Abstract

We present an easy way to calculate the requirements and components of a total parenteral nutrition TPN.

1. Calculate IBW (Ideal Body Weight)

Male: 106 lbs for the first 5’ & 6 lbs per inch after

Female: 100 lbs for the first 5’ & 5 lbs per inch after

e.g. 5’10” male - 106 + 60 = 166 lbs (now divide by 2.2 lbs/kg) = 75.5 kgs

2. Calculate Protein Need

1 g/kg/day - Non-Stressed

1.5 g/kg/day - Stressed

2.0 g/kg/day - Severe Stress

e.g. 76 kgs x 1.5 g/kg/day

114 g protein/day Needed

1 g Protein = 4 kcal Energy

114 g/day x 4kcal/g

456 kcal/day from protein

3. Calculate Non-Protein Calories

25 kcal/kg/day - Non-Stressed

30 kcal/kg/day - Stressed

35 kcal/kg/day - Severe Stress

e.g. 76 kg x 25 kcal/kg/d

1900 kcal/day Needed

4. Determine CHO:Lipid Ratio

65 % CHO - 35 % Lipids

70 % CHO - 30 % Lipids

75 % CHO - 25 % Lipids

80 % CHO - 20 % Lipids

estimate need based on patient disease and co-morbidities ! (remember, CO2 may not be a good thing)

e.g. 1900 kcal/day Needed from Non-Protein Calories

• 70 % CHO = 1330 kcal/day from CHO

• 30 % Lipids = 570 kcal/day from Lipids

5. Now, Calculate Grams Needed & ml of Solution

a. 1 g CHO = 3.4 kcal energy

e.g. 1330 kcal/day Needed from CHO

1330 / 3.4 = 391 g CHO/day needed

• By using a D50 Solution (500 g CHO/ Liter), you can

• multiply the number of grams needed by 2, to determine

• how many ml needed (same as dividing by 0.5)

• Divide by 0.7 if using a D70 Solution

e.g. 391 g Needed = 782 ml, D50 Solution

or

= 559 ml, D70 Solution

b. 1 g Lipids = 9 kcal energy

e.g. 570 kcal Lipids Needed/day = 63 g Lipids Needed/day

• If using a 20 % solution, 1 cc = 2 kcal energy

• If using a 10 % solution, 1 cc = 1 kcal energy

take the # kcal needed and divide by 2, to determine the number of ml of a 20 % lipid solution

e.g. 570 kcal/day needed = 285 cc of a 20 % Lipid Soln.

(29 cc/hr x 10 hrs)

6. Calculate Total Fluids Needed

Usual Estimate: 25 - 35 cc/kg/day (a thousand different formulas to choose from, just pick one and know how to use it)

e.g. 76 kg Male, 30 cc/kg/day Fluid = 2280 cc/fluid/day

• Subtract Lipid Amount from Total

(this is administered separate from the TPN Soln)

e.g. 2280 cc - 285 cc = 1995 cc TPN + Fluid/day

• Add Free Water to Make up the Difference

• Divide Total Volume by 24 hours to determine Hourly Rate

e.g. 1995cc / 24 hrs = 83 cc TPN Soln. / hr

7. Summarize Calculations

A. IBW

B. Protein Need :

# Grams # Calories Provided

C. Non-Protein Calories Needed

D.CHO:Lipid Ratio

1. Grams CHO / Day Needed (& ml of Solution)

2. Grams Lipid / Day Needed (& ml of Solution)

E. Total Volume Requirements

F. Rate of Infusion

G. Total Calories Provided & Percentage of Each Category

Some Other Points

• Na (2 mEq/kg/day)

• Cl (2 mEq/kg/d)

• K (1 mEq/kg/d)

• Ca (0.3 mEq/kg/d)

• Mg (0.4 mEq/kg/d)

• MVI

• Trace Elements

• Additional Supplements ?

• Accuchecks / Insulin Coverage

• Zantac / Cimetidine ?

• Begin TPN by Scaled Steps

• Discontinue TPN Abruptly (why “wean tpn” ?)

• Follow Electrolytes