In instances when the gastrointestinal tract is not functioning properly (such as in certain types of cancers, post-GI surgeries, and traumas), tube feeding may not be feasible or safe. In these cases, parenteral nutrition (PN) would be the option. It is a liquid mixture of dextrose (carbohydrate), protein, fats, vitamins, and minerals given intravenously into the blood. Peripheral parenteral nutrition (PPN) is when the nutrition is provided through a vein in a limb, or peripherally. This type of access limits the volume and osmolarity of parenteral nutrition but is acceptable for up to two weeks.
Total parenteral nutrition (TPN), on the other hand, is when the nutrition is delivered through a central vein into the superior vena cava. Because the size of the vein is larger, it can tolerate higher volume and osmolarity better and can be used for long-term parenteral nutrition therapy. To receive parenteral nutrition, patients have to be hemodynamically stable, have an appropriate care plan that allows artificial nutrition, and expected not to be able to eat or use their bowels for more than 5-7 days. The benefits of parenteral nutrition are negligible if only provided for just a few days.
Because the parenteral nutrition device comes with a catheter, a major concern with parenteral nutrition is the risk of catheter infection and catheter-related sepsis. The catheter exit site should be cleaned with an appropriate antiseptic agent such as 70% alcohol, 10% povidone-iodine, or chlorhexidine. Patients should be monitored regularly for signs of infection and unnecessary lines should be promptly removed. Noninfectious complications from parenteral nutrition include catheter occlusion, thrombosis, and breakage.
Compared to enteral nutrition, metabolic complications are more common in patients receiving parenteral nutrition. The most common one is hyperglycemia. Others include hypertriglyceridemia, steatosis, cholestasis, and essential fatty acid deficiency. To avoid these complications, it is important to provide an appropriate insulin regimen, avoid overfeeding, provide lipids in appropriate amounts, and provide enteral nutrition whenever possible. Metabolic labs should be routinely checked to adjust parenteral nutrition formulations as needed.
With the advancement of nutrition support, people who are otherwise unable to receive oral nutrition now have other options to receive adequate nutrition to combat their medical conditions. However, safe EN and PN practices based on evidence-based guidelines must be ensured to best ameliorate or prevent malnutrition.
What Is Nutrition Support Therapy? Accessed April 1, 2016.
Clogged Feeding Tubes: A Clinician’s Thorn. Accessed April 16, 2016.
McClave SA, Snider HL, Lowen CC, et al. Use of residual volume as a marker for enteral feeding intolerance: prospective blinded comparison with physical examination and radiographic findings. J Parenter Enteral Nutr. 1992;16:99-105.
ASPEN. Adult Nutrition Support Core Curriculum 2nd Edition. Maryland: American Society for Parenteral and Enteral Nutrition. 2012. Print.
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