January 2018 Issue

New Guidance for Using Parenteral Nutrition
By Judith C. Thalheimer, RD, LDN
Today's Dietitian
Vol. 20, No. 1, P. 30

Latest consensus recommendations offer practical clinical guidance for improving practice and decreasing risk across age groups and settings.

Parenteral nutrition (PN), also known as intravenous nutrition, offers a life-sustaining option when intestinal failure prevents adequate oral or enteral nutrition (EN). "PN can provide all required nutrients by vein, thus bypassing the GI [gastrointestinal] tract," says Peggi Guenter, PhD, RN, FAAN, FASPEN, senior director of clinical practice, quality, and advocacy for the American Society for Parenteral and Enteral Nutrition (ASPEN). "It is critically important and life-sustaining for patients with intestinal failure, short bowel syndrome, severe dysmotility, or any other condition where the GI tract is unable to digest, absorb, or metabolize food."

First used successfully in the late 1960s, PN has grown and evolved over the decades and is now used for all age groups in all types of health care settings. However, despite the strides made in research, compounding, infection control, and modes of delivery, PN must be used with caution under the watchful eyes of properly trained experts. "PN is a high-alert, complex, and expensive therapy with risks of complications such as central venous catheter infection, hyperglycemia, hypertriglyceridemia, fluid and electrolyte imbalances, and PN-associated liver disease," Guenter says. "It is essential to have evidence-based criteria for the use of PN so that it is appropriately prescribed, prepared, administered, and monitored."

As part of an ongoing effort to provide clinical guidance regarding PN therapy, the board of directors of ASPEN recently convened a task force to develop new consensus recommendations on the use of PN therapy, with the aim of promoting clinical benefits while minimizing risks. The resulting consensus statement, "When Is Parenteral Nutrition Appropriate?," was published in the March 2017 issue of The Journal of Parenteral and Enteral Nutrition. "These recommendations are designed to identify best practices, reduce variations in practice, and enhance patient safety," says Pat Worthington, MSN, RN, CNSC, nutritional support clinical specialist at Thomas Jefferson University Hospital in Philadelphia and the lead author of the recommendations. "They offer guidance on the issues clinicians in this field struggle with every day."

The high-quality data usually used to create clinical guidelines weren't available for all of the clinical circumstances examined for this project, so the task force opted for consensus recommendations based on weaker supporting literature and expert opinion. The multidisciplinary task force represented nursing, pharmacy, physicians, and dietitians from a variety of specialties. "This was a really great interprofessional committee of high-level experts representing pediatrics, adults, home care, and critical care," Worthington says. "A wide variety of points of view and areas of expertise went into constructing this consensus document."

The recommendations are presented in a question-and-answer format, with each answer broken into multiple parts to address common clinical scenarios in adult, neonatal, and pediatric cases. "Early in the process, the task force identified 14 clinical questions to be addressed," Worthington says. "These fall into the categories of identifying candidates for PN; use of PN in a variety of clinical settings, including palliative, perioperative, and home care; and promoting optimal PN outcomes. A 15th question addresses areas for future research. I think of this consensus recommendation as a sort of road map, meant to be guiding and practical. Clinical practice guidelines are more authoritative, and PN guidelines in the past have been diagnosis based. These recommendations are more based on clinical factors."

Appropriate Candidates for PN
In general, PN should be used in patients who are malnourished or at risk of malnutrition when EN is contraindicated or not tolerated, or when bowel function is inadequate to maintain or restore nutrition status. The recommendations identify five primary areas of GI dysfunction that could impair function sufficiently to warrant PN: impaired absorption or loss of nutrients, mechanical bowel obstruction, need for bowel rest, motility disorders, and inability to achieve or maintain enteral access. "The problem is determining which [patients] need PN and which don't," Worthington says. "For example, not all fistulas require PN."

The recommendations provide a table of clinical signs that indicate GI dysfunction likely to require PN. "A key point that this document addresses is that PN use should not be mandated simply by a diagnosis or condition. It should be based on evaluation of the patient's ability to tolerate oral and/or enteral nutrition," Guenter says. "PN should be reserved for clinical situations in which oral or enteral nutrition is not an option."

Time Frame
The length of time an individual can go without nutrient intake before detrimental clinical effects occur is unknown. Since disease-state metabolism affects nutrient metabolism and utilization, the typical hospitalized patient doesn't follow the classic starvation model, and there's limited data to help make decisions regarding the circumstances in which PN is likely to improve outcomes in high-risk or malnourished patients. The consensus document discusses a reasonable time frame for initiating PN for a variety of patient conditions. They advise initiating PN after seven days for well-nourished adults, within three to five days for those who are nutritionally at risk, and as soon as possible for patients with baseline moderate or severe malnutrition. Patients who are metabolically unstable shouldn't receive PN until their conditions have improved. Very low-birth weight infants should receive PN promptly after birth, but there isn't enough information to suggest a specific time frame for more mature preterm infants or critically ill term neonates. The task force concluded that initiation of PN can be delayed for a week in infants, children, or adolescents with self-limiting illness, but should be started within one to three days in infants or four to five days in older children and adolescents when it's evident they won't be able to tolerate oral intake or EN for an extended period.

Vascular Access
After providing recommendations for determining the appropriateness and timing of PN, the statement addresses vascular access. "Mostly, appropriate PN begins with appropriate device selection," Worthington says. "We included some really specific questions about vascular access that we haven't put a lot of emphasis on in previous recommendations." This includes a discussion on the factors involved in selecting and placing the appropriate vascular access device for PN administration, and when peripheral and intradialytic routes are called for. "There is a perception that a PICC [peripherally inserted central catheter] line is the gold standard for vascular access, but it's not always," Worthington says. "The appropriate device will vary depending on how long the patient is expected to need PN and the care setting. What is appropriate for home and long term care, for example, is different from what is needed for seven days in ICU." The recommendations include a detailed table to assist with selection of appropriate vascular access devices for administering PN. Although use of a central line provides a way around some of the technical problems with peripheral PN, central venous access devices remain leading sources of adverse events related to PN administration, with both central line-associated bloodstream infection and deep vein thrombosis common. "In addition to infection risk, the task force took a good look at risk factors for thrombosis," Worthington says, "which has not received much attention in past guidelines."

Clinical Settings
Several sections of the recommendations deal with the use of PN in special circumstances, including perioperative and palliative care. Since malnourished surgical patients have an increased risk of a variety of negative outcomes, nutrition therapy may be required to reduce complications. The recommendations assert that, while EN is more common in these situations, PN may be necessary in a malnourished patient undergoing GI surgery who can't tolerate EN. Moreover, while rapid transition to oral intake or EN after surgery is ideal, malnourished postoperative patients who are unable to tolerate EN for more than seven days could benefit from PN.

And while adequate nutrition is essential to recovering patients, PN administration doesn't improve nutrition status, reverse cachexia, or improve survival in patients in the final stage of advanced cancer, according to research reviewed by the task force. Nevertheless, the recommendations do address the appropriateness and use of PN in other palliative care situations and include a list of suitability criteria to consider. "Many clinicians may find the palliative care section helpful," Worthington says. "Rather than improvement of nutrition status, symptom management and quality of life become the goals of PN at end of life." In addition to the section on palliative care, the recommendations provide information on which patients are appropriate for home PN therapy and when it's safe to initiate PN in the home setting. There's even a checklist that provides details about the essential elements of assessment and patient/caregiver education for home PN.

Monitoring and Quality Improvement
In addition to advising decisions regarding initiation and management of PN, the consensus statement includes appropriate monitoring parameters. Monitoring should assess progress toward therapeutic goals, the need to adjust a prescription, and when to wean or discontinue PN. "I think the group did a really nice job in helping to outline monitoring parameters," Worthington says. "The statement shows you the way monitoring should be done for different levels of care and a variety of settings. We discuss how often to do certain labs and diagnostic studies, and lay out how the intervals would change for acute care vs long term care." Tables offer guidance for clinical and laboratory monitoring for both adult and pediatric patients in hospital and home care or other alternative settings.

The consensus statement does more than provide recommendations for clinicians; it provides information for organizations on how to track and monitor PN usage for quality improvement. Along with advice on which indicators to monitor, the statement includes a Clinical Audit Checklist to facilitate performance evaluation and improvement. "Very few organizations do any quality improvement centered on PN and safety or even track errors," Worthington says. "This paper provides some guidance on tracking PN appropriateness—sort of a snapshot an organization can use as an internal audit to see how they're doing. We make lots of suggestions for quality improvement projects. I think this is a very valuable segment of the paper."

The final question addressed in the consensus statement looks to the future. In reviewing current evidence and common practice while preparing the document, the task force identified what it sees as major gaps in existing knowledge and urgent issues requiring further research. Research categories addressed include the following:

• PN product-related issues, such as safety and cost-effectiveness of various injectable products, the development of a parenteral vitamin D preparation, and optimal dosing strategy for trace elements in the development of single-entity parenteral multitrace element preparations.

• Patient- and/or disease-focused issues, such as how long a patient experiencing disease state metabolism can go without nutrient intake; timing of PN provision after birth of more mature preterm infants and ways to improve their clinical outcomes; optimal timing to initiate PN in pediatric patients; the benefits, safety, patient tolerability, and cost-effectiveness of high-amino acid PN; the impact of various factors on PN safety in various age groups; and optimal use of PN in several specific clinical circumstances, such as obese home-care patients and patients receiving chemotherapy.

• Administrative and policy-focused issues, such as the question of whether it's acceptable to administer PN through a lumen that has been previously used for other infusions; the cutoff on osmolarity for peripheral PN, and what defines "tolerance" of an infusion; more guiding policy addressing PN in terminally ill patients; and the impact of PN education on the development of PN-associated complications.

The recommendations in this consensus statement are designed for any clinician involved in providing PN, including physicians, nurses, dietitians, and pharmacists, but also for organizations and other stakeholders, such as policy makers and third-party payers. They provide current perspectives regarding the use of PN across the lifecycle and in a variety of health care settings with the ultimate goal of making this remarkable life-saving therapy even safer and more effective.

— Judith C. Thalheimer, RD, LDN, is a nutrition writer and speaker based outside Philadelphia.