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## TPN: Total Parenteral Nutrition

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**1. **TPN: Total Parenteral Nutrition Chad Bradford. Touro University College of Pharmacy

**2. **What is TPN? A compounded formulation which includes the necessary macronutrients and micronutrients required to sustain life
The formulation is used for patients who are malnourished or at high risk of becoming malnourished because alternative routes of feeding have failed or have become unavailable Chad Bradford. Touro University College of Pharmacy

**3. **TPN Indications NPO = Nothing by Mouth, where patients essentially can not tolerate feedings through the GI tract for a prolonged period
Anatomical Abnormalities
Infants with immature bowels, patients with surgical resections
Motility Problems
Obstructive complications of the GI tract
Critically Ill
Patients with conditions favoring catabolism, Cancer
A typical period is > 5-7 days that is expected to persist > 7-10 days.
TPN is NOT INDICATED for 1 day
TPN is NOT INDICATED for perioperative use
Complications of the line placement and of the formulation itself Chad Bradford. Touro University College of Pharmacy

**4. **Requirements Step 1: Make sure TPN is indicated
Step 2: Obtain baseline labs: Chem 10, LFT, ABG, etc
Step 3: Make sure a central line is in place
TPN is a hyperosmolar formulation 2000-2500 mosmol/L
If TPN is infused peripherally blood cells will undergo implosive lysis and destroy the vein
Central vein infusion dilutes the slow infusion and preserves blood cells and veins
The standard central line placement is in the SVC Superior Vena Cava
Subclavian approach
Jugular approach
PICC Peripherally Inserted Central Catheter
Implant to SVC or SV, with or without a port
Femoral lines are not appropriate
Step 4: If infused at home ensure patient has access to the appropriate pump and supplies as well as caregiving if needed
Step 5: Follow up regarding the patients nutritional status and review labs for adjustments to the formulation Chad Bradford. Touro University College of Pharmacy

**5. **Complications Complication rates increase with duration the catheter is in place and the number of catheter lumens
Catheter related complications are the most common
Long Term
Infection: CRBSI and exit site
Thrombotic
Placement and Catheter
Hemothorax, Pneumothorax
Air embolisms and infections
Metabolic
Acute: E-lyte, Acid-Base, glycemic abnormalities
Chronic: Bone mineral disease, liver disease Chad Bradford. Touro University College of Pharmacy

**6. **TPN Formula Dependent on the individual patients needs and based off of a reference weight.
Use Cockcroft-Gault rules to determine the weight to use: AW, ADJ, IBW
Monitor weight to make adjustments to the formulation
Take into account non-metabolically active weight: fluid from edema, ascites
Total Calories: RDA = 28-29 kcal/kg
The typical range is 20-35 kcal/kg
Not all patients require the same caloric intake therfore you must take into account
Weight: Comparison to ideal weight
Body Content: Fat vs. Muscle vs. Water
Functionality: Normal function vs. Abnormal
Obese Patients: BMI > 30
May require less calories
Inactive Patients
May require less calories
Malnourished Patients: < 80% UBW, < 75% IBW, >10% Involuntary Loss
May require more calories
Critically Ill Patients: Cancer patient in catabolic protein state
May require more calories
Chad Bradford. Touro University College of Pharmacy

**7. **Formula: Macronutrients Chad Bradford. Touro University College of Pharmacy

**8. **Formula: Micronutrients Na: 60-130mEq/d
Available as: NaCl, Na Acetate, Na Phosphate
K: 70-150mEq/d
Available as: KCl, K Actate, K Phosphate
Mg: 8-24mEq/d
Usually Mg Sulfate
Ca: 5-22mEq/d
Usually Ca Gluconate
Phosphate: 15-40mmol/d
Available as Na and K Phosphate
Cl, Acetate
Available as Na and K. Used to balance Acid Base
Multivitamin
Most people receive
Trace: Zn, Se, Cu, Cr, Mn
Most people receive
Electrolytes are adjusted based on patients labs and patients normal reference range.
Ca and Phosphate should be added at two separate times to avoid precipitation and instability of the lipid formulations
Chad Bradford. Touro University College of Pharmacy

**9. **Formula: Misc/Other Drugs may also be added to the formulation
H2RA, Insulin, Fe Dextran etc.
Total Fluid requirements vary by patient age and condition
Stability varies among formulations and facilities
Hospitals make TPN daily: May be stable for less time
Home Infusion makes a weekly batch: Longer stability
Most TPN lasts about 1 month
Most TPN facilities mark them as stable for 7-14 days
TPN is usually started with nutrients at less than goal
Once labs on day 2 suggest the formulation is okay the TPN is advanced toward goal
Starting the TPN at CHO goal can lead to high gycemic indices and low electrolyte values Chad Bradford. Touro University College of Pharmacy

**10. **Calculating Macronutrients Step 1: Determine the reference weight
Step 2: Determine the Total Calories
Step 3: Determine Protein Calories
Step 4: Determine Non-Protein Calories
Step 5: Determine the Lipid volume
Step 6: Determine the CHO Calories Chad Bradford. Touro University College of Pharmacy

**11. **Calculating Macronutrients Step 1: Assume the proper reference weight is 70 kg
Step 2: Recall that the Total Cal = 20-35 kcal/kg
Therefore: 70 kg x 25 kcal/kg = 1750 kcal
Step 3: Recall that the Protein/AA = 1-2 g/kg/d
Therefore: 70 kg x 1g/kg/d = 70 g/d
This value is in grams, but we need to convert it to kcal to determine the amount of the total calories that will come from a non-protein source.
Recall that Protein has 4kcal/g
Therefore: 70 g/d x 4 kcal/g = 280 kcal/d
Step 4: Determine the non-protein calories
Since we have the Total Calories and the Protein Calories the Non-Protein Calories are just the difference
Therefore: 1750 kcal - 280 kcal = 1470 kcal
The Non-Protein Calories come from the Lipids and Dextrose
Step 5: Recall that the Lipid = 10-25% with max of 2.5 g/kg/d
Therefore: 1470 kcal x 20% = 300 Kcal (approximately)
This value is in kcal, but we need to convert it to volume.
Recall that 20% Lipid has 2 kcal/mL
Therefore: 300 kcal x mL/2Kcal = 150 mL
Step 6: Recall that the CHO = Remaining portion of the Calories
Since we have the Non-Protein and Lipid Calories the CHO Calories are just the difference
Therefore: 1470 kcal 300 kcal = 1170 Kcal
This value is in kcal but we need to convert it to grams
Recall that CHO has 3.4 kcal/g
Therefore 1170 kcal x g/3.4 kcal = 344 g
Chad Bradford. Touro University College of Pharmacy

**12. **Calculating Volume New TPN Order
111g AA, 70g Lipid, 279g Dextrose
Final Volume: 2520mL Infused over 24 hours
Stock Supply: 10% AA, 20% Lipid, 50% Dextrose
Recall that 10% AA = 10g/100mL
Therefore 111g AA x 100mL/10g = 1110mL AA
Recall that 20% Lipid = 20g/100mL
Therefore 70g Lipid x 100ml/20g = 350mL Lipid
Recall that 50% Dextrose = 50g/100mL
Therefore 279g Dextrose x 100ml/50g = 558mL Dextrose
Total Volume = AA + Lipid + Dextrose
Therefore 1100mL + 350mL + 558mL = 2018mL
However this volume is less than the desired
Therefore we make up the remainder by adding sterile water
Total Volume Current Volume = The volume of sterile water to add
Therefore 2520mL - 2018mL = 502mL Sterile Water
Typically you add some overfill so the volume of sterile water with 100mL overfill would be 602mL bringing the total volume to 2620mL
Recall this TPN should be infused over 24 hours
Therefore 2520mL/24h = 105mL/h
Chad Bradford. Touro University College of Pharmacy

**13. **Calculating Cycle Changes New TPN Order
Currently 2520mL over 24 hours, change to 20 hour cycle
Step 1: Subtract the desired # of hours hour
Therefore 20 hours hour = 19.5 hours
This accounts for the hour taper up and down at the beginning and end of the TPN
Step 2: Divide total volume by the hours
Therefore 2520mL/19.5 h = 129mL/h
This is the infusion rate
Step 3: Multiply the infusion rate by the total hours 1
129mL/h x 19 = 2451mL
This is the amount infused over 19 hours
Step 4: Subtract the 19 hour volume from the total volume
2520mL - 2451mL = 69mL
This is the amount to infusion during the taper
The Order: Infuse 129mL/h for 19h with a 69mL/h taper at the beginning and end for 30 minutes
Check: 129ml/h x 19h = 2451, + 69mL = 2520mL Chad Bradford. Touro University College of Pharmacy

**14. **Calculating a TPN Order Total Volume: 1068mL/d including excess
Step 1: Calculate Macronutrients
The order is for 5% AA
5g/100mL = x/1068mL ? 53.4g AA
The stock is Aminosyn 10%
Therefore 10g/100mL = 53.4g/x ? 534mL Aminosyn 10%
The order is for 25% Dextrose
25g/100ml = x/1068mL ? 267g Dextrose
The Stock is Dextrose 70%
Therefore 70g/100mL = 267g/x ? 381mL Dextrose 70%
The total volume of macronutrients
534mL + 381mL = 915mL Chad Bradford. Touro University College of Pharmacy

**15. **Calculating a TPN Order Step 2: Calculate Micronutrients
The order is for 15mmol/L Phosphate
15mmol/L x 1.068L = 16.02mmol is needed
The stock is K Phos: 3 mmol phos/mL
Therefore 3mmol/ml = 16.02 mmol/x ? 5.34mL K Phos
The order if for 30mEq/L Potassium
30mEq/L x 1.068 L = 32.04mEq is needed
The stock is KCl: 2.0mEq/ml
However some potassium was added with the phosphate
5.34 ml K Phos x 4.4 mEq/mL = 23.50mEq K
The difference that needs to be added
32.04mEq 23.50mEq = 8.54mEq
Therefore 2.0mEq/ml = 8.54mEq/x ? 4.27mL KCL
This process is completed for all micronutrients, drugs, etc and any remaining volume at the end is met with the addition of sterile water
Chad Bradford. Touro University College of Pharmacy

**16. **Pharmacist Role Often TPN is ordered per pharmacy just like antibiotics and other drugs.
Pharmacists will then handle all aspects of TPN
Compounding, Dispensing, Monitoring, Adjusting, and Follow Up.
The majority of TPN calculations and compounding are done via automated systems
However in the event these systems become unavailable and a stat order is needed, it is important to know how to perform the calculations and compounding
Chad Bradford. Touro University College of Pharmacy

**17. **Questions ??? Chad Bradford. Touro University College of Pharmacy