Protein-energy wasting (PEW) in CKD patients receiving hemodialysis (HD) is a well-documented and highly discussed condition. Patients with severe PEW are at greatest risk and are in need of the most aggressive nutritional interventions.
The various forms of nutritional intervention include education on nutrient-dense foods, recommending oral supplements, enteral feedings through a percutaneous endoscopic gastrosotomy (PEG) tube, intradialytic parenteral nutrition (IDPN), and finally total parenteral nutrition (TPN).
Nutritionists often say: “If the gut works, use it.” Not uncommonly, patients with a functioning GI tract can be severely malnourished because they cannot consume sufficient nutrients to maintain visceral and somatic stores. Ideally, such patients can be provided with a type of supplemental nutrition, such as an oral supplement, enteral/tube feeding, or parenteral nutrition. The supplemental nutrition provided should not have a negative impact on the patients’ appetite or ability to eat and should enhance their overall nutritional status.
Benefits of enteral nutrition
With this criterion in mind, enteral nutrition would be preferable to any form of parenteral nutrition. Enteral nutrition has many benefits: It maintains the gut villi, prevents bacterial translocation, and is less expensive than parenteral nutrition. Unfortunately, inserting a tube via the nose or a more permanent insertion into the stomach can lower a patient’s perceived quality of life, and physicians may not use this intervention as frequently as it is indicated.
Patients receiving HD have existing accesses that can tolerate high osmotic solutions, such as parenteral nutrition. Parenteral nutrition is commonly composed of glucose, amino acids, and lipids and can contain a multivitamin. IDPN can be delivered through the patient’s existing dialysis access. This approach is similar to providing an oral supplement except that the nutrients are absorbed directly into the bloodstream.
An article by Dukkipati et al (Am J Kidney Dis. 2009; published online ahead of print) recently outlined the advantages and disadvantages of IDPN.
Some of the advantages described in this review include the ability to provide nutritional support without being reliant upon or impacting the patient’s appetite, nutritional composition that can be regulated or individualized to the patient’s specific requirements, and the possibility of removing excess fluid or minerals provided by IDPN during the dialysis session. Some of the disadvantages of IDPN were that it is provided only on dialysis days, i.e., three to four times per week; nutrients are cleared rapidly from the blood; the GI tract is not being used; and cost.
Because the efficacy of IDPN has long been controversial, clinicians have been hesitant to prescribe it for their patients. However, growing evidence demonstrating efficacy may result in clinicians’ reassessing the use of this nutritional intervention. In their article, Dukkipati and colleagues reviewed studies conducted since 1975. Two of the most compelling studies were led by Ikizler in 2002 and Cano in 2007.
The 2002 study demonstrated that providing either oral supplementation during a dialysis session or IDPN could lead to improved protein balance of HD patients (Am J Physiol Endocrinol Metab. 2002;282:E107-E116). The researchers used stable isotopes to measure protein synthesis and degradation before and after IDPN administration in seven clinically stable patients. Net total-body protein balance was significantly more positive when the patients received IDPN than when they did not. This could result in an increase in visceral protein status, which is ultimately associated with fewer hospitalizations and better survival.
The second study, conducted in 2007 by Cano et al, was a randomized clinical trial in which malnourished patients received oral supplementation or oral supplements plus IDPN (J Am Soc Nephrol. 2007;18:2583-2591). In this study, no differences in nutritional outcomes were observed between the groups; however, both groups had improved nutritional status.
Therefore, although the primary hypothesis was not proven, a secondary and possibly more important result was found. Nutritional intervention (whether oral supplements or oral plus IDPN) resulted in improved nutritional status. Additionally, statistically significant improvements in both albumin and prealbumin occurred even when inflammation (defined as C-reactive protein levels of 10 mg/L or higher) was present.
Ultimately, improving nutritional status means better quality of life and longer survival for HD patients. Using nutrition appropriately yet aggressively is very important and should not be overlooked in the face of pharmaceutical treatments. If the patient cannot consume sufficient kilocalories through oral supplements and is unwilling to use enteral nutrition, IDPN is an effective nutritional intervention.
Furthermore, IDPN is covered by both Medicaid and Medicare part D (nonhospitalized patients) and part A (hospitalized patients). Clinicians whose CKD patients are on HD and have severe PEW or are at risk for having severe PEW should consider all the possible nutritional interventions available and choose the one best suited to each patient.
Dr. Steiber is Coordinator of the Dietetic Internship/Master’s Degree Program at Case Western Reserve University in Cleveland.