total parenteral nutrition

(TPN, total nutrient admixture)

A method of feeding that bypasses the gastrointestinal tract. Fluids are given into a vein by a needle or catheter to provide most of the nutrients the body needs.
It is used for patients who require nutrition therapy but cannot or should not receive feedings or fluids by enteral feeding.

(Comparison)
• enteral feeding: Intake of food via the gastrointestinal (GI) tract, that is composed of the mouth, esophagus, stomach, and intestines.
• parenteral nutrition: Injection of fluids given into a vein.

(Ways of administeration)
• central venous catheter: Through a large vein that goes directly to the heart.
• peripherally-inserted central catheter (PICC) line: Through a vein in the arm and passed through to the larger veins near the heart. Used for long-term IV feedings.
• midline catheter tube: Ends in a vein below the armpit.
• peripheral parenteral nutrition (PPN): Regarded as a safe and effective alternative to central vein administration of nutrients for many patients. It avoids the risks of central venous catheterization, simplifies nursing care, reduces cost and may prevent delay in the initiation of nutritional support.
• Sites for venous access in young children include the hands, feet, forearms, and scalp. For babies, umbilical vein may be also used.

(Fluid contents)
• glucose (sugars)
• electrolytes (salts)
• amino acids (proteins)
• lipids (fats)
• vitamins
• minerals

(Examples of patients and diseases)
• sick or premature newborns
• geriatric patients
• cancer patients
• short bowel syndrome
• small bowel obstruction
• active gastrointestinal bleeding
• anorexia
• high-output enterocutaneous fistulae

(Complications)
• infection: Through catheter, pneumothorax, accidental arterial puncture, and catheter-related sepsis. This can be related to hyperglycemia. Death usually results from septic shock.
• blood clots: Death can result from pulmonary embolism. Patients may receive a thrombolytic therapy to avoid it.
• fatty liver and liver failure: Due to using linoleic acid (an omega-6 fatty acid component of soybean oil) as a major source of calories.
• cholecystitis: Due to complete disuse of the gastrointestinal tract, which may result in bile stasis in the gallbladder.
• metabolic complications: Refeeding syndrome characterised by hypokalemia, hypophosphatemia, and hypomagnesemia. Hyperglycemia is common at the start of therapy, but can be treated with insulin added to the solution.
• hunger
• gut atrophy
• hypersensitivity