Oct 22, 2017
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Parenteral Nutrition

IV nutrition doesn’t have to be scary or intimidating.  “Parenteral” means introduced otherwise than by way of the intestines by the Webster dictionary.    Parenteral Nutrition (PN) is the way to provide a steak, potato, and cheesecake into someone’s blood stream.   Due to new knowledge and technological advances, parental nutrition is used less often than previously and enteral nutrition is preferred in most cases.   Parenteral Nutrition (PN) is appropriate when: failed trial of small bowel enteral feeding, paralytic ileus, severe or  prolonged course pancreatitis, mesenteric ischemia (dead bowel), short gut syndrome, GI fistula that enteral access can’t be placed past, NPO Postop 5-10 days and not able to tolerate tube feeding (1).

Amino acids are used to provide protein in PN and provide 4 kcal per gram (2).  Amino acid solutions are available in concentrations ranging from 3% to 20%, so depending on your pharmacy, there is a potential to adjust the protein levels (2).   Dextrose is most common carb energy source in PN, providing 3.4kcal per gram.  IV fat emulsions are commercially available in concentrations of:  10% (1.1 kcal/ml), 20% (2.0 kcal/ml), and 30% (3.0 kcal/ml) (2).  Depending on facility’s pharmacy product choices, IV fat emulsions can hang separate from primary PN bag, piggy-backed, or included in the solution as a 3-in-1 solution.

To provide adequate fluid to meet the resident’s needs, the RD views the whole picture of all the intakes and outputs.   Parental residents are usually very ill and complex, and have other sources of output that need to be evaluated when estimating fluid needs.    Output from different sources usually needs to be replaced, remembering potential sources like wound vacs, diarrhea, ostomy output, chyle leaks, and fistula losses (2).   Typically, peripheral IVFs are used for repletion of fluid losses that are in addition to current volume received daily via PN.

With initial nutritional assessment, recognize resident at risk for complications, especially someone at high risk of refeeding syndrome.  Examples of high risk refeeding syndrome residents would be anorexia nervosa, chronic malnutrition, chronic alcoholism, prolonged fasting (3).   To combat this, correct electrolyte abnormalities before starting nutritional support, and advance PN slowly (2, 3).   Good goal is to avoid overfeeding.   Monitor labs closely, and replete electrolytes as needed.

Potential complications of parental nutrition can be: Essential Fatty Acid deficiency, high triglycerides, renal intolerance, refeeding syndrome, NASH/fatty liver disease, cholestasis, metabolic bone disease, high and low blood sugars (2, 3) .   Many of these can be managed with adjustment of the components of the PN and avoidance of overfeeding.

High triglycerides can usually be avoided with not overfeeding with dextrose, not rapidly infusing lipids (<110mg/kg/hr.), however sometimes, the resident can just be fat intolerant (2).  Prerenal azotemia (a cause before the kidneys) can be from dehydration, excess protein, or inadequate non-protein calories (2).  Intolerance to protein load will be noted by increase in BUN (2).  Hepatobiliary disorders usually occurs after longer term use.  Fatty liver caused primarily by overfeeding, is usually benign but can with long-term PN can progress to cirrhosis (2, 3).

“Cycling” PN daily can protect the liver from fatty infiltrates (2, 3).  Cycling means running the PN 8-12 hours per day, having time off of the IV infusion.   If needed for blood glucose management, the PN can be tapered on and off for cycling, i.e. running the PN at either ½ or ¾ goal rate for first 1-2 hours and off last 1-2hrs.  During of time of cycling and for when work to the goal of discontinuing the PN, monitor for symptoms of hypoglycemia, and have a prn order IV Dextrose 10% to run if needed (2).

Hypoglycemia, while using parental nutrition therapy, usually occurs with over dosage of insulin or abrupt discontinuation of PN.  To treat the hypoglycemia, run 10% Dextrose infusion, and/or stopping any source of insulin (2).  Follow up with frequent blood glucose checks (2).   The plan to avoid the hypoglycemia is to taper off PN with 1-2 hour off at half rate, adjusting the body to the decreased sugar influx.  If PN has to be stopped abruptly, run a dextrose fluid for another 1-2 hours, and monitor glucose levels for 1hr after it finishes (2).

Also, using IV nutrition means we are bypassing the GI tract and need to provide electrolytes and a MVI somehow.    Maintenance or therapeutic amounts of various electrolytes are added to PN formulations depending on resident’s requirements (2).  The physician, dietitian, and pharmacist work as a team to determine best choices for achieving stability in electrolytes and acid-base balance.  Multivitamin/ trace elements need to be part of standard PN, given daily, unless national shortages are present, then 3 times per week (2).   Refer to A.S.P.E.N. Drug shortage web page for specific recommendations: http://www.nutritioncare.org/Professional_Resources/Drug_Shortages_Update/.

 

 

 

 

References

  1. S.P.E.N. Board of Directors and The Clinical Guidelines Task Force. Guidelines for the use of parenteral and enteral nutrition in adult and pediatric patients. J Parenteral Enteral Nutr. 2002:26(1 suppl): 1SA-138SA.
  2. S.P.E.N. Parenteral Nutrition Handbook, 2nd Edition. Silver Spring, MD: American Society for Parenteral and Enteral Nutrition, 2014.
  3. S.P.E.N. Adult Nutrition Support Core Curriculum, 2nd Edition.  Silver Spring, MD: American Society for Parenteral and Enteral Nutrition, 2012.

 

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