A patient (weight: 60 kg) admitted to critical care unit is to be administered with inj. methyl prednisolone 5.4 mg/kg/hour. The nurse dilutes 2 g methyl prednisolone in 50 ml of normal saline. Calculate the rate of infusion.

1. A

   8.1 ml/hour

2. B

   7.5 ml/hour

3. C

   9.4 ml/hour

4. D

   9 ml/hour

Appeared in: GMCH Nursing Officer-2025

Explanation

• The calculation requires a three-step process to determine the final infusion rate in ml/hour.
• First, calculate the total required dose per hour by multiplying the patient's weight (60 kg) by the prescribed dose (5.4 mg/kg/hour), which equals 324 mg/hour.
• Second, determine the concentration of the prepared solution by dividing the total amount of drug in milligrams (2 g = 2000 mg) by the total volume of the diluent (50 ml), which yields 40 mg/ml.
• Finally, divide the required hourly dose (324 mg/hour) by the drug concentration (40 mg/ml) to find the infusion rate, which is 8.1 ml/hour.

Why Other Options Were Wrong

• Option B: This value is incorrect and likely results from a miscalculation, possibly by using an incorrect patient weight or an error in dividing the dose by the concentration.
• Option C: This value is incorrect. This error could arise from miscalculating the initial total hourly dose or the concentration of the solution.
• Option D: This value is incorrect. It may be the result of rounding errors or a mistake in one of the calculation steps, such as the conversion from grams to milligrams.

Related Visual

• Visual 1: Infographic - A clear visual breakdown of the infusion rate calculation formula: Rate (ml/hr) = [Dose Required (mg/hr) / Concentration Available (mg/ml)]. Each component of the formula would be explained with the values from the question.
• Visual 2: Flowchart - A step-by-step flowchart showing the process: 1. Calculate Total Hourly Dose -> 2. Calculate Drug Concentration -> 3. Calculate Infusion Rate.

Clinical Relevance

• Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing Intravenous drug dosage and infusion rate calculation in acute care settings.
• Accurate drug calculation is a fundamental and critical nursing skill that directly impacts patient safety. Errors in calculation can lead to underdosing (ineffective treatment) or overdosing (toxicity), both of which can have severe consequences, especially in critical care.
• Methylprednisolone is a high-alert medication. Nurses must adhere to the 'five rights' of medication administration and use safety protocols like independent double-checks for all dosage calculations.
• What if the nurse diluted the 2 g of methylprednisolone in 100 ml of normal saline instead of 50 ml? The concentration would be halved (2000 mg / 100 ml = 20 mg/ml). To deliver the same 324 mg/hour, the infusion rate would need to be doubled to 16.2 ml/hour (324 mg/hr / 20 mg/ml). This demonstrates how the dilution volume is a critical variable in the calculation.

How to Approach the Question

• First, identify all the given information in the problem: patient weight (60 kg), prescribed dose (5.4 mg/kg/hour), total drug amount (2 g), and total solution volume (50 ml).
• Next, determine the final unit required for the answer, which is 'ml/hour'. This is your target.
• Break the problem into smaller steps. First, calculate the total dose needed for the patient in mg/hour.
• Then, calculate the concentration of the drug you have on hand in mg/ml. Remember to convert grams to milligrams.
• Finally, use the desired dose and the available concentration to calculate the infusion rate in ml/hour.
• Always double-check your calculations to prevent medication errors.

Concept Tested & Keywords

• Concept Tested: Intravenous drug dosage and infusion rate calculation.
• Stem keywords: methyl prednisolone, rate of infusion, drug calculation, 60 kg, 5.4 mg/kg/hour
• Lead-in keywords: Calculate
• Negative lead-in flag: false

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