Overview
This lecture explains a six-step dimensional analysis method for solving nursing school dosage calculation problems, using a drops-per-minute IV infusion example.
Importance of the Six-Step Process
- Following the six-step process ensures accuracy on all dosage calculation problems.
- Memorizing formulas is discouraged since they may not work for complex or varied problems.
- Dimensional analysis (railroad method) is recommended as a universal approach for dosage calculations.
The Six Steps for Dosage Calculation
1. Identify the Desired Unit
- Read the question carefully to determine the final unit (e.g., drops per minute).
2. Write the Original Order
- Note the doctor's order with proper units (e.g., 1 liter over 8 hours).
3. Set Up Conversion Factors
- Identify and write down needed conversion factors found in the problem or by standard measurements (e.g., 20 drops/ml, 1000 ml/1 liter, 1 hr/60 min).
- Arrange conversion factors so unwanted units cancel out, leaving only the required units in the answer.
4. Multiply and Divide
- Multiply all numbers across the top and all numbers across the bottom of the setup.
- Divide the top product by the bottom product for the answer (e.g., 20,000 ÷ 480 = 41.6).
5. Apply Rounding Rules
- For drops per minute, round to the nearest whole number (never partial drops; e.g., 41.6 rounds to 42 drops per minute).
6. Double-Check Calculations
- Re-calculate to ensure accuracy, as correct dosages are critical for patient safety.
Key Terms & Definitions
- Dimensional Analysis/Railroad Method — A problem-solving process that uses unit cancellation to arrive at the correct answer.
- Conversion Factor — A ratio used to convert one unit into another (e.g., 1000 ml = 1 liter).
- Drops per Minute (gtts/min) — The number of IV drops delivered to a patient each minute.
Action Items / Next Steps
- Download the free dosage calculation cheat sheet.
- Practice additional problems using flashcards and workbooks.
- Double-check all answers for accuracy on exams.
- Review the full dose calculation course for further learning.