Computation of TPN

TPN

1st Compute for BEE ( Basal energy expenditure) of the patient using Harris-Benedict Equation

MaleBEE= 66.67 +[13.75 x wt (kg)] +

[5 x ht(cm)] – [6.76 x age in yrs]

TPN

• FemaleBEE = 655.1 + [9.56 x wt kg] +[1.86 x ht(cm)] – [4.68 x age in yrs]

Answer for BEE will be in Kcal (kilocalories)

TPN

• 2nd Compute for TDE• TDE = BEE x Activity factor x Stress factor• Ref to page 111 of your lab manual for the

different values to be used depending on the case of the patient. If the patient is unstressed, use 1 as the stress factor

TPN

• 3rd Compute for The protein, lipid, and carbohydrate requirement of a patient based on the computed TDE• Refer to page 111 of your lab manual

TPN

• Proteins• 1 g of protein will yield 4kcal• Your source of protein will most likely be an

amino acid (AA) solution

TPN

• Lipid• Kcallipids must be 30% - 40% of the TDE• 1 g of lipid will yield 9 kcal but our source of

lipids is in the form of emulsion so:• 10% lipid emulsion yields 1.1 kcal/mL• 20% lipid emulsion yields 2 kcal/mL• 30% lipid emulsion yields 3 kcal/mL

TPN

• Carbohydrates• Kcal supplied by carbohydrates can be

computed using the formula• Kcalcarb = TDE –(Kcalproteins + Kcallipids)

• Determine the amount of carbohydrates to be added to the TPN in order to supply the necessary Kcal from carbohydrates as computed using the formula above.

• This can be done by computing how much grams of carbohydrates are equal to the computed Kcal.

• Take note that 1 g of dextrose will yield 3.4 kcal, while 1 g of glucose will yield 4 kcal.

• The usual source of carbohydrate is dextrose• D5W, D15W, D20W, D50W• The amount of dextrose in mL to be used

should also be determined

• 4th The fluid requirement of the patient is computed by using 1.2mL/Kcal of TDE

• The fluid requirement of your patient is the FINAL volume of your TPN.

• Using the volume required to supply your proteins, lipids, and carbohydrates, check if their total will be less than, more than, or equal to the fluid requirement of the patient.

• If it is less than, the remaining volume to make the final volume will be supplied by SWFI.

• If it is more than, change your source of proteins, lipids, or carbohydrates to a more concentrated one. .

Sample Problem

• A 30 year old male severely burned patient is to be administered with TPN. The patient weighs 80 kg and stands 5’8”. Prepare a TPN solution based on the patient needs. Use upper limit for requirement expressed in ranges. Compute for the amount of 30 % lipid emulsion, 8.5 % AA solution, D50W, and SWFI to be used for the preparation of TPN.

• The patient is male, weight is 80 kg, height is 5’8”= 172.72 cm, age is 30 years.

• BEE= 66.67 +[13.75 x wt (kg)] + [5 x ht(cm)] – [6.76 x age in yrs]

• BEE = 66.67 + (13.75 x 80) + (5 x 172.72) – (6.76 x 30)• BEE = 1827.47 Kcal• TDE = BEE x AF x SF• Activity factor is 1.2 for confined patient since the

patient is already taking TPN (refer to page 111 of your lab manual)

• The patient is severely burned. Referring to page 111 of your lab manual, burned patients will have a SF from 1.5 to 2.1. The problem states that the pharmacist need to use the upper limit of any requirement expressed in ranges. So for this case, use 2.1 as your SF.

• TDE = BEE x 1.2 x 2.1• TDE = 1827.47 Kcal x 1.2 x 2.1• TDE = 4605.22 Kcal

• Protein requirement• The patient is severely burned so his protein

requirement will be 3 g /kg. The patient weighs 80 kg.

• 3g/kg x 80 kg = 240 g• 1 g of protein will yield 4 Kcal• 240 g x = 960 Kcal

• Your protein source is 8.5 % AA solution.• 8.5 % = , the patient needs 240 g of protein• 240 g x = 2823.53 mL of 8.5 % AA solution to

be added to your TPN

• Lipids• The range for lipid requirement of the patient is 30 –

40 %, since you need to use the upper limit for this patient, 40 % will be utilized.

• 40 % of TDE• 4605.22 Kcal x 0.4 = 1842.09 Kcal from Lipids• The source is 30 % lipid emulsion which yields 3

kcal/mL• 1842.09 Kcal x = 614.03 mL of 30 % lipid emulsion to

be added to your TPN.

• Kcalcarbohydrates = TDE – (Kcalproteins + Kcallipids)

• Kcalcarbohydrates = 4605.22 – (960 + 1842.09)

• Kcalcarbohydrates = 1803.13 Kcal from carbohydrates

• Your source is D50W = • 1 gram of dextrose will yield 3.4 Kcal• 1803.13 Kcal x = 530.33 g of dextrose• 530.33 g x = 1060.66 mL of D50W to be added to

your TPN

• Fluid requirement = • Fluid requirement = x 4605.22 Kcal• Fluid requirement = 5526.26 mL, this should

be the final volume of your TPN

• Adding all the volume of protein, lipids, and carbohydrates to be added to the TPN, we now have

• Protein = 2823.53 mL• Lipids = 614.03 mL• Carbohydrates = 1060.66 mL• 2823.53 mL+614.03 mL+1060.66 mL = 4498.22 mL

which is less than the fluid requirement of the patient, so the remaining volume should be added to make 5526.26 mL

• 5526.26 mL – 4498.22 mL = 1028.04 mL• 1028.04 mL is the volume of SWFI to be added

to make 5526.26 mL.

Selected problems from Exercise 15

• Page 116 no. 4• Solution:• AA source is 8.5 % solution• 2.125 % = x 1000 mL = 21.25 g• 21.25 g x = 250 mL

• For dextrose, your source is D50W• 20 % = 200 g• 200 g • For SWFI• 1000 mL – 250 mL – 400 mL = 350 mL

• # 6• Solution for NaCl 30 mEq; source 20 mL vial of

15% solution; 15 % = , NaCl has molecular weight of 58 g. Valence of Na is + 1and for Cl, -1.

• mEq = • mg = • mg = = 1740 mg = 1.74 g x = 11.6 mL