Medical nutrition therapy: Parenteral nutrition ** Flashcards
It’s the therapy provided through intravenous administration of nutrients such as amino acids, glucose, lipids, electrolytes, vitamins and trace elements:
Parenteral nutrition (PN).
How is PN classified?
- Total parenteral nutrition (TPN) or exclusive parenteral nutrition.
- Supplemental parenteral nutrition (SPN) or partial parenteral nutrition or complementary parenteral nutrition.
- Home parenteral nutrition.
What are the indications for PN?
- When it is not possible to administer EN because the gut is not functioning: Impaired absorption of nutrients, mechanical bowel obstruction, motility disorders, need for “bowel rest”.
- When the gut is not accessible.
- When tube feeding is not safe.
- When enteral or oral feeding is not reaching the nutritional target.
What are the contraindications for PN?
- Functioning GI tract.
- Treatment anticipated for < 5 days in patients without severe malnutrition.
- Inability to obtain venous access.
What are the main components of PN?
- Amino acid solution.
- Glucose (dextrose) solution.
- Lipid emulsion.
- Water for injection.
- Electrolyte solution.
- Vitamin and trace element PN components.
What are the three main methods by which PN can be administered?
- Central parenteral nutrition.
- Peripheral parenteral nutrition.
- Via an arteriovenous shunt.
Which method of PN administration is done via a catheter with tip located in a central vein, usually at the junction of the superior vena cava and right atrium?
Central PN.
Which method of PN administration is done via a cannula or catheter inserted into a peripheral vein, usually from the forearm, that is commonly used in patients who require therapy for a short duration, usually for several weeks to a few months?
Peripheral PN.
Which method of PN administration is applied to patients in whom central catheterization is not possible?
PN via an arteriovenous shunt.
Which nutritional product for PN contains all macronutrients and electrolytes in three separate compartments, in which the substrates are mixed together immediately prior to IV application by breaking the separation seals between the bag chambers?
Three chamber bag.
Which nutritional product for PN cointains a solution in which amino acids and glucose (no lipid emulsion) are combined in a single infusate, along with electrolytes, vitamins and trace elements as required?
Two Chamber bag:
- Bag/two-in-one (lipid-free) PN bag (usually industry manufactured).
- Two-in-one (mainly pharmacy provided) PN infusate.
What are the most common complications associated with catheter placement in PN?
Infection, clogging (occlusion), and breakage.
What is the most serious complication of central venous catheters?
Infection
In which type of medical nutrition therapy is the refeeding syndrome more common?
In enteral nutrition.
What are the three main steps to take in the prevention of refeeding syndrome?
- Severely malnourished patients should initially receive only 20 - 30% of their energy requirements, building up to full intake over several days.
- This should be combined with a high intake of phosphate and potassium, with frequent monitoring of blood levels.
- A bolus injection of 100 mg of thiamine should also be given and a high level of provision continued.
How can we calculate the amount of glucose that each patient can utilize?
< 5 mg/kg of body weight.
What is the timeframe for beginning PN in well-nourished, stable adult patients who have been unable to receive significant oral or enteral nutrients?
Initiate PN after 7 days.
What is the timeframe for beginning PN in those who are nutritionally-at-risk and unlikely to achieve desired oral intake or EN?
Initiate PN within 3-5 days.
What is the timeframe for beginning PN in patients with baseline moderate or severe malnutrition in whom oral intake or EN is not possible or sufficient?
Initiate PN as soon as is feasible.
