Lecture 20 Parenteral Nutrition Flashcards
What is parenteral nutrition?
IV admin of nutrients (aa, dextrose, lipids, fluid, electrolytes, vitamins and minerals)
2 categories: peripheral and total (central) (given via superior vena cava)
What are some indications for parenteral nutrition?
when enteral is contra or underlying intestinal tract disease ⇒ small bowel obstruction, massive small bowel resection, intractable D/V, persistent signs of gut dysmotility, GI tract not accessible, enteral access has been lost or can’t be obtained such as in facial injuries/head and neck cancer, severe esophageal varices
also IBD not responding to med tx, intensive chemo/severe mucositis, major surgery/stress, trauma requiring repeated surgeries
What are contraindications for parenteral nutrition?
functional GI tract, previously well nourished adult, minimal stress, recovery of GIT expected in <7 days, prognosis doesn’t warrant aggressive tx, risks > benefits, no venous access
hat are different central access devices for parenteral nutrition?
PICC (Peripherally Inserted Central Catheter): inserted into peripheral vein and wired into central venous system into superior vena cava, stays in place for up to 1 year for extended tx
Short-Term Non-Tunneled: triple or double lumen placed into jugular, subclavian, or femoral vessel
for multiple access needs in acute care, 4-6 weeks only; high complication risk
Long-Term Tunneled: ex. Broviac, long term/recurring tx, single and multilumen, possible decreased risk of catheter infection, easier to care for and repair; decreased risk of dislodgement
Implanted Catheter: catheter attached to disk with self sealing port, advantages include minimal changes to body image, doesn’t require routine site care when not in use, ideal for infrequent but chronic IV tx
What is peripheral parenteral nutrition?
requires low conc of macronutrients in large fluid volumes, osmolarity of <900 mOsm/L
undesirable for fluid restricted pt
typically used for short periods of time, pt must have good peripheral access, high risk of line thrombosis
What is standardized/premixed parenteral nutrition?
industry compounded multi-chamber bags available with and without lipid injectable solution and electrolytes, cost effective and improved pt safety, not appropriate for all pt and requires full assessment to determine suitability
What is compounded parenteral nutrition?
contain aas, dextrose, electrolytes, vitamins, minerals (with or without lipids)
it should meet individual nutrient requirements of specific pt
come in 3L bags
What are parenteral nutrition bags composed of?
macros: carbs in form of dextrose, aas, lipid, water
micros: electrolytes, vitamins and trace elements
What makes up the carbohydrate component of parenteral nutrition?
caloric density of dextrose is 3.4 kcals/gram,, 2.5%-70% solutions available
higher dextrose conc are for central PN
acidic solutions
What makes up the protein component of parenteral nutrition?
crystalline aas provide 4 kcals/gram
2.5-20% solutions available
may also contain combos of electrolytes and/or buffers (ex. acetate)
generally balanced between essential, semi-essential, and non-essential aas
What makes up the lipid component of parenteral nutrition?
non-carb energy source
provides essential fatty acids, energy dense, egg yolk phospholipid as an emulsifier and glycerin to provide isotonicity
contains small amounts of Vitamin E and K
pH range of 6-9
What makes up the micronutrient component of parenteral nutrition?
Electrolytes: pre-added in specific amounts to stock formulas or individually added to pt needs
includes Na+, K+, Mg2+, PO43-, Ca2+
acetate and chloride added/adjusted to maintain acid-base
Multivitamins: some combos and some single vitamins available, fat and water soluble
no Vitamin K is contained in multivitamin (add separately if indicated)
Trace Elements: common formulas have Zn, Cu, Cr, Se, Mn
also available in singular form
different combos and conc for peds and adults
iron dextran available for addition if required
What are some examples of Schedule 1 drugs that may be added to PNs?
H2RAs: can add for stress ulcer tx, don’t add if already on PPI IV or PO
Vitamin K (Phytonadione): standard weekly dose 10 mg, additional can be given if deficient, potential contra ⇒ history of DVT/clots/pulmonary emboli, warfarin use
Insulin: ONLY Regular insulin can be added to PN
How can parenteral nutrition be administered?
Continuous: infused over 24 hours (lipids 12 hours if run separately), typically for initiation and metabolically unstable pt
Cycled: admin over less than 24 hours, typically 12 hours, pt must be hemodynamically stable, advantages are improved liver clearance, assists with pt mobilization
What are the complications that can arise from parenteral nutrition?
Mechanical: placement related events, thrombosis, thrombophlebitis
Metabolic: short term and long term complications include: electrolyte imbalances, hyper/hypoglycemia, fluid imbalances, cholestatic liver disease, metabolic bone disease
Infectious (catheter related): attributed mortality of 12-25%, all central venous catheters are at risk, infections can originate from endogenous skin flora, contamination of catheter, seeding of device from another site, contamination of IV fluid/PN
dextrose and lipid serve as ideal mediums for bugs
