1. Math for Clinical Practice
Units of Measure
Math for Clinical Practice

2. Weight
Kilogram = kg
Gram = g
Milligram = mg
Microgram = mcg

3. Length
1 meter = m
Centimeter = cm
Millimeter = mm

4. Volume 1 liter = L 1 milliliter = mL or cc
(cc is not to be used anymore according to JACOH standards but it is a common error since it has been used for years)
CC = mL

5. Length 1 meter (m) = 100 cm or 1000 mm Centimeter (cm) = 10 mm
Millimeter (mm) = 0.1 cm

6. Household Abbreviations
1 ounce or oz
Tablespoon = Tbs
Teaspoon = tsp or t

7. Conversion of Metric Units

8. Household Measurement
1 ounce (oz) = 30 mL
1 tablespoon (Tbs) = 15 mL
1 teaspoon (tsp) = 5 mL

9. Ounces to mL
You are doing intake and output and the mother states the infant has consumed 3 ½ ounces of formula. How many mL has the infant consumed?
3.5 x 30 mL = 105 mL
You would record 105 mL on the intake record

10. Measuring Liquids

11. Tablespoons
You are teaching a geriatric patient how to measure her medications. She is to take 15 mL of liquid Maalox to aid digestion.
You would instruct her to use what household measuring device to take her mediation?
Teaspoon or tablespoon
She would take one tablespoon of medication.

12. Teaspoon
You are working with a mother of a toddler and she has been instructed to give the child 1 ½ teaspoons of medication. You are demonstrating how to give the medication with a syringe with measurements in mL.
How many mL would you have her give?

13. 1 Teaspoon = 5 ml 1 ½ teaspoons = 1.5 teaspoons
1.5 teaspoon x 5 mL = 7.5 mL
You would have her draw up 7.5 mL in a po syringe.

14. Nursing Alert
Remember if there is not a number to the left of the decimal point a zero is placed there to highlight the decimal point placement.
Correct: 0.5 mL or 0.25 g
Incorrect: 5.0 mL or 25.0 g

15. Nursing Alert
Decide whether you are converting from smaller unit to larger unit or larger unit to smaller unit.

16. Liter to milliliters 1 liter (L) = 1000 milliliters (mL)
1.2 x 1000 = 1200 mL

17. Milliliters (mL) to Liters (L)
Change mL to Liter (L)
mL is smaller than a liter
Move decimal point three places to the right
750 mL = 0.75 L

18. Metric Units Weight Kilogram = kg 1 kg = 1000 grams (g)
1 gram (g) = 1000 milligrams (mg)
1 milligram (mg) = 1000 micrograms mcg

19. How to calculate kilograms
Remember you will weigh less in kilograms
To convert pounds to kilogram you divide by 2.2
Convert 100 pounds to kg
100 / 2.2 = or 45.45
In the infant / small child carry out to the 100th or two decimal places.

20. Example Convert the following metric measurement: 0.2 mg = ______ g.
(gram is larger than a mg)
Need to move the decimal 3 places or divide by 1000.
Answer 0.2 mg = g

21. Example
100 mcg = ______ mg
You are going from a smaller unit to a larger unit.
You would move the decimal point 3 places or divide by 1000.
100 mcg = 0.1 mg

22. International and Milliequivalent Measures

23. International Units
Heparin, insulin, penicillin, epoetin products (Epogen, Procrit) are measured in international units.
Example: regular insulin 10 units SQ in am
Example: penicillin 600,000 units IM x one dose

24. Milliequivalent Measures
Do not confuse with milligrams.
Notation is mEq
Milliequivalent measures the number of grams of equivalent weight of a drug contained in 1 mL of normal saline.

25. mEq
Common drugs: sodium bicarbonate, sodium chloride, potassium chloride.
Examples:
10 mEq of potassium chloride to ½ L of IV solution
15 mEq of sodium chloride to 1 L of IV solution

26. Conversions

27. Conversions
Clinical connection: often you need to calculate between different systems of measure.

28. Metric System Metric System 1 kg = 1000 g 1 g = 1000 mg
1 mg = 1000 mcg
1 L = 1000 mL

29. Grains 60 mg = 1 gr 45 mg = ¾ gr 30 mg = ½ gr 15 mg = ¼ gr

30. Conversion to Metric Equivalents
60 mg
gr1
45 mg
Gr 3/4
gr 1/4
15 mg
gr 1/2
30 mg

31. Practice Problems gr ¾ = ___________ mg gr ¼ = ___________ mg

32. Practice problems
The bottle of Tylenol states that you are to give X (ten grains) of Tylenol.
How many mgs are you giving ________

33. Chapter Review

34. Calculations in the Clinical Setting

35. Ratio – Proportion Method
Using the ratio proportion method offers a systematic approach to solving clinical math calculations.

36. The Set-up Solving the unknown The cookies and the eggs
If the recipe states you need 2 eggs to make 2 dozen cookies. How many eggs do you need to make a dozen cookies?
24 cookies 12 cookies
2 eggs = x eggs

37. Practice Problem Page 106 Lorazepram 3 mg IV every 6 hours as needed.
Lorazepam is supplied as 4 mg / mL

38. The set-up 4 mg 3 mg 1mL = x mL (cross multiply) 3 / 4 x = 0.75 mL
You would draw up 0.75 mL to equal 2 mg of Lorazepam

39. Practice Problem Page 108 Phenytoin sodium 300 mg by mouth at bedtime.
Phenytoin sodium supplied as 125 mg / 5 mL.

40. The Set-up
125 mg 300 mg
5 mL = x mL
(Cross multiple) (X is on the bottom)
1500
125 X = 12 mL equals 300 mg of the drug

41. Practice Problems
Remember to label properly and put the x on the bottom.

42. Body Weight

43. Review Pounds to kilograms Pounds divided by 2.3
Practice problems 1-10 page

44. Practice Problem Neupogen 5 mcg/kg/day IV over 30 minutes.
Patient weight = 174

45. Change Pounds to Kilograms
174 / 2.2 = kg

46. Determine the dosage 5 mcg / kg / day
5 mcg x (weight in kg) = mcg per dose
Drug is rounded to 395 mcg per dose to be added to 50 mL of Dextrose 5% in Water.

47. Practice Problem
Phenobarbital 30 – 120 mg / kg per day in 3 divided doses
Physician orders the maximum dose or 120 mg / day to be given q 8 hours.
1st you would need to divide 120 mg by 3 doses = 40 mg per dose

48. Determine the Amount Phenobarbital is provided as 65 mg / mL
For one dose you would need to draw up how much of the medication?
40 mg = 60 mg
x mL 1 mL
40 mg = mL
60 x