Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 1

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 2 Chapter 4 Comparisons of Measurement Systems

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 3 Learning Objectives Know the standard abbreviations for the household, metric, and apothecary systems used in the medical field Identify and use the household measurements of length, weight, and volume in the medical field Identify and use the International System of Units (SI), or metric, measurements of length, weight, and volume in the medical field Identify and use apothecary system measurements of weight and volume in the medical field

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 4 Common Measurement Systems Household or U.S. customary Metric Apothecary

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 5 Household Measurement System Based on English system of measures Expressed as Arabic numbers preceding abbreviations (e.g., 5 inches)

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 6 Household Measurements of Weight Measurement UnitAbbreviationEquivalents ounceoz— poundlb, #16 oz tonT2000#

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 7 Household Measurements of Length Measurement UnitAbbreviationEquivalents inchesin, ”— footft, ’12 inches yardyd36 inches, 3 feet

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 8 Household Measurements of Volume Measurement UnitAbbreviationEquivalents dropsgtts— teaspoonTsp, Tsp, t60 drops (depending on the size of the dropper and the viscosity of the medication) tablespoontbsp, Tbsp, tbs, T36 inches, 3 feet ounceoz2 tbsp or 6 tsp cupC, c8 oz pintpt2 c, 16 oz quartqt2 pt, 4 c, 32 oz gallongal4 qt, 8 pt, 16 c, 128 oz

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 9 Solving for Unknown Household Measures Using Proportion 2 feet 1½ inches = ? inches

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 10 Solving for Unknown Household Measures Using Fractions and Cross- Multiplication 2 feet 1½ inches = ? inches

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 11 Metric System of Measurement Most common Based on units of 10 Prefixes denote multiples (e.g., deci- is 1/10 the base, deka- is 10 times the base) Expressed as Arabic numerals preceding abbreviations (e.g., 10 mg)

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 12 Metric System of Measurement (cont’d.) UnitsWeightVolumeLength Basic unitgram (G, g, gm, GM)liter (L, l)meter (M, m) 1000 unitskilogram (kg, kG)kiloliterkilometer (km) 100 unitshectogram*hectoliterhectometer 10 unitsdekagramdekaliterdekameter 1/10th unitdecigramdeciliterdecimeter 1/100th unitcentigramcentilitercentimeter (cm) 1/1000th unitmilligram (mg, mG)milliliter (ml, mL) millimeter (mm) 1/1,000,000th unit microgram (mcg)microlitermicrometer (mcm) *The measurements found in tialics are those that are not commonly used in calculating pharmaceutical dosages in heights, weights, or volumes. Measurements with abbreviations are those that are commonly used in pharmacology.

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 13 Equivalents in the Metric System Type of SubstanceAbbreviation Unit of Measure Common Equivalents Volume/LiquidL, lliter1000 mL, 1000 cc mL, ml, ccmilliliter, cubic centimeter* L WeightG, g, gm, Gmgram1000 mg, kG kG, kgkilogram1000g mG, mgmilligram0.001 gm, 1000 mcg mcgmicrogram gm, mg LengthM, mmeter100 cm, 1000 mm cmcentimeter0.01 m, 10 mm Mmmillimeter0.001 m, 0.1 cm *A cubic centimeter (cc) is another way to express a milliliter. A cubic centimeter is the amount of space that is required to hold a milliliter of liquid.

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 14 Calculating Metric System Equivalents 1.2 L = ____ mL 5 mg = ____ g

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 15 Converting Metric Measures Using the Mnemonic

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 16 Converting Metric Measures Using the Mnemonic (cont’d.)

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 17 Apothecary System of Measurement Least common Expressed as abbreviations preceding: Lowercase Roman numerals with overhead lines, for quantities under 10 Arabic numerals, for quantities over 10, except 20 and 30 Based on minim for volume and grain for weight. Minims are not used today and only a few medications are measured in grains, such as, nitroglycerin and aspirin.

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 18 Equivalents in the Apothecary System Type of SubstanceAbbreviation Unit of Measure Common Equivalents Volume/Liquidminim— flfluid dram ix (60) flfluid ounce viii (8) Massgrgrain— dramgr ix (60) ounce viii (8) #pound xii (12)* *Note that in the apothecary system a pound is only 12 ounces.

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 19 Converting Apothecary Measures

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 20 Summary Three common measurement systems Household Metric Apothecary

Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 21

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Elsevier items and derived items © 2007 by Saunders, an imprint of Elsevier Inc Slide 24