, 7), Case 38-4

(Question 3)

Appropriate monitoring of the patient’s vitalsigns, body weight,

temperature, serum chemistries, hematologic indices, nutrition intake,

and fluid intake and output are essential to determine the success of PN

therapy and to make changes in therapy.

Case 38-2 (Question 9),

Case 38-3 (Question 7),

Table 38-5

Advancements in the delivery of home PN have increased patients’

acceptance and empowered engagement in self-care. An understanding

of the patient’s fluid and nutrient needs is essential for optimal delivery

of home PN, to help ensure positive outcomes and the best quality of

life for the patient.

Case 38-4 (Questions 5 and

6)

Practitioners should be aware of the additional complications associated

with home (or long-term) delivery of PN including hepatobiliary

complications, metabolic bone disease, and catheter-related

complications.

Case 38-4 (Questions 7–9)

Fluid requirements, macronutrient selections, electrolyte quantities, and

vitamin and mineral alterations may be warranted in patients presenting

with hepatic or renal failure, short bowelsyndrome, obesity, diabetes,

pancreatitis, and respiratory failure.

Case 38-1 (Question 2),

Case 38-3 (Questions 1-3),

Case 38-4 (Questions 3 and

5)

It has long been established that a patient’s nutritional status directly impacts

recovery from illness or injury. Malnutrition is associated with multiple

complications including poor wound healing, infection, prolonged hospital stays, and

increased mortality.

1 The preferred method of providing nutritional support is through

the gastrointestinal (GI) tract. If using the GI tract is not feasible, intravenous feeding

is an option. For centuries clinicians attempted intravenous feeding using crude

intravenous cannulas and nutritional substances ranging from olive oil to cow’s milk.

Unfortunately, historical attempts at using the vascular system for nutritional support

were fraught with challenges. Clinicians were limited by the amount of calories

administered, lack of reliable intravenous (IV) access, and risk of infection because

of a lack of sterility.

2

The advent of central venous catheters (CVCs) in the 1960s ushered in the

contemporary practice of intravenous feeding—parenteral nutrition (PN) therapy.

CVCs allow the administration of concentrated nutritional admixtures that

p. 791

p. 792

are rapidly diluted in the systemic circulation. Prior to the development of central

catheters, peripheral catheters were used which limited the amount of calories and

nutrients that could be safely administered.

3

VENOUS ACCESS SITES

PN formulations are administered through peripheral or central veins. The type of

venous access utilized primarily depends on the anticipated duration of therapy and

nutrient requirements of the patient.

1

Peripheral Venous Access

Peripheral venous access is generally the route of choice when PN is expected to be

utilized for less than 10 days and when energy and protein requirements are low to

moderate. Patients requiring peripheral parenteral nutrition (PPN) must have good

peripheral venous access and must be able to tolerate large volumes of fluids,

because of the low concentrations of dextrose and amino acids used in PPN

formulations.

4

PN formulations are hypertonic and irritating to peripheral veins. In adults, the

osmolarity of PPN formulations should be maintained below 900 mOsm/L (normal

serum osmolality 280–300 mOsm/L) to minimize vein irritation and patient

discomfort. With peripheral venous access, low final concentrations of dextrose

(5%–10%) and amino acids (3%–5%) are necessary and frequent venous access site

rotation (every 48–72 hours) is required. Several liters of PPN may be needed daily

to meet energy and protein needs of the patient because of the dilute nature of the

peripheral admixture. Caloric density of peripheral formulations is less than 1

kcal/mL and can be increased by administering intravenous lipids concurrently or by

adding lipids to the dextrose and amino acid mixture. Lipids may protect the vein

against irritation through dilution and by a buffering effect.

5,6

Central Venous Access

Central venous access is the preferred route of administration of PN formulations for

patients who have a nonfunctional GI tract, require bowel rest for more than 7 days,

have limited peripheral venous access, or have energy and protein needs that cannot

be met with peripheral nutrient formulations.

1,4,7

Traditionally, the CVC is percutaneously inserted into the subclavian vein and

threaded through the vein so the tip rests in the upper portion of the superior vena

cava (SVC) just above the right atrium. A newer catheter technique involves the use

of a peripherally inserted central catheter (PICC) that is inserted in the antecubital

vein and advanced until the end of the catheter reaches the upper SVC.

7–9 The internal

and external jugular veins may also be used to thread a catheter into the SVC;

however, maintaining a sterile dressing on these sites is more difficult than with the

subclavian or PICC approach. The SVC is an area of rapid blood flow, which

quickly dilutes concentrated parenteral nutrient formulations, thereby minimizing

phlebitis or thrombosis. Some patients are not candidates for placement of catheters

in the SVC and require a femoral vein insertion with the tip of the catheter in the

inferior vena cava. There may be a greater risk for infection with catheters placed

using this technique.

6,7

Differing from PPN, parenteral nutrient formulations designed for administration

through central veins often contain relatively high concentrations of dextrose (20%–

35%) and amino acids (5%–10%), plus lipids. The central PN formulation typically

provides a caloric density greater than 1 kcal/mL and an osmolarity greater than

2,000 mOsm/L. Central PN formulations are often termed total PN because complete

nutrient needs of the patient may be delivered by this route.

COMPONENTS OF PARENTERAL NUTRIENT

FORMULATIONS

PN formulations are complex mixtures containing up to 40 different nutrient

components, including energy substrates such as carbohydrate (dextrose), protein

(amino acids), and fat (lipid or IV fat emulsion), along with water, electrolytes,

vitamins, and trace minerals. Various combinations of these components are prepared

under aseptic conditions based upon individual patient needs.