1. Copyright © 2015 Cengage Learning® Chapter 4 Metric/International (SI) System

2. Copyright © 2015 Cengage Learning® Metric System /Système International (SI) Developed in France in 1875 Name stems from basic unit of measure –Meter 4-2

3. Copyright © 2015 Cengage Learning® Metric/SI System All units of measure differ from each other in powers of 10. Conversions between units accomplished by simply moving the decimal point. The greatest hazard of the metric system in drug dosages is that a misplaced decimal point will alter a dosage by a multiple of at least 10. 4-3

4. Copyright © 2015 Cengage Learning® Basic Units Length –Meter Volume –Liter Weight –Gram 4-4

5. Copyright © 2015 Cengage Learning® Terms Whether larger or smaller than basic units, all other units have name of basic unit incorporated in them: –For example, kilogram, centimeter, milligram, microgram So, the only units that can stand alone are meter, liter, and gram. If you have just m, then it is meter. You would have to have mm for millimeter. 4-5

6. Copyright © 2015 Cengage Learning® Abbreviations Gram (g) Milligram (mg) Microgram (mcg) Liter (L) which is always a capital L Milliliter (mL) Kilogram (kg) Kilometer (km) 4-6

7. Copyright © 2015 Cengage Learning® Now do in your notebook P. 37 Problems 4.1 P. 38 Problems 4.2 7

8. Copyright © 2015 Cengage Learning® Notation Rules 1.Quantity written in Arabic numbers: –1, 2, 3, 4, etc. –For example, 5 mL, 125 mcg, 11 cm, 62 kg, 35 mg 2.Numbers representing quantity placed before abbreviations: –For example, 3 mL, 10 kg, 6 mg, 250 mcg, 8 cm (continues) 4-8

9. Copyright © 2015 Cengage Learning® Notation Rules (cont’d) 3.Full space used between number and abbreviation: –For example, 10 mg, 100 L, 15 mcg 4.Fractional parts of unit written in decimal fractions: –For example, 34.5 mg, 2.5 mL, 78.2 kg (continues) 4-9

10. Copyright © 2015 Cengage Learning® Notation Rules (cont’d) 5.Zero placed in front of decimal point when not preceded by whole number: –Emphasizes decimal point –For example, 0.25 mg, 0.5 g 6.Excess zeros following decimal fraction deleted: –For example, 4.500 g = 4.5 g; 2.500 L = 2.5 L 4-10

11. Copyright © 2015 Cengage Learning® Now do in your notebook P. 39 Problems 4.3 11

12. Copyright © 2015 Cengage Learning® Common Weight Units Used in Health Care Kilogram Gram Milligram Microgram 4-12

13. Copyright © 2015 Cengage Learning® Common Volume Units Used in Health Care Liter Milliliter 4-13

14. Copyright © 2015 Cengage Learning® Metric Conversions Move decimal point three places when units of clinical measure differ by 1000. To convert 0.5 g to mL, move the decimal three places to the right. (continues) 0.5 g =.500. mg = 500 mg 4-14

15. Copyright © 2015 Cengage Learning® Metric Conversions (cont’d) k h dk B d c m Kilo Hecto Deka BASIC Deci Centi milli meter m liter L gram g To go from 1 mL to L, move the decimal three places to the left. (continues) 4-15 1 mL = 0.001. L = 0.001 L

16. Copyright © 2015 Cengage Learning® Metric Conversions (cont’d) When converting from smaller to larger units in same basic unit of measure, move decimal point three places to the left. –For example, weight Numerical answer will be smaller. (continues) 4-16

17. Copyright © 2015 Cengage Learning® Metric Conversions When converting from larger to smaller units in same basic unit of measure, move decimal point three places to the right. Numerical answer will be larger. 4-17

18. Copyright © 2015 Cengage Learning® Unnecessary Zeros Unnecessary zeros are eliminated when metric dosages are transcribed: 2.0 mg = 2 mg, 0.20 mg = 0.2 mg 4-18

19. Copyright © 2015 Cengage Learning® Now do in your notebook P. 40 Problems 4.4 P. 41 Problems 4.5 P. 42 Problems 4.6 19

20. Copyright © 2015 Cengage Learning® Errors Most errors occur because prescriptions are not properly notated or are inaccurately transcribed. Errors usually involve decimal fractions. 4-20

21. Copyright © 2015 Cengage Learning® Avoiding Errors Use reasoning powers. Question quantities that seem unreasonable. 4-21

22. Copyright © 2015 Cengage Learning® Now do in your notebook P. 44 Summary Self Test Practice Quiz on line Ready for the Chapter Test? 22