A doctor has prescribed 2 liters of Normal Saline to be infused at a rate of 250 ml per hour. How long will the infusion take to complete?

1. A

   1 hour

2. B

   7 hours

3. C

   8 hours

4. D

   10 hours

Appeared in: KGMU 2023

Explanation

• The core of this question is a dosage calculation problem, specifically determining the total time for an IV infusion.
• The formula for infusion time is: Total Volume ÷ Infusion Rate per Hour.
• First, all units must be consistent. The total volume of 2 liters must be converted to milliliters (mL) to match the rate's unit (mL/hr).
• Since 1 L = 1000 mL, 2 L is equal to 2000 mL.
• Finally, dividing the total volume (2000 mL) by the hourly rate (250 mL/hr) gives the total infusion time: 2000 / 250 = 8 hours.

Why Other Options Were Wrong

• Option A: This is incorrect. Infusing 2000 mL in 1 hour would require a rate of 2000 mL/hr, which is eight times faster than the prescribed rate of 250 mL/hr.
• Option B: This is incorrect. An infusion time of 7 hours would imply an infusion rate of approximately 286 mL/hr (2000 mL / 7 hr), which is faster than the prescribed rate.
• Option D: This is incorrect. An infusion time of 10 hours would imply an infusion rate of 200 mL/hr (2000 mL / 10 hr), which is slower than the prescribed rate.

Related Visual

• Visual 1: Infographic: A simple visual showing the formula: Total Volume (mL) / Rate (mL/hr) = Time (hr).
• Visual 2: Diagram: An image of an IV bag and an infusion pump with the rate set to '250 mL/hr' to help visualize the clinical context.

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain IV infusion time calculation as background academic context rather than a clinical decision trigger.
• Accurate calculation of IV infusion times is a critical nursing skill to ensure patient safety and therapeutic effectiveness. Incorrect calculations can lead to fluid overload or delayed treatment.
• Nurses must double-check all calculations, especially for high-risk medications or fluids. Using a calculator and having a second nurse verify the calculation is a common safety protocol.
• What if the infusion pump malfunctions and the rate increases to 500 mL/hr? The nurse must immediately recognize that the infusion will finish in 4 hours instead of 8, increasing the risk of fluid overload. The nurse's primary action would be to stop the infusion, assess the patient for signs of fluid overload (e.g., respiratory distress, edema), correct the rate, and notify the provider.

How to Approach the Question

• Identify the goal of the question: to find the total infusion time.
• Extract the key numerical values from the stem: Total Volume = 2 liters, Infusion Rate = 250 mL/hr.
• Check for unit consistency. The volume is in liters and the rate is in mL/hr. Convert the volume to mL: 2 L * 1000 mL/L = 2000 mL.
• Apply the correct formula for infusion time: Time = Total Volume / Rate.
• Perform the calculation: 2000 mL / 250 mL/hr = 8 hours.
• Select the option that matches your calculated result.

Concept Tested & Keywords

• Concept Tested: IV infusion time calculation
• Stem keywords: Normal Saline, infusion rate, 250 ml per hour, 2 liters
• Lead-in keywords: How long

Question ID

Q0lT7IhvDU1_LBZxeP3gGs

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