Dosage Calculations Using Dimensional Analysis Anyone can do it!
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.
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.
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
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.
Necessities for Student Success in Dosage Calculations • Review of basic math functions – fractions and decimals • Adding • Subtracting • Multiplication • Division • Students must memorize equivalents
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?)
Start with conversions 240 mg = ______ grains
Start with conversions 240 mg = ______ grains 4 4 grains 1
Order: Lasix 40 mg PO dailyDose on Hand: 80 mg/10 ml • What is the order?
Order: Lasix 40 mg PO dailyDose on Hand: 80 mg/10 ml • What is on hand?
Order: Lasix 40 mg PO dailyDose on Hand: 80 mg/10 ml • Do you need any equivalents?
Order: Lasix 40 mg PO dailyDose on Hand: 80 mg/10 ml • Where are you going? (or what are you being asked to give?)
Order: Lasix 40 mg PO dailyDose on Hand: 80 mg/10 ml • Begin by cross canceling labels
Order: Lasix 40 mg PO dailyDose on Hand: 80 mg/10 ml • Labels left should be “what you are looking for”
Order: Lasix 40 mg PO dailyDose on Hand: 80 mg/10 ml • Do the math 1 5 5 2 1
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
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
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
Physicians order Daypro 1200 mg bid. 2 2 cap 1
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
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? ml ¾= 0.75
The physician orders heparin 2500U subq. You have heparin, 5000U per ml. How many ml will you administer? 1 ml 2
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
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
Resources for teaching Dimensional Analysis IV Calculations site http://www.geocities.com/Heartland/Valley/3049/iv/clcltns.html Math tutorials http://www.utep.edu/nurs4710/tutorials/ IV drip rate problems and dosage calculation problems http://www.dalesplace.net/iv.htm
Nursing Math Simplified“Math Magic”Author: Susan Garner MooreISBN: 0-943202-22-153 page book – basics on what they call “Math Magic”
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 10.00 x 8.50 • Publisher: W B Saunders; 1st edition (February 15, 1999) • ISBN: 0721671330
Clinical Calculation Made Easy • Clinical Calculations Made Easy:Solving Problems Using Dimensional Analysis : Softbound • By Gloria Craig • Edition: Second • ISBN: 0-7817-3099-6 • Pub Date: February 2001 • Pages: 272 • Illustrations: 245
Medical Dosage Calculations • Medical Dosage CalculationsJune Looby Olsen, Leon J. Ablon, Anthony P. Giangrasso, Anthony Patrick Giangrasso • ISBN: 0805356053Format: Paperback, 336ppPub. Date: January 1995 • Publisher: Benjamin-Cummings Publishing CompanyEdition Description: Older Edition
Dimensional Analysis for Meds • Dimensional Analysis for MedsAnna M. Curren, Laurie D. Munday • ISBN: 076685938XFormat: Paperback, 319ppPub. Date: November 2001 • Publisher: Delmar LearningEdition Description: 2ND BK&CDREdition Number: 2
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Calculating Drug Dosages • Calculating Drug Dosages: An Interactive Approach to Learning Nursing MathSandra Luz Martinez De Castillo, Sandra Luz Castillo, Maryanne Werner-McCullough • ISBN: 0803605781Format: Other Format, 128ppPub. Date: January 2002 • Publisher: Davis F AEdition Description: BK&CD-ROMEdition Number: 1
Work with it and Give it time Try it - You'll like it!!