Parenteral nutrition

Total parenteral nutrition (TPN) is the provision of intravenous nutrients to patients whose gastrointestinal (GI) tract is not functioning or cannot be accessed and to patients whose nutritional needs cannot be met with oral diets or enteral feeding. The patient receives a combination of nutrients- crystalline amino acids, dextrose, electrolytes, vitamins, minerals, trace elements and lipid/fat emulsion administered intravenously.

Once limited to critical care areas, TPN is now present on post surgical floors and medical units, when feeding by mouth is not possible, when a person's digestive system cannot absorb nutrients due to chronic disease, or, alternatively, if a person's nutritional requirements cannot be met by enteral feeding (tube feeding) and/or through oral diet.

WHAT IS TPN? Total parental nutrition (TPN) is the practice of nourishing a patient intravenously, bypassing the usual process of eating and digestion. It is a form of specialized nutrition, including amino acids, dextrose, fat emulsion, vitamins, minerals and trace elements given intravenously.

It is osmotically active and must be administered carefully to prevent trauma to the vascular portal of entry. It is administered intravenously and can be administered through a peripherally inserted central catheter (PICC), a central venous line (CVC) or a large peripheral line. Osmotically active means it is a solute that causes osmosis to occur. For instance, if a solution contains sucrose and the membrane is impermeable to sucrose,, water will move out of the cell and into the solution to dilute it. Hence the solution is hypertonic. Sucrose would be considered an osmotically active solution in this case because it induces osmosis of water across a membrane.

TPN is ALWAYS administered through an infusion pump. The sterile bags of nutrients are infused continuously through the pump over a 12 hour or 24 hour period to prevent vascular trauma and metabolic instability.

INDICATIONS FOR TPN ADMINISTRATION If there is intolerance to oral intake or enteral feeds and if the patient is NPO for an extended period of time. Short-term TPN (7 to 10 days) or long-term TPN (>10 days) is used to treat patients whose GI tract is not functioning or not accessible for various reasons.

Indications for TPN administration PHYSIOLOGICAL CONDITION - Non functional GI tract CLINICAL MANIFESTATION: Massive small bowel resection/ GI surgery Paralytic ileus Small bowel ileus (dilated bowel with air/fluid levels on CT scan) Intestinal obstruction Trauma to abdomen, head , neck Severe malabsorption Intolerance to enteral feeding (protracted nausea/vomiting) Bowel infarction/bowel ischemia Chemotherapy, radiation therapy, bone marrow transplant High output small bowel fistula >500ml/d Mechanical small bowel obstruction

Indications for TPN administration PHYSIOLOGICAL CONDITION – Extended Bowel Rest Inflammatory bowel disease exacerbation Severe diarrhea Moderate to severe pancreatitis Indications for TPN administration PHYSIOLOGICAL CONDITION – Preoperative TPN Preop bowel rest Treatment for comorbid severe malnutrition in patients with non-functioning GI tracts Severe catabolic patients when GI tract is non-useable for more than 3 to 5 days Catabolic Patient - A condition characterised by rapid weight loss and loss of fat and skeletal muscle mass, which may occur in a background of either an acute, self-limited disease—e.g., injury, infection—or a chronic condition—e.g.,diabetic ketoacidosis, multisystem organ failure, AIDS, advanced cancer, chemotherapy, radiation therapy

COMPOSITION OF TPN SOLUTIONS TPN is specialized nutrition including amino acids, dextrose, fat emulsions, vitamins, minerals and trace elements prepared in a sterile bag for intravenous administration. 2 components: amino acids/dextrose solution and lipid emulsion. TPN is ordered by the physician depending on the patient’s clinical history and current metabolic needs.

ACCESS ROUTES FOR TPN ADMINISTRATION TPN solutions must be carefully administered intravenously because it is osmotically active and can cause trauma to the vascular portal of entry. TPN is best administered through a large vein through a PICC or CVC. Peripheral IV is the last resort. The risk/benefit decision to use peripheral parenteral nutrition should include as many phlebitis-mitigating techniques as possible. TPN is NOT compatible with any other solutions and must be administered by itself. An infusion pump must be used to regulate the administration because it may lead to hypoglycemia

Parenteral nutrition solutions containing final concentrations exceeding 10% dextrose should be administered through a central vascular access device (CVAD) with the tip located in the central vasculature, preferably the superior vena cava right atrium junction for adults. INS Standards of Practice 2011, pg. S91

FOOD FOR THOUGHT Consult religious leaders about continuous infusion of TPN solution during fasting periods, i.e., Ramadan, Yom Kippur. Devout followers may insist on fasting. Follow agency policy and procedures when administering TPN.