A patient is prescribed dopamine at 15 mcg/min. The prepared infusion is dopamine 5 mg in 500 mL D5W. What IV pump rate (mL/hr) should be set to deliver the ordered dose?

1. A

   9 mL/hr

2. B

   19 mL/hr

3. C

   90 mL/hr

4. D

   180 mL/hr

Appeared in: NORCET 9 Prelims-2025

Explanation

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• The calculation correctly determines the IV pump rate required to deliver a prescribed dose of medication over time.
• First, the total drug amount is converted to micrograms (5 mg = 5000 mcg).
• Then, the concentration of the solution is calculated (5000 mcg / 500 mL = 10 mcg/mL).
• The required rate in mL/min is found by dividing the prescribed dose by the concentration (15 mcg/min / 10 mcg/mL = 1.5 mL/min).
• Finally, this rate is converted to mL/hr by multiplying by 60 (1.5 mL/min * 60 min/hr = 90 mL/hr).

Why Other Options Were Wrong

• Option A: This rate is ten times lower than the correct rate. It likely results from a decimal point error during the final conversion step (e.g., multiplying 1.5 by 6 instead of 60, or incorrectly dividing 90 by 10).
• Option B: This value does not correspond to any logical step or common error in the dosage calculation formula. It is an arbitrary incorrect value.
• Option D: This rate is double the correct rate. This error could occur if the rate in mL/min (1.5) was incorrectly multiplied by 120, or if the concentration was mistakenly calculated as half its actual value (5 mcg/mL).

Related Visual

• Visual 1: Flowchart: Step-by-step process for IV dosage calculation, starting from converting units to the final mL/hr rate.
• Visual 2: Formula Graphic: A visual representation of the dosage calculation formula: Rate (mL/hr) = [Prescribed Dose (mcg/min) / Concentration (mcg/mL)] x 60 min/hr.

Clinical Relevance

• Nursing practice connection: Use the key finding related to IV Infusion Rate Calculation to guide bedside assessment, documentation, and the next nursing action.
• Accurate dosage calculation is a critical nursing skill to ensure patient safety and therapeutic effectiveness, especially with potent medications like dopamine.
• Vasoactive drugs like dopamine require precise titration using an infusion pump because small variations in dose can cause significant, rapid changes in blood pressure and heart rate.
• What if the infusion bag was 250 mL instead of 500 mL? The concentration would double (5000 mcg / 250 mL = 20 mcg/mL). The final rate would be halved to 45 mL/hr to deliver the same 15 mcg/min dose.

How to Approach the Question

• Identify the goal: The question asks for the IV pump rate in mL/hr.
• List the known values: Prescribed dose (15 mcg/min), available drug (5 mg), and total volume (500 mL).
• Recognize the need for unit conversion: The dose is in mcg/min, but the available drug is in mg and the final rate is in mL/hr. Plan your conversions.
• Calculate the concentration of the drug in the IV bag (mcg/mL).
• Use the formula: Rate (mL/hr) = (Dose Ordered / Concentration) x 60. Plug in your values.
• Double-check your math, paying close attention to decimal points and conversion factors.

Concept Tested & Keywords

• Concept Tested: IV Infusion Rate Calculation
• Stem keywords: dopamine, mcg/min, mg in mL, IV pump rate, mL/hr
• Lead-in keywords: What
• Negative lead-in flag: false

Question ID

QPX561jBK_lROnQeOmmz7C

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