Dose Calculation

Changed
Sat, 07/06/2024 - 18:31

Dose Calculation

By a a on Sun, 01/01/2023 - 22:57

Metric system prefixes come before a basic unit of measure to indicate a multiple (or submultiple) of that unit.

Basic metric units and what they measure include:

  • meter (length)
  • gram (mass)
  • liter (volume)
  • second (time)

 

Conversion within the metric system -common conversion factors
K-kilo H-hecta D-deca

Unit Measure

  • Meter (length)
  • Gram (mass)
  • Liter (volume)
 D-deci- C-centi- M-milli-
1 0 0 0 0 0 0
  1 0 0 0 0 0
    1 0 0 0 0
      1 0 0 0
        1 0 0
          1 0
            1

 

In the metric system, Latin prefix denotes fractions of the basic unit under consideration:

  • Deci = one tenth
    • one decimeter = 0.1 meter
  • Centi = one hundredth
    • one centimeter = .01 meter
  • Milli = one thousand
    • one millimeter = .001 meter

Common Metric Abbreviations

  • gram = g
  • milligram = mg
  • kilogram = kg
  • liter = L
  • milliliter = mL
  • microgram = mcg

To convert a smaller unit to a larger one, divide by moving the decimal point places to the left.

Example:

100 mL = ____ L (conversion factor)

(smaller) ------------(larger)

1000 mL = 1 L

 

100 mL = .100 = 0.1 L

To convert a larger unit to a smaller one, multiply by moving the decimal places to the right.

Example:

0.75 grams = _____mg (conversion factor)

(larger) (smaller) 1 g = 1000 mg

 

.75 g = .750 = 750 mg

 

Apothecary and Household Units of Measure

The basic unit for weight for the apothecary system is the grain.

Very important to remember that grain is appreciated as gr and gram is abbreviated as g.

Two important conversions to remember are gr 15 = 1 g and 60 mg = 1 gr.

The unit of liquid measure is a minim, which is the amount of water that would weigh a grain.

The household system is basically used at home. It is still important for the nurse to be familiar with this system especially if you work in pediatrics or home care. The household method is the least accurate of the three systems.

 

Household Units of Measure

  • 1 teaspoon (tsp) = 5 mL
  • 1 tablespoon (tbsp) = 15 mL
  • 1 teaspoon = 60 gtts
  • 4 teaspoons = 1 tablespoon
  • 1 cup = 8 0z or 240 mL
  • 2 cups = 1 pint
  • 2 pints = 1 quart
  • 4 quarts = 1 gallon
  • 16 ounces = 1 pound
  • 2.2 lb = 1 kg (1000 g)

 

Tags
Dose Calculation
Apothecary
Metric system

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