UNIT 4 The Metric System

Key Terms Gram Liter Meter

Metric System First proposed in 1670 by Gabriel Mouton Adopted in 1801 by French National Assembly Official standard for scientific and industrial measurement in 92% of world Measured in units of 10 Utilizes concept of decimal point (continues)

Metric System Provides simple, flexible, accurate way to measure length, volume, and weight Medication dosages may be In micrograms In milligrams In grams Per kilogram of body weight (continues)

Metric System Volume of medication may be in Other measurements Milliliters Cubic centimeters Other measurements BP measured in millimeters of mercury (mm Hg) Wound and lesion size measured in centimeters Organs measured in grams (continues)

Metric System Laboratory results measured in: Micrograms Milligrams Grams per deciliter Units per liter

Basic Rules Whole numbers designated by Arabic numbers Decimal fractions used for numbers less than 1 Prefixes written in lowercase Abbreviations are same for singular or plural

Metric System Uses 14 prefixes Each prefix based on multiple of 10 Medical field uses seven most common prefixes

Metric Prefixes Micro- One millionth Milli- One thousandth Centi- One hundredth Deci- One tenth Deka- Ten Hecto- One hundred Kilo- One thousand

Fundamental Units Meter Length Liter Volume Gram Mass/Weight

Length Meter is fundamental unit of length 1 meter = 39.37 inches or 3.28 feet 1 inch = approximately 2.5 centimeters

Length Meter (m) Length 1 millimeter (mm) 0.001 meter 1 centimeter (cm) 0.01 meter 1 decimeter (dm) 0.1 meter 1 meter (m) 1 meter 1 dekameter (dam) 10 meters 1 hectometer (hm) 100 meters 1 kilometer (km) 1,000 meters

Volume Liter is fundamental unit of volume 1 liter = 1.056 quarts 1 liter = 0.26 gallon 1 liter = 2.1 pints 1 mL = 1 cc (continues)

Volume Liter is fundamental unit of volume (cont’d) Amount of space occupied by 1 milliliter is equivalent to 1 cubic centimeter 1 mL water = 1 g in weight 15 mL = 1 tablespoon

Volume Liter (L) Volume 1 milliliter (mL) 0.001 liter 1 centiliter (cL) 0.01 liter 1 deciliter (dL) 0.1 liter 1 liter (L) 1 liter 1 dekaliter (daL) 10 liters 1 hectoliter (hL) 100 liters 1 kiloliter (kL) 1,000 liters

Weight Gram is fundamental unit of solids, mass, or weight 1 cc or 1 mL of water = 1 g 1 g = approximately 15 grains 1 g = 0.035 oz

Weight Gram (g) Weight 1 milligram (mg) 0.001 gram 1 centigram (cg) 1 decigram (dg) 0.1 gram 1 gram (g) 1 gram 1 dekagram (dag) 10 grams 1 hectogram (hg) 100 grams 1 kilogram (kg) 1,000 grams

Common Equivalents 2 ½ cm = 1 inch 1,000 mL or cc = 1 liter 1,000 mcg = 1 mg 1,000 mg = 1 g 1,000 g = 1 kg 1 kg = 2.2 lb

Conversions Set up proportion using metric equivalents Assign x as value of unknown factor Solve proportion as learned in Unit 3

Moving the Decimal If converting from larger to smaller, multiply by decimal value of smaller unit (move decimal right) If converting from smaller to larger, divide by decimal value of smaller unit (move decimal left)

Dosage Based on Body Weight Some medications are ordered as mg/kg Weight of patient must be expressed in kg

Calculating Dose Convert weight to kg Calculate dosage based on weight Determine number of doses per day Calculate amount of medication per dose