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NUTR 476 Advanced Clinical > Parental Nutrition > Flashcards

Parental Nutrition Flashcards

1
Q

Indications for PN use

A
  • Significant bowel dysfunction resulting in inability to achieve adequate enteral nutrition for > 7-10 days for adults (4-5 days for children & adolescents (2-18 years), or 1-3 days for infants/toddlers)
  • Hypermetabolism with inability to meet needs via GI tract.
  • Moderate-to-severe pancreatitis (or other GI diseases when patients present with acute adverse GI symptomology) requiring bowel rest > 7 days
  • Bowel dysfunction
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2
Q

Contraindications to PN

A
  • When the gut works, PN is contraindicated!!
  • Previously well nourished adults where GI tract is expected to be functional in 7-10 days
  • Prognosis does not warrant aggressive nutrition support (eg. palliation; note: PN can be part of palliation in children, not typically in adults)
  • Vascular access is severely compromised and complications/risk associated with PN is greater than potential advantages.
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3
Q

Clinical conditions warranting cautious use of PN

A
  • Severe hyperglycemia
  • Severe end-stage renal failure
  • Multi-organ system failure
  • Severe metabolic acidosis or alkalosis
  • Severe electrolyte disturbances (typically associated with severe metabolic acidosis/alkalosis).
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4
Q

Complications of PN

A
  • Typically due to overfeeding and lack of GI stimulation
  • Cholestatic liver disease (includes abnormal hepatic and biliary function) ± liver steatosis
  • PN associated cholelithiasis (due to decreased secretion of cholecystokinin (CCK))
  • Infection
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5
Q

What is Cholestasis?

A

reduction or stoppage of bile flow

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6
Q

Risk factors for cholestatic liver disease

A
  • Prematurity of birth
  • Duration of PN
  • Infection
  • Lack of enteral stimulation
  • Bacterial overgrowth
  • Overfeeding
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7
Q

What is cholelithiasis?

A

gallstones → hardened deposits of digestive fluid that can form in your gallbladder.
* The gallbladder is a small organ located just beneath the liver. The gallbladder holds a digestive fluid known as bile that is released into your small intestine.

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8
Q

Describe PIV

A

PIV = peripheral intravenous line (Peripheral Lines)
* usually last for 5-7 days; meant for short-term IV access
* Can only handle hypotonic or iso-osmolar solutions
* Mid-line: peripheral IV access last up to two weeks (not to be confused with a med-line (IV that delivers meds) which may be a CVL or PIV)
* Usually inserted in arm, feet or head (infants); can be elsewhere

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9
Q

mid-line versus med-line

A
  • Mid-line: peripheral IV access lasting up to two weeks
  • med-line: IV that delivers meds which may be a CVL or PIV
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10
Q

Describe CVL

A

CVL = central venous line (central lines)
* May last for months or years
* Can handle hypertonic solutions
* Multiple types
* Typically inserted into chest, arm or leg (eg femoral vein) typically bigger, central vein

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11
Q

Where do most chest catheters get inserted?

A

in the subclavian vein

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12
Q

Examples of CVL

A
  • port-a-catheters
  • chest catheters (eg. Hickman, Broviacs)
  • PICC line
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13
Q

Describe the Broviacs & Hickman CVL

A

Types of central lines which differ in lumen diameter (Broviac is smaller lumen size)
* Catheter is placed directly into a central vein, usually in neck, upper chest, or groin and proceeds to position just above the heart (away from site where it enters the vein)
* May prevent bacteria from gaining access to central portion of catheter
* Are tunneled venous catheters
* Used for long term or recurring therapies

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14
Q

Describe portacatheters

A
  • Access device: Central Line
  • Located under the skin in the chest wall
  • Often used when only need intermittent intravenous access (eg. patients on chemotherapy)
  • Do not typically use for administration of PN
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15
Q

Device related complications

A

Infectious (most frequent); need to use aseptic techniques when handling IV lines
* Endogenous skin flora
* Contamination of catheter site
* Contamination of infusate (PN)

Non-infectious (Mechanical)
* Catheter occlusions
* Thrombosis
* Breakage
* Phlebitis (inflammation of vein near skin)

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16
Q

Peripheral vs Central PN

A

Peripheral PN
* PN is needed less than 2 weeks
* Patient not fluid restricted
* central PN not feasible
* Can meet BMR

Central PN
* PN is needed for more than 2 weeks
* Patient is fluid restricted
* Peripheral access is limited
* Total nutrient needs can be met

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17
Q

How do dextrose solutions for PN typically come?

A

In a PN pharmacy dextrose stock solutions are usuall yprovided as a D70W or 70% dextrose (this is a concentrated form of dextrose).

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18
Q

How are the dextrose stock solutions delivered to patients?

A

PN pharmacists dilute down the dextrose stock solutions to deliver lower concentrations to the patient.
* usually given to patient as a 10% or 20% (but can be a special, for example 17.5%)

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19
Q

How many calories does dextrose in PN provide?

A

Supplies the majority of non-protein calories and osmolality
* Provides 3.4 kcal/g

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20
Q

How is dextrose reported?

A

Typically reported in g/L concentrations on PN bag
* 10% solution = 100 g/L
* 20% solution = 200 g/L
* 30% solution = 300 g/L

30% not commonly used in AHS; but can be used substantially elsewhere.

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21
Q

How much dextrose can go into CVL vs. PIV?

A

% dextrose determined by type of IV line –solutions with > 12.5% dextrose cannot be infused via a PIV due to risk of phlebitis and decreased life span of line
* CVL=10-30%
* PIV = anything less than 12.5% w/v

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22
Q

What are the steps for dextrose concentration and kcal received?

A
  1. Multiply % dextrose given (D%W) by 10 to get the concentration in g/L
  2. Multiply the dextrose grams by the total amount of litres to determine the total amount of dextrose in the infuse (in grams)
  3. Multiply the total dextrose (g) by 3.4 kcal/g to get kcal amount for dextrose
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23
Q
  • What is the concentration of D7.5W?
  • If you wish to make 1.5 litres of a D7.5W how many kcal would you get??
A
  1. 7.5% x 10 = 75 gm in 1 L.
  2. 75 g dextrose x 1.5 L = 112.5 g dextrose
  3. In 112.5 g dextrose x 3.4 kcal/g = 382.5 kcal from dextrose.
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24
Q

What is the concentration of D5W and how many Kcal does it provide in 1500 mls.

A
  1. D5W provides 50 g dextrose in 1 litre or 50 g/L.
  2. In 1500 mls this provides 50 g dextrose X 1.5 L Litres or 75 g of dextrose.
  3. 75 gm of dextrose x 3.4 kcal/g = 255 kcal from dextrose
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25
Q

What might excess CHO in the PN lead to?

A
  • Lipogenesis (conversion to fat) leading to liver damage
  • Increased CO2 production (respiratory distress)
  • Hyperglycemia (stress/insulin resistance, steroids, sepsis)
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26
Q

What does CHO contribute to which may be a problem?

A

Contributes to osmolality – watch in pts with PIV’s
* If in excess of the pancreas’ ability to secrete insulin get hyperglycemia; exceed renal threshold and get spilling of glucose into urine

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27
Q

What needs to be considered to prevent hyperglycemia due to high osmolality?

A

GIR - glucose infusion rate

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28
Q

Why is hyperglycemia a problem?

A
  • insulin resistance
  • iatrogenic diabetes
  • renal and liver damage
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29
Q

How much glucose is okay in PN?

A

Adults: 3-5 mg/kg/min
* Typically should aim for < 4 mg/kg/min if possible (usually not more than 20-25 kcal/kg of CHO max). May give less if no problems with liver.
* When cycling of PN for Home PN; dextrose infusion rates may be higher; risk for metabolic syndrome/liver issues increases.

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30
Q

GIR calculation

A
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31
Q

What is the GIR for 18 yr old, weighing 49 kg, receiving 1753 ml of 200g/L dextrose solution PN running over 21 hrs? Are they on CVL or PIV?

A

5.7 mg/kg/ min and CVL since 200 g/L would be 20%
* This is too much!

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32
Q

What are the ways to impact the GIR?

A
  • Change the dextrose concentration
  • number of hours the dextrose is run over
  • the volume of the dextrose that is delivered
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33
Q

What is the GIR for a 35 year old man, weighing 65 kg, receiving 1950 mls of a 17.5% w/v dextrose solution over 24 hours?

A

3.65 mg/kg/min

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34
Q

What lab variable are important to monitor for tolerance to IV GIR?

A
  • Random blood sugars: should be 4.0-6.0 mmol/L
  • Blood sugars over 10 mmol/L; exceed renal threshold; get spilling in urine (GLYCOSURIA) \ glucose in urine should typically be zero (if positive then the dextrose infusion rate is too high!)
  • May have elevations in liver biochemical functions (aspartate amino transferase ( AST) and alanine aminotransferase (ALT)) due to steatosis! (only when in great excess)
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35
Q

When might hyperglycemia occur with PN?

A
  • Occurs when GIR administration in excess of recommended ranges (>5 mg/kg/min in adults)
  • Patients on corticosteroids (eg. prednisone) for treatment of chronic disease (e.g IBD).
  • Patients with high counter-regulatory hormone because of trauma, surgery
  • Infection
36
Q

What are potential treatments to hyperglycemia due to PN?

A
  • First line: Decrease IV glucose administration rate or total dose
    Potentially insulin: but should not be used if issue due to IV administration issues!
36
Q

When is too little dextrose given?

A
  • GIR very low (< 2 mg/kg/min); suboptimal kcal via PN likely
37
Q

What is the normal liver response to too little dextrose? What happens with chronic disease?

A
  • In normal liver glycogenolysis and gluconeogenesis produce blood sugar to keep in normal range, but get muscle wasting and ↑ production of ketone bodies from body stores of fat
  • If liver is malfunctioning due to chronic disease you get low blood sugar (can also occur if abruptly stop PN)
38
Q

What populations are at risk of receiving too little dextrose?

A

premature infant & patients with liver disease
* Monitor blood sugars!
* Increase GIR; cycle down PN slowly…

39
Q

When might low dextrose be used?

A

For other IV solutions (D5W) rates less than 2 mg/kg/min are not uncommon; for individuals with healthy livers (for most adult clinical (non-ICU) populations this may not be an issue)

40
Q

What is cycling PN?

A

Refers to the process of decreasing PN administration rate (mls/hr) prior to stopping PN administration and/or when preparing a patient to be D/Ced on Home PN so they may be on less than 24 hrs of PN administration
* Particularly important for patients where dextrose concentration in PN is >125 g/l or GIR >4 mg/kg/min (reflects rate of endogenous glycogenolysis in the body); usually needed for patients receiving PN via CVL

41
Q

When would you cycle PN?

A
  • When D/C PN all together
  • When need to hold PN due to administration of other IV meds (these may not be compatible with PN solution and therefore the PN must be stopped)
  • To facilitate some free time off of PN (eg. physical therapy, for tests and procedures, to promote quality of life as in a patient on Home PN)
42
Q

Why is cycling PN important?

A

At higher dextrose concentrations circulating levels of insulin tend to be higher; if you stop PN abruptly then body does not have a chance to respond to change in glucose delivery and you get an abrupt drop in blood glucose concentrations due to the higher circulating levels of insulin.

43
Q

How to cycle PN amino acid/dextrose solution

A

cut rate approximately in half in last hour of infusion.
1. Subtract off 30 minutes from the goal cycle time
2. Take total volume of solution ad divide it by step 1 value to get the feeding rate for the cycle except for the last hour
3. Subtract volume in 1 hour less from goal volume (from step 2) from the total volume of solution to get feeding rate for the last hour
4. Round value down for feeding rate

44
Q

Cycling PN: Case 3

34 year old male on PN solution, weighing 75 kg, containing 27.5% dextrose (275 g/L) at a rate of 80 mls/hr x 24 hrs (1920 mls). Goal is to cycle PN off for 4 hours to ensure that he is able to go outside the hospital for a special family celebration.

A

See Lecture 2 Slides 28-32

45
Q

What are contraindications to cycling PN?

A
  • peripheral line (this route of IV access can limit ability to cycle PN as these types of smaller veins may not tolerate higher rates).
  • GIR too high
  • premature infants & liver pts (hepatic glycogen stores may be insufficient + ?minimal po intake → at risk for hypoglycemia)
46
Q

Parental amino acids contribution

A
  • Maintains or promote spositive nitrogen balance; prevents catabolism of body protein to meet metabolic needs
  • Contributes to the acidity of the solution; protein intake may be limited in pts with PIV’s
47
Q

How are PN AA delivered?

A

Delivered as a synthetic crystalline amino acid solution.
* Typically the stock solution is 10% w/v (that is the solution the pharmacist must use to prepare more diluted preparations for the patient).
* primene (standard) and travasol C ( plus others)

48
Q

What can be a problem of AA adding acidity to the solution?

A

By-products of amino acid metabolism may produce metabolic acidosis
* Metabolic acidosis can be modified by the addition of the buffer Acetate
* Partial replacement of chloride by acetate in the amino acid (aa) solution can result in improved pH

49
Q

kcal contribution of AA to PN solution

A

4 kcal/g

50
Q

AA concentration in PN solution

A

Range from 10 g/L usually to maximum of 50 g/L; but may vary (50 g/L = 5%)
* Most adult formulations are 30 g/L
* for fluid restricted patients 50 g/L.
* * Typically between 25-50 g/L; 2-3% is PIV and >4% move to CVL

51
Q

Adult requirements for parental protein

A

1-1.5 g/kg; usually start at 1.0 g/kg and then move up following days to max determined
* may be higher in sepsis or if patient was malnourished
* Need to consider renal function: monitoring serum levels of urea/creatinine

52
Q

Guidelines for administration of PN AA

A

caveats
* initial dose may start at 1.5 g/kg/d in ICU
* maximum may go up to 2.0 g/kg/d

53
Q

Interpretation of serum urea

A

recent protein intake, renal function (Normal 3-8.9 mmol/L). Elevated urea may be due to:
* excess protein intake via PN
* inadequate energy intake resulting in endogenous protein breakdown
* dehydration
* renal failure (with elevated creatinine)

54
Q

Interpretation of serum creatinine

A

skeletal muscle mass (normal <106 umol/L)
* Impacted by renal disease

55
Q

Interpretation of Albumin

A

visceral protein status (normal 33-58 g/L)
* typically <35g/L is considered low.
* Impacted by the presence of liver (biosynthesis) & renal disease (excretion)
* reflects what happened a few weeks ago

56
Q

Problem of increased ammoniagenesis

A

kidneys and liver damaged so cannot make enough urea and excess ammonia production occurs with the protein intake which can cause neurological damage, encephalopathy, brain damage, death

57
Q

Consequences of too much protein in PN delivery

A
  • Renal damage
  • Weight gain or conversion to fat (esp if PN in excess of energy needs)
  • Increased ammoniagenesis
58
Q

Consequences of too little protein in PN delivery

A
  • Protein breakdown with skeletal muscle mass leading to cachexia
  • Impaired immunity & wound healing
  • Organ dysfunction
59
Q

If a patient weights 85 kg and needs 85 g of protein (1 g/kg/d). How many mls of a 10% Amino Acid Stock solution would this patient need.

A

85 g protein / 0.1 g/mL = 850 ml of the stock solution.
* 85 g protein x 4 kcal/g = 340 kcal

60
Q

How are IV dextrose, AA and lipids typically delivered?

A
  • dextrose and AA are delivered together in a mixture
  • lipids are delivered separately from dextrose/AA
61
Q

IV lipid emulsions

A

Different lipid emulsions are available → premis that the type of fatty acids may alter immune & inflammatory response
* Soybean or safflower oil based (eg: Intralipid); comes in 10,20 and 30% forms.
* Fish oil based; eg: Omegaven 10% solution
* Combination MCT/LCT; eg: SMOF or Clinoleic which are both 20% solutions (0.2 g/mL)

62
Q

Benefits of emulsions with increased MCT

A
  • Do not accumulate in the liver
  • Less susceptible to peroxidation
  • Does not participate in eicosanid synthesis
  • Less impact on inflammatory response
63
Q

Problems of high omega 6 LCT?

A

Can be pro-inflammatory

64
Q

Use of 10%, 20%, 30% lipids

A
  • 20% most commonly used in adults
  • 30% for fluid restriced patients
65
Q

What is an important consideration when choosing type of dextrose, AA and lipid?

A

allergies
* soy, egg, olive, peanut etc

66
Q

What is an important enzyme to consider with lipid delivery?

A

The lipids are dependent on lipoprotein lipase activity for clearance (cleared from the bloodstream in a similar manner to chylomicrons)

67
Q

How is lipid delivery best tolerated?

A

when given over a 24 hr infusion period but can give over shorter infusion rates cautiously
* Edmonton zone over 12 hours
* don’t exceed 0.1 g/kg/hr

68
Q

How many grams of lipid in 250 mls of 20% lipid.

A

250mls x 0.2 g/ml = 50g lipid

69
Q

Guidelines for IV administration in Adults

A

Recommend a maximum of 1 g/kg/d in adults, but may go higher in adolescents or young adults (carefully) up to a max of 2.0 g/kg/d (select populations).
* Start at 0.5 g/kg IV lipids if serum TG are on upper end of normal; increase by 0.5 g/kg to a maximum of 1 g/kg in adults (occasionally may give more such as in adolescents; never exceed 60% of kcal as fat).
* Can keep at same rate throughout infusion therefore just take total volume of lipid and divide by number of hours you want to give PN (should not exceed 0.1 g/kg/hr)

70
Q

provision of kcal from PN lipids

A

10 kcal/ gram
* Should not provide more than 60% of IV kcal as fat.
* Need at least 10% of total kcal to be from fat to avoid essential fatty acid deficiency (more of an issue in neonate or in patients on long term TPN without any enteral nutrition support)

71
Q

What is the rate limit for IV lipid administration?

A

0.1 g/kg/hr

72
Q

What to monitor for lipid tolerance

A

Monitor fasting serum levels of triglycerides and or intralipid (measure of lipid clearance) to determine lipid toleranc

73
Q

Complications from Excess PN Lipid Administration

A
  • Platelet dysfunction
  • Coagulopathy
  • Increased risk for infection
  • Severe Liver Steatosis and organ failure
74
Q

Treatment for excess lipid administration

A

stop IV lipid infusion for 24 hours, monitor blood lipid levels and restart at 25-50% of the rate

75
Q

Energy requirements for PN

A

Influenced by age, disease type & severity, gender, body composition
* Maintenance requirements (adults & children)
* Growth requirements (children)
* BMR x AF x SF or on kcal/kg basis
* Typical adult PN energy needs 25-35 kcal/kg; children and adolescents need significantly more energy on a per kg body weight basis.

76
Q

Application of Stress/Activity Factors

A

Hypermetabolism: can increase energy needs by 30-50%; with PN you need to be cautious of overfeeding
* Need to consider ventilatory status and use of medications: hypometabolism
* Only true way to be certain is to use methods such as indirect calorimetry to measure BMR

77
Q

Overfeeding of PN complications

A

Significant risk = organ dysfunction
* Liver (monitor serum levels of AST, ALT, conjugated bilirubin)
* Renal (urea, creatinine, electrolyte disturbances)
* Pulmonary (increased ventilation, respiratory rates)
* Cardiac (cardiac output influenced); heart rate
* Pancreatic (increased insulin secretion); monitor serum levels of amylase, TG, glucose, insulin

Increased risk for infection

78
Q

What is TFI?

A

total fluid intake (set by MD)
* MD may set TFI in excess of basal fluid requirements or less than basal fluid requirement
* RD’s assist in setting of TFI usually in non- intensive care wards, but MD has final responsibility with this

79
Q

Fluid restrictions and PN

A

Fluid restrictions: may need in patients with end- stage liver or renal disease; may need CVL
* Need to consider TFI of patient
* Are basal fluid needs to be met with PN or is patient on IV meds?
* Use 30% intralipid in fluid restricted or hyper- metabolic patients; may also use 20% intralipid; depends on how tight fluid restriction is and how hypermetabolic the patient is.

80
Q

What weight to assess whe determining fluid requirements

A

Always use the actual weight of a patient when assessing fluid requirements (there are exceptions for intensive care or when patient is fluid overloaded). When patient is fluid overloaded, then the ‘best estimate’ of the patients ‘dry weight’ is used.

81
Q

Standard parental intake for electrolytes

A

Know the electrolytes and the normal value amounts
* Can give more if needed but usually this day 1 and monitored
* If someone is a little on the low side then choose the upper level

82
Q

Reccomended vitamin requirements in PN

A

Do not need to memorize maybe just know the vitamins that are listed here

83
Q

Steps for writing a PN order

A
  1. Physiological Assessment: physiological/ nutritional status, TFI/ fluid restrictions, potential issues with delivery/ what type of delivery
  2. PN Calculations: protein, energy, fluid (standard measures)
  3. Assessing kcal from dextrose and lipids (together): Subtract protein kcal from total kcal they need
  4. Determine IV lipid concentration to give: 0.5-1 g/kg/d and the kcal it would provide
  5. Impact of dextrose kcal with what is left once IV lipids determined
  6. Determine total fluid amount allowed for PN then choose type of lipid: 20% (2 kcal/mL) or 30% (3 kcal/mL) → total lipid kcal/ 2 or 3 kcal/mL = Lipid mL (at 20% or 30%)
  7. Determine dextrose concentration: PIV must be ≤12.49 so many have to adjust lipids to make this or reduce dextrose given; Determine GIR
  8. Calculate the AA concentration in the PN solution as %
  9. Writing out the components in a PN order
84
Q

What are the components of a PN order?

A
  • A: total volume of solutions
  • B: Concentrations of macronutrients (protein, fat, CHO), total gm amounts and g/kg amounts
  • C: Rates of amino acid dextrose solutions and rates of lipid solutions
  • D: kcal from macronutrients (absolute and kcal/kg)
  • E: GIR (mg/kg/min)
85
Q

Practice PN calculation case

A

Week 2

NUTR 476 Advanced Clinical (23 decks)

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