Patients who are unable to tolerate enteral feedings can be given an intravenous solution containing fat emulsions, dextrose, amino acids, vitamins, and minerals. This solution can be modified to meet the individual nutritional needs of each patient.
Blood glucose levels should be monitored closely in patients receiving TPN. Solutions containing too much dextrose may lead to hyperglycemia. Anticipate that sliding insulin may be ordered to keep blood glucose level within normal range.
The amount of lipids in a TPN solution should be determined based on a patient’s metabolic needs, in order to prevent hyperlipidemia. Keep in mind, administration of fat emulsions or lipids is contraindicated in patients with preexisting hyperlipidemia. Lipid-free TPN may be administered the first 3-5 days in critical patients to avoid onset of proinflammatory conditions, which can occur with omega-6 fatty acids.
Refeeding syndrome can occur in chronically malnourished patients who are started on nutritional therapy. When nutritional support is delivered too quickly, there is a sudden increase in phosphate demand, causing phosphate to be drawn out of the blood. Hypophosphatemia can cause dysrhythmias, respiratory depression, and changes in mental status. Fluid retention is also characteristic of refeeding syndrome, along with other electrolytes imbalances (hypokalemia, hypomagnesemia).
When administered too rapidly, TPN solutions containing lipids may cause nausea, vomiting, and in some cases elevated temperature. An infusion pump must be used to ensure that the solution infuses slowly, at a constant rate.
When administered too rapidly, TPN solutions containing lipids may cause nausea and vomiting. Hyperosmolar diuresis can also result from an infusion that is too rapid, and can lead to dehydration, hypovolemic shock, seizures, coma, and death. Do not increase rate of TPN in an attempt to catch up, if the infusion falls behind schedule.
TPN should be administered through a large central vein to prevent complications such as thrombophlebitis. This condition occurs when there is irritation of the vein caused by a clot. An infusion pump must also be used when administering TPN, to ensure that the solution infuses slowly, at a constant rate. Keep in mind that central line parenteral nutrition and peripheral parenteral nutrition (peripheral large venous access) will differ in tonicity, because peripheral veins cannot tolerate the hypertonicity of central line TPN solutions due to problems associated with irritation and thrombophlebitis and fluid overload.
It is important to remember that additional medications should not be added to the TPN solution, nor should they be administered through the line containing TPN. An IV filter should be used with all TPN infusions.
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