A child is to receive dexamethasone (Decadron) intravenously at the ordered dosage of 7.6 mg. The drug concentration in the vial is 4 mg/mL. Which of the following amount would the nurse administer?

1. A

   0.05 mL

2. B

   0.72 mL

3. C

   1.9 mL

4. D

   3.8 mL

Appeared in: OSSSC Nursing Officer-2021

Explanation

• The question requires the calculation of a medication volume based on a prescribed dose and the available drug concentration.
• The standard formula for this calculation is: (Desired Dose / Available Dose) × Quantity = Amount to Administer.
• Plugging in the given values: The desired dose is 7.6 mg, and the available concentration is 4 mg in 1 mL.
• The calculation is (7.6 mg / 4 mg) × 1 mL, which equals 1.9 mL.

Why Other Options Were Wrong

• Option A: This value is significantly lower than the correct dose and likely results from a gross miscalculation, possibly by inverting the numbers and making additional errors.
• Option B: This value is incorrect and may result from a calculation error, such as a slip in division or multiplication.
• Option D: This value is exactly double the correct amount. This error could occur if the nurse incorrectly divides 7.6 by 2 instead of 4, perhaps by misreading the concentration or making a simple mental math error.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Drug Dosage Calculation to guide bedside assessment, documentation, and the next nursing action.
• Accurate drug calculation is a fundamental and critical nursing skill. Errors can lead to underdosing (ineffective treatment) or overdosing (toxicity and harm), making this a major patient safety issue.
• This skill is a core component of the 'Six Rights of Medication Administration,' specifically the 'Right Dose.' Always double-check calculations, especially for high-alert medications and pediatric patients.
• What if the drug concentration was 8 mg/mL instead of 4 mg/mL? The calculation would be (7.6 mg / 8 mg/mL) = 0.95 mL. This demonstrates how crucial it is to carefully read the vial's concentration before every administration.

How to Approach the Question

• First, identify the question as a dosage calculation problem.
• Next, extract the key values from the problem: the desired dose (7.6 mg) and the available concentration (4 mg/mL).
• Recall the standard formula for drug calculations: (Desired Dose / Available Dose) × Volume.
• Substitute the values into the formula: (7.6 / 4) × 1.
• Perform the mathematical calculation to find the correct volume.
• Compare your calculated answer with the given options to select the correct one.

Concept Tested & Keywords

• Concept Tested: Drug Dosage Calculation
• Stem keywords: dexamethasone, intravenously, ordered dosage, 7.6 mg, drug concentration, 4 mg/mL
• Lead-in keywords: Which of the following amount
• Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.

Question ID

Qh1Wk_CjRsXG6mNBgAsGDB

Copy ID

Reference Book

E6 Nursing Fundamentals Potter Perry 12e Part 3 pp. 142-144, 143-145