Bedside TPN: The Practicing Surgeon
B Phillips
Keywords
medicine, nutrition, parenteral nutrition, pharmacology, tpn
Citation
B Phillips. Bedside TPN: The Practicing Surgeon. The Internet Journal of Pharmacology. 2000 Volume 1 Number 1.
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
e.g. 76 kgs x 1.5 g/kg/day
114 g protein/day Needed
3. Calculate NonProtein Calories
e.g. 76 kg x 25 kcal/kg/d
1900 kcal/day Needed
4. Determine CHO:Lipid Ratio
estimate need based on patient disease
e.g. 1900 kcal/day Needed from NonProtein Calories

70 % CHO = 1330 kcal/day from CHO

30 % Lipids = 570 kcal/day from Lipids
5. Now, Calculate Grams Needed & ml of Solution
a.
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.
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
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. NonProtein Calories Needed
D.CHO:Lipid Ratio

Grams CHO / Day Needed (& ml of Solution)

Grams Lipid / Day Needed (& ml of Solution)
E. Total Volume Requirements
F. Rate of Infusion
G. Total Calories Provided & Percentage of Each Category

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