Calculations III

Question 1

What are the 2 different types of parenteral nutrition? What USP chapter must PN preparation comply with? What does PN require during administration?

Answer 1

2-in-1 formulations: contain dextrose and amino acids

3-in-1 formulations: contain dextrose, amino acids, and lipids (also called TPN)

These must comply with USP Chapter 797

PN requires a filter due to the risk of precipitate. Also, a central line is preferred, but if only doing < 1 week of PN, you could technically do a peripheral line (but there’s risk of phlebitis).

Question 2

What is the daily fluid requirement formula?

Answer 2

when weight < 20kg: 1500mL + (20mL)(weight in kg - 20kg)

Question 3

According to the Harris, Benedict equations, do men and women have the same basal energy expenditure? What is the difference between basal and total energy expenditure? What is the equation to calculate TEE?

Answer 3

No, BEE is calculated differently for males and females.
- can be estimated around 15-25kcal/kg/day

TEE is basal energy expenditure + excess metabolic demands.

TEE = BEE x activity factor x stress factor

Question 4

how many calories come from 1g of carbs, fat, and protein?

Answer 4

1g of carbs = 4kcal

1g of fat = 9kcal

1g of protein = 4kcal

Question 5

how many calories come from 1g of dextrose monohydrate, glycerol/glycerin?

Answer 5

dextrose monohydrate = 3.4kcal/gram

glycerol/glycerin = 4.3kcal/gram

Question 6

how many calories come from 1 mL of injectable lipid emulsion 10%, 20%, and 30%?

Answer 6

injectable lipid emulsion 10%: 1.1kcal/mL

injectable lipid emulsion 20%: 2kcal/mL

injectable lipid emulsion 30%: 3kcal/mL

Question 7

how many calories come from 1 gram of amino acid solutions?

Answer 7

amino acid solutions: 4kcal/gram

Question 8

what is the typical protein requirement for ambulatory, non-hospitalized people vs. hospitalized or malnourished people?

Answer 8

ambulatory, non-hospitalized: 0.8-1g/kg/day

hospitalized or malnourished: 1.2-2 g/kg/day

Question 9

How many grams of protein is received by a patient per 1g of nitrogen released? What is the equation to determine nitrogen intake?

Answer 9

1g of nitrogen is released for each 6.25g of protein

Nitrogen intake = grams of protein intake/6.25

Question 10

How do you find the non-protein calories to nitrogen ratio?

Answer 10

1. calculate gram of nitrogen supplied per day (1g N = 6.25g protein)
2. divide total non-protein calories (dextrose + lipids) by the grams of nitrogen

Question 11

What macronutrient are these products: Aminosyn, FreAmine, Travasol, TrophAmine, Clinisol

Answer 11

these are all amino acid products. they call provide 4kcal/g

Question 12

what preparation on sodium should be added to PN if the patient is acidodic?

Answer 12

sodium acetate should be used because it is converted to sodium bicarbonate

Question 13

What is the corrected calcium equation?

Answer 13

corrected calcium = serum calcium + [(4.0-albumin)x0.8]

Question 14

What are 4 steps to reduce the risk of calcium-phosphate precipitate?

Answer 14

1. choose calcium gluconate over calcium chloride (gluconate has a lower risk of precipitation)
2. add phosphate first, then add calcium near the end to take advantage of the maximum volume of the PN formulation
3. the calcium and phosphate added together should not exceed 45mEq/L
4. maintain proper pH and refrigerate the bag once opened

Question 15

what is the general rule for preventing drug/enteral feeding interactions?

Answer 15

hold the feeds 1 hour before and 1-2 hours after drug administration

• warfarin: hold 1 hour before and 1 hour after warfarin
• tetracyclines, quinolones, levothyroxine: separate from tube feeds
• ciprofloxacin: immediate-release tablets are used. crush and mix with water
• phenytoin: levels are reduced when drug binds to the feeding solution, so separate tube feeds by 2 hours