1. Dosage Calculations Using Dimensional Analysis
Anyone can do it!

2. Outcomes:
Understand the learning components needed for student success in performing dosage calculations.
Utilize dimensional analysis to calculate dosage.
Potential resources for teaching dimensional analysis in the classroom.

3. Ways to calculate dosage:
Formula Method
Amount to Give
Challenge: Must remember the extra step of changing D and H to same unit of measurement. Also may have extra variables such as body weight, times per day, etc.

4. Ways to calculate dosage:
Ratio and Proportion
Linear Ratio and Proportion
Fractional Ratio and Proportion
500mg : 1 tab :: 1 g : x tabs
Product of the means equals the product of the extremes.
The products of cross multiplication in a proportion are always equal

5. Dimensional Analysis
Dimensional Analysis involves setting up a series of fractions.
All information is in one problem
Students do not have to remember multiple steps
Students ask four simple questions to set up their dimensional analysis problem.

6. Necessities for Student Success in Dosage Calculations
Review of basic math functions – fractions and decimals
Adding
Subtracting
Multiplication
Division
Students must memorize equivalents

7. The 4 main questions What is the order? What is on hand?
Do you need any equivalents?
Where are you going? (or what are you being asked to give?)

8. Start with conversions
240 mg = ______ grains

9. Start with conversions
240 mg = ______ grains 4 4
grains 1

10. Order: Lasix 40 mg PO daily Dose on Hand: 80 mg/10 ml
What is the order?

11. Order: Lasix 40 mg PO daily Dose on Hand: 80 mg/10 ml
What is on hand?

12. Order: Lasix 40 mg PO daily Dose on Hand: 80 mg/10 ml
Do you need any equivalents?

13. Order: Lasix 40 mg PO daily Dose on Hand: 80 mg/10 ml
Where are you going? (or what are you being asked to give?)

14. Order: Lasix 40 mg PO daily Dose on Hand: 80 mg/10 ml
Begin by cross canceling labels

15. Order: Lasix 40 mg PO daily Dose on Hand: 80 mg/10 ml
Labels left should be “what you are looking for”

16. Order: Lasix 40 mg PO daily Dose on Hand: 80 mg/10 ml
Do the math 1 5 5 2 1

17. What about problems with different units of measurement?
Order: digoxin elixir 0.05 mg PO daily
Label: Digoxin 50 mcg per ml
How many milliliters will you give? 20 ml 1 1

18. Complex Problems
Order: Augmentin 12.5mg/kg PO every 12 hours. Child weighs 22 lbs. Pharmacy sends a 75 ml bottle of Augmentin labeled 125mg/5ml. How many milliliters will you pour from the bottle? 5 ml

19. 25 What about IV problems? Order: 250ml 5% D/W IV in 2.5 hours.
Tubing package reads 15 gtts/ml.
How many gtts/min will you adjust the IV? 25

20. Physicians order Daypro 1200 mg bid.
cap 1

21. Order: Estratab 1250mcg daily

22. The order reads: Administer 1000cc of D5NS over 10 hrs
The order reads: Administer 1000cc of D5NS over 10 hrs. The drop factor on your tubing is 15 gtts/cc. How many gtts/min? 25 1 25
gtts/min 4 or 1

23. Practice Problems

24. Your patient may receive Dilaudid 3 mg IM q3h for pain
Your patient may receive Dilaudid 3 mg IM q3h for pain. Dilaudid is supplied in 1-ml ampules containing 4 mg. How many milliliters will you administer?
¾= 0.75 ml

25. The physician orders heparin 2500U subq. You have heparin, 5000U per ml. How many ml will you administer? 1 ml 2

26. Your patient needs morphine gr 1/6 SQ stat for chest pain
Your patient needs morphine gr 1/6 SQ stat for chest pain. You have a 20 ml vial labeled 15mg/ml. How many milliliters will you give? ml
0.67

27. A patient with tachycardia has an order for Brevibloc to be started at 50 mcg/kg/min. The concentration is Brevibloc 5 g in 500ml of D5W. The patient weighs 176 pounds. How many ml/h should the IV pump be programmed for? 24
ml/hr 1 2 25 12 1 80 24 1 2 40 1 1 1

28. Resources for teaching Dimensional Analysis
IV Calculations site  
 Math tutorials  
 IV drip rate problems and dosage calculation problems  

29. Nursing Math Simplified “Math Magic” Author: Susan Garner Moore ISBN: page book – basics on what they call “Math Magic”

30. Quick & Easy Dosage Calculations
Quick & Easy Dosage Calculations: Using Dimensional Analysis
by: Christina Wu Nasrawi, Judith Ann Allender, Maura Conner
Product Details
Paperback: 318 pages ; Dimensions (in inches): 0.75 x x 8.50
Publisher: W B Saunders; 1st edition (February 15, 1999)
ISBN:

31. Clinical Calculation Made Easy
Clinical Calculations Made Easy: Solving Problems Using Dimensional Analysis : Softbound
By Gloria Craig
Edition: Second
ISBN:
Pub Date: February 2001
Pages: 272
Illustrations: 245

32. Medical Dosage Calculations
Medical Dosage Calculations June Looby Olsen, Leon J. Ablon, Anthony P. Giangrasso, Anthony Patrick Giangrasso
ISBN: Format: Paperback, 336pp Pub. Date: January 1995
Publisher: Benjamin-Cummings Publishing Company Edition Description: Older Edition

33. Dimensional Analysis for Meds
Dimensional Analysis for Meds Anna M. Curren, Laurie D. Munday
ISBN: X Format: Paperback, 319pp Pub. Date: November 2001
Publisher: Delmar Learning Edition Description: 2ND BK&CDR Edition Number: 2

34. Dosage Calculations
Dosage Calculations : A Simplified Approach Billie Ann Wilson, Billie E. Wilson, With Margaret T. Shannon
ISBN: X Format: Paperback, 219pp Pub. Date: December 1996
Publisher: Appleton & Lange Edition Description: 3rd Edition Edition Number: 3

35. Calculating Drug Dosages
Calculating Drug Dosages: An Interactive Approach to Learning Nursing Math Sandra Luz Martinez De Castillo, Sandra Luz Castillo, Maryanne Werner-McCullough
ISBN: Format: Other Format, 128pp Pub. Date: January 2002
Publisher: Davis F A Edition Description: BK&CD-ROM Edition Number: 1

36. Work with it and
Give it time
Try it - You'll like it!!