Question

RK is a 154 lb female with Hyperemesis Gravidarum [average daily emesis = 750ml] who has been ordered the following:

TPN @ 25Kcal/kg: 30% Kcal from Lipids, 1gm/kg from amino acids and the balance of calories from dextrose.

How would the pharmacist design the above TPN using 10% amino acids, 50% dextrose, 20% lipids and sterile water for injection? Using standards of care for pregnant patients [per Practical Gastroenterology-June 2008], fluid requirements during pregnancy are 30ml/kg plus an additional volume to replace that which is lost daily via emesis.

1. Calculate the maximum daily fluid requirements _______________________________________

2. Calculate total Kcal ____________________________________________

3. Calculate Kcal from lipids __________________________________________ a. Calculate the volume of lipids ________________________________________ b. Calculate the grams of lipids ________________________________________

4. Calculate the grams of amino acids per day _______________________________ a. Calculate the volume of amino acids _______________________________ b. Calculate the Kcal of amino acids __________________________________

5. Calculate the Kcal from dextrose ____________________________________________ a. Calculate the grams of dextrose per day ____________________________________ b. Calculate the volume of dextrose per day ____________________________________

6. Calculate volume of sterile water to “qs” to total daily fluid requirements __________________________________________

7. Calculate the infusion rate (in ml/hr) if the TPN is to be infused over 24 hours ___________________________________________

Answer 1

1lbs = 0.45 kg

154 lbs = 69.3 kg

1. Daily fluid requirement is 30 ml/kg + 750 ml (emisis loss)

So, 30*69.3 =2079+750 = 2829 ml

2. total calorie = 25kcal per kg = 25*69.3 =1732.5 kcal

3. calories from Lipids = 30% from lipid

total calories * 30/100= 1732.5*30/100 =519.75kcal

a, Volume of lipid = 20% of total solution= 2829*20/100=565.8ml

b grams of lipid = 30% of lipid in 565.8 ml =30*565.8/100 =169.74 gram

4. grams of amino acid per day

1 gm per kg = 1*69.3 = 69.3 gms of amino acid

a. volume of amino acid

b. calories of amino acid

4kcal/gm

69.3*4=277.2 kcal

5. calories from dextrose= total calories- amino acid calories-lipid calories

1732.5kcal-519.75kcal-277.2 kcal=935.55 kcal

a. Total kcal/3.4 kcal/gm= 935.55/3.4 kcal/gm=275.2 gms

b.

6.

7.infusion rate over 24 hrs= total volume/ 24 hr = 2829ml/24hrs =118 ml/hr