A patient needs 30 mEq of Potassium Chloride added in 500 ml of Normal saline to be administered over 10 hours. The drug is available as 40 mEq in 20 ml ampoule. How will the nurse prepare the drug?

1. A

   30 ml potassium chloride / 500 ml normal saline

2. B

   12 ml potassium chloride / 500 ml normal saline

3. C

   14 ml potassium chloride / 500 ml normal saline

4. D

   15 ml potassium chloride / 500 ml normal saline

Appeared in: SCTIMST Staff Nurse - 2015 (Set-B)

Explanation

• The question requires calculating the volume of a liquid medication to be administered based on the prescribed dose and the available concentration.
• The standard formula for this calculation is (Desired Dose / Available Dose) × Available Volume.
• Plugging in the values from the question: The desired dose is 30 mEq, the available dose is 40 mEq, and the available volume is 20 ml.
• The calculation is (30 mEq / 40 mEq) × 20 ml, which equals 0.75 × 20 ml.
• The final result is 15 ml, which is the correct volume of Potassium Chloride to be drawn up.

Why Other Options Were Wrong

• Option A: This is incorrect. 30 ml is a miscalculation that might arise from confusing the desired dose in mEq with the required volume in ml.
• Option B: This is an incorrect calculation. It does not follow the standard drug calculation formula.
• Option C: This is an incorrect calculation. It does not follow the standard drug calculation formula.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Drug Dosage Calculation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Accurate drug calculation is a fundamental and critical nursing skill to ensure patient safety and prevent medication errors, especially with high-alert drugs like Potassium Chloride.
• Administering an incorrect dose of KCl can lead to life-threatening complications such as hyperkalemia, which can cause fatal cardiac dysrhythmias.
• What if the available drug was 20 mEq in 10 ml? The calculation would change to (30 mEq / 20 mEq) × 10 ml = 1.5 × 10 ml = 15 ml. The final volume is the same, but the nurse must use the correct values from the available vial to ensure accuracy.

How to Approach the Question

• First, identify the question type. This is an analytical, drug calculation question.
• Read the problem carefully to identify the three key pieces of information: the 'Desired' dose (what is ordered), the 'Have' or 'Available' dose (what is on hand), and the 'Volume' or 'Quantity' the available dose comes in.
• Write down the values: Desired = 30 mEq, Have = 40 mEq, Volume = 20 ml.
• Recall or write down the standard formula for liquid drug calculations: (Desired / Have) × Volume.
• Substitute the identified values into the formula: (30 / 40) × 20.
• Perform the calculation to find the correct volume to administer and compare your result with the given options.

Concept Tested & Keywords

• Concept Tested: Drug Dosage Calculation
• Stem keywords: Potassium Chloride, drug calculation, mEq, Normal saline
• Lead-in keywords: How will the nurse prepare

Question ID

QxkqjPJ4O2RJm9XSJjM60n

Copy ID

Reference Book

E6 Pharmacology Nurses Shanbhag 3e p. 54-56

E6 Pharmacology Nursing Lilley 11e Part 2 p. 170-172