PN Practice Questions Flashcards
What is the optimal nutrition support for a malnourished patient when EN is not feasible for a prolonged period? A) Central Parenteral Nutrition B) Nasogastric enteral tube feedings C) Postpyloric enteral tube feedings D) Peripheral parenteral nutrition
A
The benefits of CPN are most closely related with patients with malnutrition
In which patient or condition treatment could PN elicit an improved patient outcome?
A) Cancer chemotherapy
B) Pre-op care of Sx patients with upper GI cancer
C) Allogenic bone marrow transplant
D) Critical illness
B
When does PN provide improved outcomes within the context of pre-op care of Sx patients with upper GI cancer?
When it is initiated 7-days before surgery
CPN is contraindicated in which of the following conditions? A) DNR status B) Peritonitis C) Intestinal Hemorrhage D) High-output fistulas
A
Comfort measures only
PN should be discontinued when which of the following criteria are met?
A) A clear liquid diet is ordered
B) Tube feeding is initiated at 10% of goal rate
C) Solid food is tolerated by mouth
D) Advancement to regular diet is poorly tolerated
C
As the goal of PN therapy is to maintain the nutritional status of patient until some form of EN is tolerated.
When is PN tapered?
When EN can be used, where it will slowly increase in proportion to PN
When is PN discontinued?
- Solid food tolerated orally
- DNR status
What are the three ways the PN can be prepared?
1) Lipid injectable emulsions (LIE)
2) TNA
3) 2 in 1 solution
What is the 2 in 1 solution?
Contains all the necessary IV macro and micronutrients, in the same container, without ILE which may be infused separately
PN is always ___ to body fluids
hypertonic
What is the osmolality of PN dependant on?
- Dextrose
- AA
- Electrolyte content
What is TPN?
Total parenteral nutrition, usually associated with CPN as the entire needs of the patient may be delivered by this route
Where is TPN administered? Why?
Superior vena cava adjacent to the right atrium, as the rate of blood flow is the higher and will rapidly dilute the hypertonic PN
What has a higher concentration of nutrient components, PPN or TPN?
TPN
PPN must be lower for peripheral venous administration
Why is PPN usually an undesirable choice for those with fluid restrictions?
Concentrating the solution to meet their fluid req. will result in hyperosmolar solution, which is likely not suitable for peripheral administration
What are the criteria patients must meet in order for PPN to be indicated?
1) Good peripheral vein access
2) They should be able to tolerate large volumes of fluid (2.5 - 3L/days)
Time limit for PPN?
At least 5 days, but no longer than 12 days
How may the energy density of PPN be increased without increasing osmolality?
ILE’s, may also increase peripheral vein tolerance of PPN
Contraindications to PPN?(SSL-FNR)
- Significant malnutrition
- Severe metabolic stress
- Large nutrient or electrolyte needs
- Fluid restriction
- Need for prolonged PN > 2 weeks
- Renal or liver compromise
What is permissive underfeeding?
Used in the critically-ill patient, who do not tolerate PN well.
-Minimize complications of PN by feeding 80% of energy req. until patients condition has improved
What is hypocaloric feeding?
- Used in both EN and PN for obese patients (BMI >30)
- Meet pro req. but reduce energy
- May also mitigate complications to PN while improving nitrogen balance
What is supplemental PN?
Minimize the energy deficit that accumulates during periods of no nutrition or undernutrition
Expert opinion suggests that wound healing will be impaired if PN is not started within _____ of post-op for indicated patients
5-10 days
How is PN indicated in pancreatitis?
It is not
-Important to maintain GI integrity with EN to improve outcomes
Patients at the highest risk of adverse post-surgical outcomes are those with low _____ at baseline
visceral proteins
What is critically illness characterized by?
A catabolic state that is generally the result of systemic inflammatory response to infectious or traumatic assault
Why is gut failure common in the critically ill?
Due to preferential blood supply to vital organs
Critically ill patients indicated for PN will meet what 3 criteria?
1) Are malnourished at baseline
2) Will not reliably ingest or absorb significant amounts of EN for a period greater than 7-10 days
3) Have been adequately resuscitated from any hemodynamic compromise
PN in cancer patients?
Associated with increased complications and infections if receiving chemo or radiotherapy
When is PN Ok to advance?
- Stable BP,pulse and resp.rate
- Normal phosphorous, potassium and glucose concentrations
What is a best practice prior to advancing PN rate?
Control the patients blood glucose
Which of the following may increase the risk of phlebitis with peripherally administered PPN?
A) Osmolarity equal or less than 900 mOsm/L
B) Potassium 100 mEq/L
C) Calcium <5 mEq/L
D) Addition of heparin to the PPN
B
Potassium can be irritating in the veins, preferably less than 40 mEq/L should be administered, all other choices listed actually may decrease phlebitis risk
What is phlebitis?
Inflammation of the vein, can cause pain and swelling
What is the smallest pore size of a filter recommended for TNA? A) 0.22 um B) 0.5 um C) 1.2 um D) 5 um
C
Is the 1.2 um filter a sterilizing filtre?
No, but will remove large micro-organisms and large particles which may otherwise lodge in the pulmonary capillaries if passed through
When is a 0.22 um filter used?
Often in 2-1 dextrose and amino acid PN, and it does qualify as a sterilizing filter
How big are fat particles? Which PN filters will occlude the use of ILE?
- Fat particles between 0.1 and 1.0 um
- -0.22 and 0.5 um filters are occluded, or the emulsion may be destabilized if used with these filters
Which of the following will increase the solubility of calcium and phosphate within a PN formulation? A) Use of calcium as the chloride salt B) Use of phosphate as the sodium salt C) Increased amino acid concentration D) Increased temperature
C
The higher the concentration of AA, the less likely precipitation is to occur.
The higher the concentration of AA, the less likely precipitation is to occur. Explain how
Amino acids can form soluble complexes with calcium, which will reduce the effective concentrations of free calcium available to form insoluble precipitates with phosphorous ions.
Why is calcium gluconate preferable over calcium chloride?
Calcium chloride is more dissociated that calcium gluconate, making the risk of precipitation with phosphate higher.
What is more likely to occur at higher temperatures?
-Precipitation, as warmer temperatures will encourage the dissociation of of calcium salts, thus promoting the availability of ions to form insoluble complexes with phosphate
According to the ASPEN guidelines, the amount of dextrose used in the preparation of PN formula is required to appear on the label as:
A) The percentage of original concentration and volume (i.e. dextrose 50% water, 500 ml)
B) The percentage of final concentration after admixture (i.e. dextrose 25%)
C) Grams per liter of PN admixed (i.e. dextrose 250 g/L)
D) Grams per day (i.e dextrose, 250 g/day)
D
Most consistent and supports the 24-hour nutrient infusions, requires the least amount of calculations.
Most common CHO source in PN? kcal/g?
- Dextrose
- 3.4 kcal/g
- Acidic and hyperosmolar
Most common protein source in PN? kcal/g?
- Crystalline AA
- 4 kcal/g
Discuss the modified PN AA formulation for those with hepatic encephalopathy
-Increased branched chain amino acids
-Decreased aromatic amino acids
As their altered metabolism often results in higher serum amounts of AAA, which is taken up by the brain, act a neurotransmitters and may cause altered mental status
Modified PN for renal failure?
-Mostly essential AAs
ILE 20% formulation?
Provides 2kcal/ml
ILE 30% formulation?
Provides 2.9-3 kcal/ml
What is ILE 30% approved for?
Compounding of a 3-1 mixture, and not for direct IV administration
ILE products using a 50:50 mix of soybean and safflower oil will contain _____ as much omega-3 FA as an ILE using 100% soybean oil
half
What is Smoflipid?
ILE containing Soybean (S), MCT (M), Olive (O) and Fish (F) oils to be higher in omega-3 FA
When is Smoflipid contraindicated?
For patients with allergens or hypersensitivities to soy, egg, peanut or fish protein
What emulsifer is used in ILEs?
egg-phospholipid (caution with egg sensitivities and allergies)
What should the ILE infusion rate not exceed? What should the daily dose not exceed?
- 0.11 g/kg/hr
- 60% of E requirements or 2.5 g/kg/day
What may exceeding the ILE infusion rate result in?
- HyperTG
- Infectious complications
- Fat overload syndrome
What is fat overload syndrome?
Characterized by headaches, seizures, fevers, jaundice, abdominal pain, resp distress, pancytopenia and shock
What is the issue with Omega-3 and Omega-6 FA ration in PN?
We want to have enough Omega-3s to promote anti-inflammatory functions, but enough Omega-6s to avoid a EFA deficiency
Preferred form of calcium PN salt?
Calcium gluconate
Preferred form of magnesium PN salt?
Magnesium sulfate
Preferred form of iron in PN?
Iron dextran
-Should only be considered in dextrose-amino formulas because ILE formulas are disrupted by iron
Two nutrient with special consideration in PN?
- Glutamine
- Carnitine
Glutamine in PN?
Has been considered for it’s role with intestinal integrity and protein synthesis during stress states, however no longer recommended for ICU as no benefit is shown
Carnitine in PN?
Carnitine is required for proper transport of LTC into the matrix of the mitochondria for B-oxidation. Sometimes added in IV formulations, but MCT oil may be preferable
What is the most appropriate strategy to provide calcium to a patient receiving PN in the event of a IV calcium gluconate shortage?
- Evaluate for signs relating to low calcium concentrations (tetany, CNS, CVD issues)
- Evaluate serum levels of calcium and ionized calcium, correct calcium with albumin levels
- If calcium supplementation necessary, administer CaCl separately from PN formulation, using a different catheter.
What are the two ways to prepare for the administration of PN?
1) Traditional dextrose-AA formulation (2-in-1)
2) TNA system (3-in-1, or all-in-one)
What is the 2-in-one formulation?
Incorporates dextrose and AA alongside vitamins, minerals, electrolytes and trace elements. ILE will be administered separately
What is the TNA or the 3-in-1 formulation
incorporates ILE with AA, dextrose and all required micronutrients all at once
Considerations for osmolarity for PPN?
-<900 mOsm/L
Considerations for calcium and potassium in PPN?
- Should be kept low
- Calcium <5 mEq/L
- Potassium <40 mEq/L
Considerations of ILE in PPN?
-Give daily to provide adequate energy and decrease osmolality
Considerations of TNA in PPN?
Deliver dextrose (10%) and AA (4%) at optimal concentrations to prevent lipid destabilization from divalent cations, but may have difficulties in adhering to the osmolarity restrictions in PPN
What may reduce risk of thrombophlebitis ?
Addition of heparin and/or small amounts of hydrocortisone to PPN
(T/F) all vitamins and minerals are found in SCAPN
False, must be injected because these micronutrients may destabilize the product if added prior to 24 hours of administration
What is stability with respect to PN?
Degradation of nutritional components which changes their original characteristics (i.e. maillard rxn)
What is compatibility with respect to PN?
Involved the formation of precipitates (crystalline matter or the seperation of oil and water)
What is the issue of administering ILE with iron dextran?
This trication will compromise compatibility of ILE, resulting in phase seperation
-Perhaps administer with 2-in-1
What may change the electric surface charge on the fat droplets in ILE, resulting in fat globules?
- Changes in pH (stable between 6 and 9)
- Additions of electrolyte salts
When there is phase-seperation in ILE, how may the bag appear?
-Yellow oil streaks
-Amber oil layer on top of admixture bag
Unsafe for patient administration
What is the most critical factor influencing the pH of a PN formulation?
-Crystalline amino acid solution used for compounding
How should TNA be compounded?
- Combine dextrose with the AA solution first, as the AA will buffer the acidity of the dextrose
- Add this solution to the ILE
When may TNA stability be compromised?
When final concentrations are less than: -4% AA -10% dextrose -2% ILE This will cause the larger fat globules, which occurs before the 30-hour use before date assignment
TNA should be used with ____ or ____ as PPN formulations
- Extreme caution
- Not at all
Which form of calcium phosphate is the greatest threat?
Dibasic calcium phosphate
-More likely to precipitate from a increase in pH
How can we reduce the likelihood of dibasic calcium phosphate the precipitate? What is the consequence if in ILE?
- lower the pH of the PN formulary, and lower the concentration of calcium and phosphate ions administered
- Lowe pH is suboptimal in ILE, thus administer separately (i.e. 2-in-1)
What filter is OK for removing calcium phosphorous precipitates?
-5 um
NOT a replacement for good compounding practices intended to prevent precipitation in the first place
0.22 um filtres?
- Can remove pathogenic microorganisms
- However, not compatible with ILE
In stable formulas, what is often the size of normal fat droplets?
Often >5 um
What is the recommendation of filter use with ILE?
-1.2 um
May remove some microorganisms, such as C. albicans
What is the recommended filter for use with dextrose-AA PN?
-0.22 um
CDC recommendations on ILE hang time when incorporated into dextrose-AA?
12 hours
CDC recommendations on ILE hang time when incorporated into a TNA?
24 hours
Which of the following is the most appropriate VAD strategy for a patient requiring long-term PN therapy?
A) Use a midclavicular catheter as a cost-effective measure
B) Place a percutaneous nontunneled catheter to initiate PN, then replace it with a implanted port
C) Place a single-lumen, tunnelled cuffed catheter
D) Place a triple-lumen, antibiotic coated catheter to ensure adequate access for future needs
C
Which catheter was originally developed for patients with long-term PN needs?
Tunneled catheter
Why would a midclavicular catheter not be appropriate for long-term access?
Does not provide central access, and long-terms means central
When would percutaneous non-tunneled catheters with aditional features, such as coatings, or multiple lumens be indicated?
For acute, shorter term access
Thrombotic occlusions are most commonly treated with what? A) Thrombolytics B) Anticoagulants C) 10% HCl D) Sodium bicarbonate
A
Catheter occlusions are often due to a thrombotic problem, such as an intraluminal thrombus, extraluminal fibrin sleeve or vessel thrombosis.
What are nonthrombogenic factors which may cause a catheter occlusion?
-Intraluminal drug and lipid precipitates
Pharmacological agents that change ___ within the lumen will increase the solubility of the precipitate
the pH
Which of the following practices have been shown to reduce the risk of catheter-related bloodstream infections?
A) Systemic use of antimicrobial prophylaxis at time of insertion/access
B) Routine placement of central venous access devices (CVADs)
C) Use of “central line bundle” of insertion and main tenance practices
D) Selection of an internal jugular site as opposed to subclavian site
C
What does the central line bundle for insertion and maintenance consider? (5)
1) Hand hygiene
2) Maximal barrier precautions
3) Skin antisepsis with chlorhexidine gluconate
4) Optimal catheter site selection
5) Daily review of line necessity, with prompt removal of unnecessary lines
What is the systemic use of antibiotic prophylaxis associated with?
May promote resistance of microbial populations associated with catheter infections
What does blood flow rely on in the large central veins, such as the IVC and SVC?
- Negative thoracic pressure
- Abdominal and diaphragmatic muscle movement
- NOT on valves
Unlike arteries veins can _____
compensate for occlusions via rich collateral circulation
What is the preferred vessel for central access ?
- The SVC
- Estimated blood flow of 2000 ml/min
- Concentrated antibiotics, vesicants and PN can be infuse without causing damage to veins
If the SVC becomes occluded or thrombosed, what may be an alternative site of access?
-the IVC
What measures the outside diameter of a tube?
- French
- 1 mm = 3 fr
What measures the inside diameter of a tube?
mm
What is gauge inversely proportional to?
Outside diameter
What are multi-lumen catheters?
Provides for simultaneous infusion of multiple solutions or incompatible drugs
Why are cuff often attached to CVCs?
- Serve as subcutaneous anchors and mechanical barriers
- If they have silver irons, may exert short-term anti-microbial activity
What are the 3 types of catheters indicated for peripheral access?
- Peripheral (least risk fo catheter related infections)
- Midline
- Midclavicular
In a peripheral catheter, where is the tip located?
located outside the central vessels
In a central catheter, where is the tip located?
In the distal SVC, IVC or right atrium
Infusion of PPN dextrose and osmolality limitations?
- No more than 10% dextrose
- No more than 900 mOsm/L
The leading complication fo peripheral access is peripheral venous thrombophlebitis, what are the hallmark signs and symptoms?
- Pain
- Eryhtema
- Tenderness
- Palpable cord
CDC guidelines recommend close monitoring of the peripheral access, with the line being removed _____
no more than every 72 to 96 hours, unless clinically indicated
When may a midline peripheral catheter be considered?
When treatment is considered for 2-6 weeks
Which catheters are the most common in acute care setting for therapies of short duration?
Non-tunneled, non-cuffed CVADs (central)
The subclavian vein is a common site of venipuncture when administering CPN, what is the risk of repeated use?
- Stenosis
- Serious risk for patients with renal concerns
- The right internal jugular vein is the best approach for patients with CKD who may require dialysis
What are the 3 categories of CVADs?
- Tunneled
- Non-tunneled
- Implanted
What is a PICC?
- A non-tunneled CVAD
- A catheter inserted via a peripheral vein with the tip in the CVC
What is the difference between tunneled and non-tunneled?
Tunneled associated with less infections, due to a seperation between venipuncture and exit site
When may we use translumbar, transhepatic and transcollateral venous access?
- Alternate vein sites if common vein sites are over-used
- These sites may be the only way to provide long-term access for PN and other medications
What are TIVADs?
- Totally Implanted Venous Access Devices (subcutaneous)
- Central access, and cosmetically more desirable
What is the recommended 0.9% NaCl flushes for central access lines?
- Flush before and after each use, or daily if not in use.
- Minimum flushing is equal to twice the internal volume of the VAD system + 20%
What is a CRBSI?
Catheter related bloodstream infection
What is the appropriate treatment for a catheter-related bloodstream infection in a patient with a tunneled cuffed vascular access catheter?
- Gold-standard for CRBSI required catheter removal, but if long-term catheter salvage may be OK
- Collect CV blood cultures, where those that becomes + 2 hours sooner than the peripheral culture are considered predictive for CRBSI’s
What is the tx in the case of a CRSBI?
- Systemic antibiotic therapy
- 70% ethanol catheter lock of 2ml daily with a 6 hr dwell time
Signs and symptoms of CRSBI?
- Elevated WBC (>10,500/mcL)
- Fever, chills, malaise, N/V
- Hypotension, tachycardia, headache, backache
What causes a thrombotic occlusion?
-vessel wall damage
-blood flow changes
-a systemic alteration in circulation
All will arise from the catheter which disrupts blood flow, and can cause venous injury
What are the leading causes of intraluminal occlusions?
- Drug-heparin interactions
- PN formulations with inappropriate calcium-phosphate ratio
- Lipid residue
What is catheter pinch-off syndrome?
Mechanical obstruction of the catheter related to postural changes caused by catheter compression between the clavicle and the first rib
Which of the following is the most metabolic complication associated with PN?
- Hyperglycemia
- Associated with overfeeding
- Can arise from insulin suppression and resistance as well as gluconeogenesis from stress and infection
Non-diabetic hospitalized patients receiving IV dextrose infusion rates higher than ___ have ____ % chance of developing hyperglycemia
- 4 mg/kg/min
- 50%
What is azotemia associated with?
- Renal or hepatic dysfunction
- Protein overfeeding
Why does hyperammonemia rarely occur?
As PN solutions use crystalline amino acids
One day after initiating PN in a critically-ill adult patients, the patient displays low potassium, low phosphorus and normal serum magnesium. The current PN regimen provides:
- 90 g protein
- 150 g dextrose
- no lipid
- minimum volume
- K+ 80 mEq, P 40 mmol
- Standard doses of sodium, magnesium, calcium, vitamins and trace elements. The patient weighs 60 kg and has a BMI of 18. What is the most appropriate response to the lab values?
Provide supplemental IV doses of potassium and phosphate today, but do not change the macronutrient doses with tonight’s PN bag
Provide supplemental IV doses of potassium and phosphate today, but do not change the macronutrient doses with tonight’s PN bag –> Discuss why, what is the management and prevention of refeeding syndrome?
1) Identify patients at risk
2) Serum electrolyte monitoring and aggressive replacement
3) Slowly increasing E intake
- -> if this critcially-ill patient does not have proper K+ and P levels after the initiation of PN, the protocol is to be treated with IV infusion. Energy intake from PN should NOT be advanced until electrolytes are corrected.
Which of the following measures would be considered beneficial in a patient who develops cholestasis while receiving long-term PN that is infused 12 hours nightly?
A) Stop all oral and enteral intake
B) Switch from cyclic to continuous method of PN administration
C) Decrease lipid injectable emulsion (ILE) dose from 1.5 g/kg/day to 1g/kg twice weekly
D) Increase protein dose from 1 g/kg/day to 2 g/kg/day
C
What is cholestasis associated with?
ILE doses greater than 1g/kg/day in adult patients receiving long-term PN
What has cyclic feeding been shown to do?
Reduce serum liver enzymes and conjugated bilirubin concentrations when compared to continuous infusions
(T/F) Protein dosing in PN is associated with developing cholestasis in the adult
F
Which of the following PN modifications is recommended to help prevent and/or treat osteoporosis in the long-term PN patient?
A) Maintain protein intake of at leas 2 g/kg/day
B) Provide more than 20 mEq calcium per day
C) Add injectable vitamin D to the PN formulation
D) Provide 20-40 mmol phosphorus per day
D
An inadequate phosphorous dose may increase urinary calcium excretion
Why don’t we supplement more calcium with PN to prevent osteoporosis?
Limited by calciums compatibility with phosphorus (will form a precipitate) and higher calcium doses are offset by higher urinary losses.
What is the preferable form of calcium supplementation?
Calcium gluconate of 10-15 mEq/day to be added to the PN formulation
What have high protein doses (2g/kg/day) been associate with?
-Increase calcium excretion
Why may excessive vitamin D be detrimental to the bone?
- Suppress PTH and promote bone resorption
- PN formulations of ergocalciferol and cholecalciferol are not available
What is stress-associated hyperglycemia?
- Occurs in acutely ill and septic patients
- Develops as a result of insulin resistance, increased gluconeogenesis, glycogenolysis and suppressed insulin secretion.
What is excessive CHO administration associated with?
- Hyperglycemia
- Hepatic steatosis
- Increased CO2
PN should be administered at ___ the estimated E needs, or approx. ___ g of dextrose for the first 24 hours
50%
150-200
When may the delivery of less dextrose (~100 g) be warranted?
-patient with low BMI or poor glucose control
CHO administration rate should not exceed what?
4 to 5 mg/kg/min or 20-25 kcal/kg/day in acutely ill patients.
The dextrose dose in the PN formulation should not be advanced until ____
the patients blood glucose concentrations are controlled
In rare cases, what may hyperG be related to?
- Chromium deficiency
- insulin is less effective during a chromium deficiency
When may PN associated hypoG occur?
- Excess insulin infusion via PN, IV or subcutaneous injection
- Abrupt discontinuation of PN (rebound hypoglycemia)
When is rebound hypoglycemia more common ?
In patients who require a large amount of insulin
How can we avoid rebound hypoglycemia when discontinuing PN?
-Dextrose containing fluid should be infused for 1-2 hours following PN discontinuation
Why is endogenous production of linoleic (omega-6) FA reduced in PN?
If hypertonic dextrose infused, insulin secretion increases, thus reducing lipolysis.
-Linoleic acid can be endogenously produce through lipolysis of adipose tissue
ILE requirement to prevent EFAD?
250 ml of 20% administered over 8-10 hours, twice a week
____ ILE’s have been associated with immune-suppressed effects through activating the ___
Soy-based
Arachidonic pathway
–> withhold soy based formula within the first week of PN in the critically ill
When can hyperTG occur?
-Dextrose overfeeding or rapid administration rates of ILE (>0.11 g/kg/h)
ILE intake should be restricted to less than _____ of total energy or ____
30%
1 g/kg/day
Propofol is supplied as a ____
10% ILE
What is a possible allergic rxn to ILE?
Egg-phospholipid
What is azotemia?
- Intolerance to protein load, cannot meet the demands od disposing the byproduct of protein metabolism (urea)
- Prone to patients with renal or hepatic dysfunction
What can azotemia arise from?
- Excess protein
- Dehydration
- Inadequate energy prom non-protein sources
Should we restrict protein in patients with liver failure, encephalopathy and hepatic failure?
Not recommended due to LBM loss
What parameters should be monitored, and in what frequency to help identify and prevent metabolic consequences associated with TPN?
- Normalize fluid and electrolyte status, replete if necessary and monitor daily until stable.
- Administer PN slowly, and then titrate to reach goal to prevent hyperG
- Monitor glucose every 6 hours until patient is euglycemic
- Evaluate prealbumin: low levels may indicate inflammatory metabolism
excessive amounts of which vitamins may be toxic?
Fat soluble
(T/F) IV multivitamin therapy should be delayed until there are clinical signs of deficiency
F
-Should receive standard dose of parenteral multivitamins
Monitoring in PN and warfarin therapy?
-Vit K
Monitoring in PN and alcoholism?
Thiamine
What is a key nutrient which may degrade in long-term TPN?
Vitamin A
-Degrades if added to mixture too soon
In long-term TPN, which trace elements may be reduced or removed to avoid toxicity?
Manganese and copper
___ is not included in the PN formulation
Iron
-Provided via PN on a “as needed” basis
Define re-feeing syndrome
The adverse effects of metabolic and physiological shifts of electrolytes, vitamins and minerals that can occur as a result of aggressive nutrition support or nutrition repletion of a malnourished patient
When is re-feeding syndrome at the greatest risk?
2-5 days after the start of nutrition support
Explain the complications of re-feeding
In pro-longed starvation, our body will derive energy from ketones, decrease energy expenditure, reduce insulin signalling. When there is a reintroduction of CHO, we shift to glucose as the main fuel again. Insulin is released, and there is an enhanced uptake of glucose, electrolytes, minerals and water into the cells. There is a increased demand of P to synthesize ATP, as well as increased demands for thiamine, potassium and magnesium to oxidize glucose. Can cause neuromuscular, CVD and respiratory compromises. Fluid and sodium from the nutrient delivery worsens the situation, and can result in fluid overload and edema.
How can the complications of RF syndrome be minimized when providing PN to a nutritionally depleted patient?
- Hemodynamically stable and electrolyte and thiamine replenishment
- Start nutriton slow at 50% of needs or 15 kcal/kg/day
- Protein should remain the same, as it has less of an impact on glycolysis
- The remaining kcals should comprise of dextrose and fat
- Dextrose should never exceed 200 g/day
- Increase to full goal rate over 2-5 days
- Monitor electrolytes and weight daily
- Administer vitamins and trace elements daily
(T/F) re-feeding hyperphosphotamia has the same metabolic complications as refeeding syndrome
F
-however, concerning and replace with phosphate supplement
What are the three kinds of heptobiliay disorders associate with PN?
- Steatosis (Fat infiltration, due to overfeeding)
- Cholestasis (impaired secretion of bile)
- Gallbladder sludges/stones (Likely due to lack of EN stimulation)
Macronutrient compostions of PN which may favour steatosis?
1) Excessive energy
2) Low-fat (more CHO)
3) Protein hydrosolates (we now use crystalline AA)
What is high-soybean oil ILE associated with?
- High omega-6 and phytosterols
- Inflammatory and immuno-suppression
- May contribute to biliary sludges and stones and other hepatoxic effects
Liver complications are associated when both lipids are ____
high and low
- -> Low due to EFAD
- -> high to due inability to clear fatty acids in liver
how is choline usually produced?
From methionine, which is included in the PN but is less effective
Implications of low choline?
Elevated hepatic aminotransferase and steatosis
Strategies to manage PN associated lover complications?
- Decrease dextrose
- Decrease ILE to <1 g/kg/day
- Provide balance of dextrose and ILE
- Cyclic PN infusion
Why should oral and enteral nutrition be optimized whenever feasible for patients on long-term PN?
To promote the enterohepatic circulation of bile acids
Consequence of continous PN feeds?
Can result in hyperinsulinemia and fat deposition in the liver, therefore potentially increasing the risk of liver diseases
–> May be indicated for cyclic PN
What is the metabolic bone disease caused by vit D deficency?
- Osteomalacia
- Bones contain oteoid tissue which fails to calcify
____ have reported osteoporosis after at least 6-months of at home TPN
41-67%
Paradox of vitamin D in bone health?
Both vitamin D deficiency and toxicity can result in bone disease
Strategies to prevent and treat osteoporosis in patients receiving long-term PN?
- Avoid high doses of protein
- Avoid excessive doses of sodium
- Calcium supplement of 10-15 mEq/d
- Phosphorus: 20-40 mmol/d
- Treat metabolic acidosis
- Maintain adequate Mg, Cu, Al
- Avoid heparin
