Overview
This lecture explains how to use dimensional analysis for drug dosage calculations, focusing on converting between units using the metric table.
Introduction to Dimensional Analysis
- Dimensional analysis is a problem-solving technique used to convert between units in drug dosage calculations.
- It allows multiplication or division by ratios equal to one, changing units without altering the value.
- Learning the metric table is essential for efficient unit conversions.
Setting Up Dimensional Analysis Problems
- Problems are written with the given value and the unit to convert to (e.g., 8 g = ? mg).
- Set up a train of conversion factors ("diagonally") to cancel out undesired units.
- Focus on canceling units step-by-step until you reach the desired unit.
Example 1: Grams to Milligrams
- To convert 8 grams to milligrams, use the metric table: 1 g = 1,000 mg.
- Set up: 8 g × (1,000 mg / 1 g), grams cancel out.
- Multiply: 8 × 1,000 = 8,000 mg in 8 g.
Example 2: Grams to Micrograms
- To convert 8 grams to micrograms, use two steps: 1 g = 1,000 mg and 1 mg = 1,000 mcg.
- Set up: 8 g × (1,000 mg / 1 g) × (1,000 mcg / 1 mg), canceling grams and milligrams.
- Multiply: 8 × 1,000 × 1,000 = 8,000,000 mcg in 8 g.
Example 3: Milliliters to Ounces
- To convert 100 mL to ounces, use: 15 mL = 1 tbsp and 2 tbsp = 1 oz.
- Set up: 100 mL × (1 tbsp / 15 mL) × (1 oz / 2 tbsp), canceling mL and tbsp.
- Multiply and divide: (100 × 1 × 1) / (15 × 2) = 100 / 30 ≈ 3 oz.
Practice and Additional Resources
- Use practice quizzes and tutorials for more complex problems like IV boluses and weight-based dosages.
Key Terms & Definitions
- Dimensional Analysis — A method to convert between units by multiplying by conversion factors that equal one.
- Metric Table — A reference chart showing unit relationships (e.g., grams, milligrams, micrograms).
- Conversion Factor — A ratio equal to one, used to change from one unit to another without changing the value.
Action Items / Next Steps
- Memorize the metric table for faster problem-solving.
- Visit register nurse rn.com for printable metric tables, quizzes, and further video tutorials.
- Practice with more advanced conversion problems and quizzes available on the website.