Basic Calculations for Medical Assistants

Chapter Introduction Objectives

• Understand key skills and knowledge base for medical calculations

Objectives:

1. Glossary Definitions

   • Spell and define all words in this chapter using the glossary.

2. Basic Calculation Skills

   • Explain how to perform basic calculations necessary for medical assistants.

3. Mathematical Equations

   • Solve various mathematical equations used in medical settings.

4. Metrics and Household Measurement Units

   • Define and understand basic units of measurement in both metric and household systems.

5. Conversion Between Measurement Systems

   • Convert measurements between household and metric systems.

6. Abbreviations and Symbols

   • Identify common abbreviations and symbols used in medication dosage calculations.

Skills Acquired:

• Ability to calculate correct dosages of medication.

Words to Know

• Decimals: Numeric values that contain a decimal point.

• Denominator: The bottom number in a fraction.

• Dividend: The number to be divided in a division problem.

• Divisor: The number by which another number is divided.

• Extremes: The outer numbers in a proportion.

• Fraction: A part of a whole expressed as a numerator over a denominator.

• Improper Fraction: A fraction where the numerator is larger than the denominator.

• Means: The inner numbers in a proportion.

• Metric System: A decimal-based system of measurement.

• Mixed Fraction: A whole number combined with a fraction.

• Numerator: The top number in a fraction.

• Percentage: A ratio expressed as a fraction of 100.

• Product: The result of multiplying numbers.

• Proportion: An equation stating that two ratios are equal.

• Ratio: A relationship between two numbers, often expressed as a:b.

• Systems of Measurement: Different frameworks for quantifying variables (metric, household, apothecary).

The Metric System

• Importance: The primary system of measurement in medicine.

• Base Units:

  • Gram (g): For mass/weight.

  • Liter (L): For volume/liquid.

  • Meter (m): For length/size.

• Usage of Prefixes: To indicate multiples or submultiples (e.g., kilo- means 1,000).

• Common Prefixes in Metric System: Include micro-, milli-, centi-, deci-, deka-, hecto-, kilo-.

Household Measurements

• Common household measurements patients use at home:

  • Drop (GTT)

  • Teaspoon (t/TSP)

  • Tablespoon (T/TBS)

  • Fluid Ounce (FL OZ)

  • Cup

  • Pint (PT)

  • Quart (QT)

  • Ounce (Oz)

  • Pound (LB)

Apothecary System

• An older system of measurement in medicine.

• Key measurements include grain (gr) and various volumes.

Basic Math Review

• Fundamental Concepts:

  • Placement of whole numbers and decimals is crucial.

  • Understanding place values is key to accurately reading and writing numbers.

Fractions

• A way to represent parts of a whole:

  • Top Number (Numerator) / Bottom Number (Denominator)

  • Improper Fractions: Numerator > Denominator.

  • Mixed Fractions: Whole number + Fraction.

  • Conversion formula example:
    whole ext{ number} imes denominator + numerator / denominator

Percentages

• Represents a value as a part of 100. E.g. 75% = 75 / 100 = 0.75

• Calculation method: Convert percentage to decimal and multiply.

Ratios and Proportions

• Ratio: Relationship between two quantities.

  • Example: 1:20, 1/20, or 0.05.

• Proportion: Equation stating two ratios are equal.

  • Example: rac{1}{2} = rac{6}{12}

  • Allows solving for unknown quantities.

Dosage Calculations

• Importance: Essential for patient safety; miscalculations can lead to adverse health consequences.

• Basic math operations (addition, subtraction, multiplication, division) must be mastered.

Methods for Dosage Calculations

1. Basic Formula Method:
   rac{n}{a} imes v = dose

   • Where:

     • n = amount needed

     • a = amount available

     • v = vehicle (form)

2. Ratio and Proportion Method:

   • Set up equation:
     rac{Dosage ext{ on hand}}{Amount ext{ on hand}} = rac{Dosage ext{ desired}}{x ext{ (amount desired)}}

   • Follow steps: Convert, Construct, and Calculate.

Conversion Between Units of Measurement

• Important for ensuring correct dosage and administration.

• Use equivalent ratios to set up proportions.

• Example calculations:

  • 650 mg to grams: 1 g = 1000 mg. Set proportion: rac{1000 ext{ mg}}{1 ext{ g}} = rac{650 ext{ mg}}{x ext{ g}}

  • 12 ounces to ml: 8 oz = 240 ml. Set up proportion accordingly.

Weight-based Dose Calculations

• Required for medication prescribed according to patient's weight (kg).

• Conversion factor: 1 kg = 2.2 lbs.

Example:

1. Convert 24 lbs to kg.
   24 ext{ lbs} imes rac{1 ext{ kg}}{2.2 ext{ lbs}} = 10.9 ext{ kg}

2. Set up proportion for dosage based on weight.

Summary

• The metric system is predominant in healthcare; understanding it is vital.

• Familiarity with different measurement systems (household, apothecary) is required.

• Critical mathematical concepts include fractions, decimals, ratios, proportions, and percentages.

• Mastery of dosage calculations ensures patient safety through accurate medication administration.