- Nutritional support given IV when enteral not safe/effective (macro+micronutrients) - Not disease-specific, but provision of calories/energy used to prevent malnutrition

Parenteral Nutrition Flashcards by Allison Chan

What is TPN?

Nutritional support given IV when enteral not safe/effective (macro+micronutrients)
Not disease-specific, but provision of calories/energy used to prevent malnutrition

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TPN General Problems

Expensive with risk of serious ADEs (appropriate use is essential)
- Must recognize when and when not to use
- Tailor to patient
- Monitor and adjust as needed
- Transition to enteral ASAP

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TPN Adult Indications

Healthy adult unable to receive significant EN: Initiate after 7 days

Nutritionally-at-risk patients unlikely to achieve goal: Initiate within 3-5 days

Baseline moderate-severe malnutrition (EN not feasible): Initiate ASAP

Delay in metabolically unstable patients until condition improves

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“Nutritionally-at-risk” criteria

One or more:
- Involuntary weight loss: 10% <6mo, 10lbs <6mo, 5% <1mo
- BMI < 18.5 kg/m^2
- Increased metabolic requirements
- Altered diet and/or diet schedule

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TPN Pediatric Indications

Limited data (can delay up to 7 days in a self-resolving illness situation)

If unlikely to tolerate EN for extended time:
Infants (1mo-1y): Initiate within 1-3 days
Children/adolescents: Initiate within 4-5 days

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Why do we initiate TPN sooner in pediatrics?

They have
- Decreased metabolic stores/reserves available
- Higher energy requirements

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TPN Neonate Indications (0-1mo)

Very-low birth weight (<1.5kg): Initiate promptly after birth

Preterm and critically ill term neonates: Initiate when EN unable to meet energy requirements for growth

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Concern when holding fat in neonate diet for 3 days?

Essential fatty acid deficiency
(impacts brain development)

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TPN Indications Any Age

Impaired absorption (short bowel, high output intestinal fistula, gastroschisis)
Mechanical/motility issues (obstruction, ileus, inflammatory disease)
“Bowel rest” required (pancreatitis, ischemic bowel, pre/post-operative)
Inability to utilize EN (VLBW infant, hemodynamic instability, severe GI bleeding)

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TPN Types of Complications

Metabolic

Mechanical

Infectious

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TPN Metabolic Complications

Hypo/hyperglycemia (target 140-180 mg/dL)
Electrolyte imbalances, refeeding syndrome (hypoK, hypophos, hypoMg)
Hypertriglyceridemia
Liver function abnormalities acute (AST/ALT elevations) and chronic (Alkaline Phos/Bilirubin > weeks)

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TPN Mechanical Complications

Pneumothorax
Catheter occlusion
Thrombus
Phlebitis (extravasation of TPN)

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TPN Administration: Peripheral line

Bedside insertion into veins of forearm/hand
Use for short-term duration

BUT

Increased phlebitis risk
Upper osmolarity limit of 900 mOsm/L
Not suitable for home TPN or long term

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TPN Infectious Complications

Central line associated infections, bacteremia

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TPN Administration: Central line (PICC)

Bedside insertion into basilic, cephalic, or brachial veins (tip in superior vena cava)
Suitable for short to medium duration of TPN

BUT

May require radiologist
Increased DVT risk
Site: limits pt activity, easily removed, easily infected

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TPN Administration: Tunneled catheter (Broviac, Hickman)

Suitable for long term TPN, cuffed to minimize contamination/dislodgement
Minimal restrictions to activity
Easier for self-care/hidden

BUT

Surgical/radiology guided insertion

TPN Monitoring

Electrolytes
Glucose
Liver functions

Long term: conjugated bilirubin, triglycerides

Individualized, others may require different levels of trace elements, nitrogen balance, etc…

What is refeeding syndrome?

Occurrence of electrolyte abnormalities (rapid depletion) in severely malnourished patients during rapid initiation of nutrition
- Can lead to fluid overload (monitor fluid status carefully)
- Start slow and advance over 3 days, initiate TPN at 1/2 of goal rate

Which electrolytes do we pay attention to specifically in refeeding syndrome?

Monitor and aggressively supplement: Potassium, phosphate, magnesium

TPN approaches

Standard approach: Commercial premade TPN bags, NOT for pediatrics

Individualized approach: Compounded prescription TPN, used in NICU/pediatric patients

Cycled TPN: Provided over a rate that is not the usual 24h, used in long term to allow “off time” and minimize risk of IFALD, ramp up and down rate, avoid drastic glucose shifts.

Calculating fluid goals

Neonates: Initial 60-80mL/kg/day, titrated to 120-150mL/kg/day

Pediatrics: 4-2-1 method
1. 0-10kg: 4mL/kg/hr
2. 10-20kg: 2mL/kg/hr
3. any kg>20: 1mL/kg/hr

Adults*: 30-40mL/kg/day
Critically ill adults: minimal mL/kg/day to achieve adequate nutrition

Amino acids (protein)

4kcal/gram
10mOsm per g/L or 100mOsm/%
Various solutions available

Nitrogen balance

We want positive (anabolic state, energy in > energy out)

Nitrogen IN: Grams of protein / 6.25 = grams of nitrogen
Nitrogen OUT: UUN (g) + 4
Formula = IN - OUT

UUN = urine urea nitrogen, collected over 12-24 hours
+4 for insensible losses

Increase protein if nitrogen balance is negative

Dextrose (carbohydrates)

3.4kcal/gram
5mOsm per g/L or 50mOsm/%
Peripheral limit D10-12.5%
Product = D70W

Lipid emulsions (fat)

- 9kcal/gram - Various products with different fat concentration - Maximum rate of infusion** = 0.15g/kg/hr in pediatrics, 0.11g/kg/hr in adults - Must administer with a 1.2 micron filter (3-in-1s) - Maximum hang time of 12 hours - Certain emulsions may be contraindicated in egg/soybean/fish allergies

Monitoring pearls for lipids

IFALD: liver function tests and bilirubin Hypertriglyceridemia: TG > 200 mg/dL (neo./ped.), TG > 400 mg/dL (adults) EFAD: essential fatty acid profiles in malnourished neo./ped. patients or any patient using lipid minimization strategies.

Calcium-Phosphate Precipitation

Concentration dependent reaction leading to in-solution precipitates to form Affected by: - Dose of Ca/Phos - pH - Temperature - Time - Salt form (calcium gluconate preferred) Separate addition to minimize risk - PHOS FIRST***

Multivitamins

- MUST be included for standard dosing TPN - Essential for various organ systems and physiological function - Some patients may need more (individualize) - long term TPN - Monitor patients on warfarin - contains vitamin K

Trace elements

- Zinc - Copper - Manganese - Chromium - Selenium

Anion balance

Positive cations MUST be with negative anion - Ordered based on mEq of cations in TPN - Acetate or chloride, 1:1, 2:1, 1:2, maximum one or the other Metabolic ACIDOSIS = increase acetate, decrease chloride Metabolic ALKALOSIS = decrease acetate, increase chloride

Lipid compatibility problems in TPN (3-in-1)

Creaming: safe to use, reversible Cracking: UNSAFE to use, irreversible separation Minimum concentrations for stability: AA 4%, Dextrose 10%, ILE 2%

Medications in TPN

(insulin, levocarnitine, heparin, famotidine) - Check compatibility - Determine risk or clinical utility provided over 24h

Filter requirements

Dextrose-AA: 0.22 micron filter Lipids/3-in-1: 1.2 micron filter

TPN Use in Special Populations

Hepatic failure/disease: higher branch amino acid, lower aromatic Diabetes: lower carbs, higher fat COPD/lung disease: lower carbs, higher fat (less CO2) Trauma/burns: increased metabolic needs, higher calories, more protein

TPN order steps for adult

1. Evaluate fluid and energy requirements 2. Calculate kcal/day, g/day, and mL for each macronutrient 3. Determine final concentrations of dextrose, AA, and lipids 4. Calculate electrolyte doses (consider special circumstances) 5. Select appropriate anion balance 6. Perform "safety checks" - Max lipid rate 0.11 g/kg/hr - Glucose infusion rate close (less than) 4 mg/kg/min - Estimate osmolarity (AA + dextrose) - Check line/access (central vs. peripheral) - if TNA (3-in-1), ensure appropriate macronutrient % for lipid stability

TPN order steps for pediatrics (2-in-1)

1. Evaluate fluid and energy requirements 2. Calculate kcal/day, g/day, and mL for each macronutrient 3. Determine final concentrations of dextrose, AA 4. Calculate infusion rates (mL/hr) for 2-in-1 and lipid infusion 4. Calculate electrolyte doses (consider special circumstances) 5. Select appropriate anion balance 6. Perform "safety checks" - Max lipid rate 0.15 g/kg/hr - Glucose infusion rate (mg/kg/min) - Estimate osmolarity (AA + dextrose) - Check line/access (central vs. peripheral)