PN Flashcards
What are the 2 ways of administering parenteral nutrition and what are the short names?
- peripheral vein (PPN)
- central vein (CPN, old way:TPN)
When would PN be advised?
• Pt unable to meet nutrition needs via EN or PO (either at all or in insufficient amounts)
Examples of Conditions Likely (but not 100%) to Require Parenteral Nutrition:
- Impaired absorption or loss of nutrients: E.g., Short bowel syndrome, high output intestinal fistula (more than 500 mL/d) (so the nutrients are lost through fistula or not absorbed due to short bowel)
- Mechanical bowel obstruction: E.g., Stenosis or strictures causing blockage of intestinal lumen (tube cannot be inserted due to blockage)
- Need to restrict oral or enteral intake: bowel rest • E.g., Severe pancreatitis, Ischemic bowel
- Motility disorders: E.g., Prolonged ileus
- Inability to achieve or maintain enteral access : E.g., Active gastrointestinal bleeding or vomiting-> tube will be displaced
What is ischemic bowel-
inadequate blood supply. to the bowel
what is an ileus
Ileus is the medical term for this lack of movement somewhere in the intestines that leads to a buildup and potential blockage of food material
what is stenosis
partial obstruction that results in a narrowing of the opening (lumen) of the intestine
what is an intestinal stricture
intestinal stricture is a narrowing in the intestine that makes it difficult for food to pass through
does pancreatitis = PN?
only in severe cases, and even then it is not a 100% diagnosis
What should always be done before administering PN?
Prior to initiating PN, conduct a full evaluation of the feasibility of using enteral nutrition (EN); reserve PN for clinical situations in which adequate EN is not an option.
When would PN be more preferable than EN?
Use PN in patients who are malnourished or at risk for malnutrition when a contraindication to EN exists or the patient does not tolerate adequate EN or lacks sufficient bowel function to maintain or restore nutrition status
How soon should we switch to PN?
- Initiate PN after 7 days for well-nourished, stable adult patients who have been unable to receive significant (50% or more of estimated requirements) oral or enteral nutrients
- Initiate PN within 3 to 5 days in those who are nutritionally- at-risk and unlikely to achieve desired oral intake or EN.
- Initiate PN as soon as is feasible for patients with baseline moderate or severe malnutrition in whom oral intake or EN is not possible or sufficient
- Delay the initiation of PN in a patient with severe metabolic instability until the patient’s condition has improved (has to be hemodynamically stable)
what are anti-emetic drugs
Antiemetic drugs are types of chemicals that help ease symptoms of nausea or vomiting
KG has an SGA score of C. She has a J-tube in situ and has been receiving 80ml of formula over 1 hr 6 x daily (intermittent schedule). Her feed has not been advanced due to c/o of pain, bloating and nausea. Proper placement of the tube has been confirmed. She has been placed on antiemetics and bowel function appears normal. It is now day 6 and her symptoms persist with the same feeding schedule. Could PN be appropriate?
Yes
Severely malnourished-> PN should be given as soon as possible
Have checked that everything is ok with EN
Ruled out constipation
Not enough PO
Is g-tube or j-tube better tolerated and can be used as a method of resolving EN intolerance?
j-tube
You’ve received a physician consult to start PN. Your patient has an enterocutaneous fistula with an average output of 180ml/d. Is PN appropriate?
No
Conditions to consider PN with fistula: high output intestinal fistula (more than 500 mL/d)
even if she had high-output fistula, we would still try EN first
LM is a 38-year-old woman with a history of pancreatitis. She is hospitalized for severe dehydration due to hyperemesis gravidarum. She is 11 weeks pregnant and has not been able to tolerate oral intake for the past 10 because of severe nausea and vomiting. Her current weight is 134 pounds; her pre-pregnancy weight was 140 pounds. Could PN appropriate?
Yes
- Constant vomiting-> tube can get misplaced
- PEG or PEJ is during pregnancy isn’t that great of an option because this is more long-term
she might be fine in the next trimester or the meds might start working
In PN, what is the name of the equipment that is used to administer nutrients?
Nutrients are provided via veins through a venous access device (VAD)
Which veins are used for PPN?
peripheral vein: veins and arteries not in the chest or abdomen (i.e. in the arms, hands, legs and feet)
What should we confirm with physician before starting PN?
confirm the location of administering PN
Can we use the same lumen of VAD for multiple purposes, including PN?
Dedicate 1 lumen of the VAD for PN administration when possible
Using the same lumen for PN and meds is fatal!
Long term PN: CPN or PPN?
CPN
What is the max osmolarity for PPN
Maintain an upper limit of 900 mOsm/L for the peripheral PN formulations.
PPN: When is it indicated?
Use peripheral PN only for short-term purposes, no more than 10–14 days, as supplemental PN or as a bridge therapy during transition periods, where oral intake or EN is suboptimal or clinical circumstances do not justify placing a CVAD.
what are the dangers of PPN?
PPN is delivered through a v small vein-> risk of thrombophlebitis caused by hyperosmolality of nutrient solutions
thrombophlebitis : inflammatory process that causes a blood clot to form and block one or more veins, usually in your legs.
How do we calculate osmolarity?
Multiply mOSm of components by grams present in PN solution
Which elements in PN have the highest osmolality?
AA and dextrose
Limitations of PPN
Peripheral veins cannot tolerate high fluid volumes or highly concentrated solutions:
• Lower solution concentration (lipids can be given at 20%, but usually AA concentration 3% and dextrose <10%)
Parenteral Nutrition- Contraindications to PPN
▪ Significant malnutrition
▪ Severe metabolic stress
▪ Large nutrient or electrolyte needs
- K+ is a strong vascular irritant (K is still put in IV to treat refeeding syndrome
▪ Fluid restriction
▪ Need for prolonged PN (> 2 weeks)
▪ Renal or liver dysfunction (depends on unit, ICU can medically
manage these diseases, other units likely need fluid restrictions)
Insulin and ON
Patients with type 1 and type 2 diabetes often require greater amounts of insulin from baseline during a PN infusion to lower blood sugar
Characteristic of CPN
▪ Long term (> 7 days to years)
▪ Can be hyperosmolar
▪ Can be used in fluid restricted pt
▪ The subclavian or jugular vein is catheterized
Why is CPN more “forgiving”?
since central vein is much bigger and it has more rapid blood flow, the solution will be diluted much faster-> lower risk of complications
which type of PN permits for easier administration of K?
CPN
When might we need to administer hyperosmolar PN solutions?
- fluid restricted patient
- trying to meet patient’s high nutrient
Methods of access/catheters for CPN
- PICC = peripherally inserted central catheter; Catheter implanted into arm then threaded into subclavian vein with the tip inserted in the superior vena cava)
- CVC= central venous catheter (aka central line)
Give examples of CVC + their descriptions
• Tunneled catheters : multiple lines- each for different purpose
• Implantable ports: very invasive,
available for long time.
when can CPN provide adequate energy and protein?
“ CPN provides complete nutrition in a reasonable fluid volume and may be concentrated to provide adequate energy and protein for those patients requiring fluid restriction.
Patients considered for PPN must meet 2 criteria:
Patients considered for PPN must meet 2 criteria:
(1) they must have good peripheral venous access, and (2) they should be able to tolerate large volumes of fluid (2.5 to 3 L/d).
what is phlebitis?
inflammation of the vein
Contraindications to Peripheral Parenteral Nutrition”
- Significant malnutrition
- Severe metabolic stress
- Large nutrient or electrolyte needs (potassium is a strong vascular irritant)
- Fluid restriction
- Need for prolonged parenteral nutrition (>2 weeks)
- Renal or liver compromise
What are all the potential components of PN?
▪ Carbohydrate (dextrose) ▪ Intravenous Fat Emulsions (IVFE or ILE) ▪ Proteins (amino acids) ▪ Additives - Electrolytes - Vitamins - Trace elements - Insulin
What are the 2 types of nutrient solutions for PN?
• 2-in-1 (carb + aa) + lipid (separate) - Aka traditional
• 3-in-1 (carb + fat + aa) - Aka total nutrient
admixture (TNA)
what is automated compounding?
device (ACD) allows for individualized formulas that can be adjusted daily
Describe the setup of 2 in 1 PN formulation
- Dex, AA, electrolytes, vits/mins in 1 bag
- Lipids in a separate bag • bag as “piggyback” infusion (bag hang time max. 12 hr)
- There are 2 bags hanged up that are eventually mixed together via a Y-connector
What is the reason for separating lipids?
they are unstable
What are the pros and cons of 2-in-1
cons:
- bag hang time max. 12 hr (for sanitary reasons)
- since fat has to be infused during a shorter amount of time, a lot of fat has to be infused at once-> can lead to high blood TG and fatty liver
pros:
- bags are clear-> can see if precipitate forms e.g. with patient who needs a lot of electrolytes (they can sometimes precipitate)
- more stable as lipids are separate
Describe the setup of 3 in 1 PN formulation
Dextrose, AA, lipids and additives all together in one bag
Pros and cons of 3-in-1
Pros:
- Can be administered over 24 hr
- less effort (no mixing)
- less tubes
Cons:
- cloudy due to liquids-> precipitate cannot be observed
What is the “format” of protein in PN
individual AA
What are the concentrations available for protein in PN? What do those concentrations mean?
Commercial concentrations = 3.5% to 20%
• 3.5 % means 3.5 grams of AA in 100 ml of solution
• (3.5g solute in 100ml of diluent or 35g/L)
• 20% means 20 grams of AA in 100 ml of solution (200g/L)
What is the most common protein solution
travasol 10%
What are the kcal per 1g of AA soln?
4kcal per 1g
What is the format of CHOs in PN? What are the kcals?
–Always given as dextrose monohydrate
–Provides 3.4kcal per 1g dextrose
What are the concentrations available for CHOs in PN? What is their meaning?
Commercially available in 5, 10, 50 and 70%
concentrations
• 5% = 5 gm dex/100 ml solution
• 5% is referred to as D5W (Dextrose 5%)
How many calories does 5% dextrose infused at 75ml/hr provide?
306
How many calories does 5% dextrose infused at 75ml/hr provide?
306kcal
What is the recommended/max glucose infusion rate in PN?
- Clinical studies suggest that carbohydrate administration via PN greater than 4–5 mg/kg/min (GIR) exceeds the mean oxidation rate of glucose, giving rise to significant hyperglycemia, lipogenesis, and fatty liver infiltration
- Aim to keep GIR <5 and preferably around 3mg/kg/min
How to calculate glucose infusion rate?How to easly do it
Units for GIR are mg/kg/min
thus
GIR= total milligrams per 24h / patient’s weight*100mg/1440 min
24h*60min= 1440min
48 kg patient receiving 10% dextrose at 95ml/hr. What is the GIR?
3.3
What are the names for lipids solution in PN?
ILE/IVFE
injectable lipid emulsion/Intravenous fat emulsion
What are the old and new sources of lipids for PN?
Old option: soybean oil (Intralipid)
Newer options contain MCTs, fish oils and olive oil
What are the possible complications of lipid infusion?
Hyperlipidemia and impaired immune response, fat overload syndrome
What are the max and recommended doses (aka safe checks) for lipid infusion?
- Max dose:<2.5g/kg/d
* Aim for 1g/kg/d and/or no more than 30% of kcal as lipids
What are the calories for lipids in PN?
10% = 1.1 kcal/ml, 20% = 2 kcal/ml
10% Intralipid caloric value per gram = 11kcal/g ; 20% = 10kcal/g
What are the available concentrations for lipids and which ones should we aim for?
Avail in 10, 20, 30% concentrations – 30% rarely used
What should we remember about Propofol?
Propofol (sedative) used in ICU is a lipid-based solution providing 1.1kcal/ml (make sure you account for this added energy)
sometimes so much Propofol is given that you dont even need to give extra lipids
What should we remember about allergies with PN?
Consider allergies to any lipid component such as eggs, soy, fish.
How to avoid essential FA deficiency with PN?
- Estimated 2-4% of energy from linoleic acid recommended
- EFAD increases after 20 days if no sources of EFA in PN
- Typically lipids are provided 2 x weekly or daily • ~250ml of 20% or 500ml of 10% soy-based ILE
How many kcal does 20% ILE
provide at 75ml/hr?
3600
What are electrolyte amounts that should be added to PN are based on?
- Requirements are based on body weight, existing electrolyte deficiencies, ongoing electrolyte losses, and changes in organ function
- Requirements inextricably linked with amount of macronutrients: electrolyte recommended Intake in PN amounts are given as ranges; aim for upper limit of the range for someone who has high macronutrient requirements
Which 2 electrolytes have their recommended intake in PN given as mmol/kg? What are the units for other electrolytes?
Potassium and Sodium
the other electrolytes are given just as mmol
How are vitamins/minerals administered in PN
Are preformulated in vials
It’s the number of vials to give that is calculated
Why do requirements for vitamins/minerals differ from DRIs for PN?
requirements are different from DRIs due to different bioavailabilities
recommendation for PN initiation
PN initiated at half estimated energy needs, or 150- 200g dextrose, for first 24 hrs
How is PN usually administered in terms of times
In hospital usually continuous (24hrs)- usually not stopped over 24h (unlike EN)
At home can cycle (e.g., overnight)
recommendation for PN termination
• To discontinue, gradual decrease in infusion rate until transition to oral or enteral nutrition meets minimal nutrient needs
• E.g., once meeting 50% energy PO/EN (ESPEN, surgery)
• Taper off: Cut rate by 50% for 1-2 hours then D/C. Should not be stopped abruptly!
is infusion is stopped rapidly, their is a high chance of developing hypoglycemia
• Emergent stop: Infuse D10W at rate of at least 50ml/hr for 1-2h
• Check BG for at least first 30min
· Catheter often remains for medications
Fluid needs, PN and IV
if you have a patient with excessive losses or you can meet their goals with PN-> would request extra IV
usually you can meet fluid need with PN-> would want to discontinue IV
just make sure that with PN and IV you are not over-hydrating a person
What are the Standard monitoring protocols for PN aka what should u always monitor?
- Intake and output, hydration assessment
- Hyperglycemia
- Test 3-4 x per day
- Daily measures for electrolytes, BUN, creatinine
- Lipids(weekly if abnormal)
- If long-term: vits/mins q 3-6mos; more often if abnormal
- Liver enzymes weekly
+ monitor IV site
What are the possible PN complications?
- GI complication, especially if bowel at complete rest. Not caused by PN, caused by the absence of substances on GI
so nothing will stimulate the bile - Infection (check temperature, WBC trends)
- refeeding syndrome, overfeeding
SHort term PN complications
▪ Hyperglycemia: optimize glucose infusion rate. if still develops hyperglycemia-> lower the rate
▪ Azotemia:
high BUN + creatine; mb due to excessive protein
usually due to not getting enough calories from non-protein sources
aka not given enough carbs and fat or due to dehydration
▪ Refeeding Syndrome
Long term PN complications
▪ Vascular access sepsis
▪ Hypertriglyceridemia
o d/t dextrose overfeeding or rapid ILE infusion
▪ Hepatobiliary complications
o Steatosis, cholestasis, gallstones related to resting gut (no stimulation)
▪ Metabolic bone disease
when should we look out for refeeding syndrome?
watch out for it during the first 2-5 days of initiating nutrition support
define refeeding syndrome
a measurable reduction in levels of 1 or any combination of phosphorus, potassium, and/or magnesium, or the manifestation of thiamin deficiency, developing shortly (hours to days) after initiation of calorie provision to an individual who has been exposed to a substantial period of undernourishment
which electrolytes to look out for when there is a risk of refeeding syndrome
- magnesium
- phosphate
- calcium
- thiamine
Refeeding: Treatment/Prevention
• Check ASPEN refeeding guidelines
1. First correct electrolyte imbalance and supplement thiamin
• Check serum potassium, magnesium, and phosphorus before initiation of nutrition.
• “In patients with moderate to high risk of RS with low electrolyte levels, holding the initiation or increase of calories until electrolytes are supplemented and/or normalized should be considered.”
• “Supplement thiamin 100 mg before feeding or before initiating dextrose- containing IV fluids in patients at risk”
- Start low and advance slow
• “Initiate with 100–150 g of dextrose or 10–20 kcal/kg for the first 24 hours;
advance by 33% of goal every 1 to 2 days. This includes enteral as well as parenteral glucose”
if levels drop- do not stop, but do not advance either - Advance only if showing signs of tolerance
• “Initiation of or increasing calories should be delayed in patients with severely
low phosphorus, potassium, or magnesium levels until corrected.”
• “Monitor P, K, Mg every 12 hours for the first 3 days in high-risk patients. May
be more frequent based on clinical picture”
which supplement should always be given if there is a risk of refeeding syndrome?
Thiamin