In a 28 year old patient Adrenaline to be infused at the rate of 0.2 mcg/kg/minutes. The weight of the patient is 40 kg. The medicine available in ampoule is 4 mg (2 mg/ml) and 2 ampoules to be added in 46 ml Normal saline. How many ml per minute dose would be administered?

1. A

   1 ml

2. B

   2 ml

3. C

   3 ml

4. D

   None of the above

Appeared in: NORCET -4 , 2023

Explanation

Listen in Hindi

• The calculation requires finding the required dose in mcg/min, the total drug concentration in the prepared solution, and then dividing the required dose by the concentration.
• The patient requires 8 mcg/min of Adrenaline (0.2 mcg/kg/min * 40 kg).
• The prepared solution has a total of 8000 mcg of Adrenaline in 50 ml of fluid, resulting in a concentration of 160 mcg/ml.
• Dividing the required dose by the concentration (8 mcg/min / 160 mcg/ml) yields an infusion rate of 0.05 ml/min.
• Since 0.05 ml/min is not one of the numerical options provided, 'None of the above' is the correct choice.

Why Other Options Were Wrong

• Option A: An infusion rate of 1 ml/min would deliver 160 mcg/min (1 ml/min * 160 mcg/ml), which is 20 times the required dose of 8 mcg/min. This is a significant overdose.
• Option B: An infusion rate of 2 ml/min would deliver 320 mcg/min (2 ml/min * 160 mcg/ml), which is 40 times the required dose. This is a life-threatening overdose.
• Option C: An infusion rate of 3 ml/min would deliver 480 mcg/min (3 ml/min * 160 mcg/ml), which is 60 times the required dose. This is an extreme overdose. This value corresponds to the rate in ml/hour, not ml/minute.

Related Visual

• Visual 1: Flowchart: Step-by-step process for calculating IV infusion rates, starting from desired dose (mcg/kg/min) and ending with final rate (ml/min or ml/hr).
• Visual 2: Infographic: A visual guide showing the 'Desired Dose, Have on Hand, and Vehicle' method for drug calculations, applying it to this specific problem.

Clinical Relevance

• Nursing practice connection: Use the key finding related to Drug Dose Calculation for Continuous IV Infusion to guide bedside assessment, documentation, and the next nursing action.
• Accurate dose calculation is a critical nursing skill to prevent medication errors, especially with potent drugs like Adrenaline where small errors can have severe consequences on blood pressure and heart rate.
• Nurses must always double-check their calculations, especially for high-alert medications. Using a systematic, step-by-step approach reduces the risk of errors.
• What if the infusion pump could only be set to the nearest whole ml/hr? The calculated rate is 3 ml/hr. If the pump only allowed increments of 1 ml/hr, setting it to 3 ml/hr would be the correct action. However, if the pump allowed for decimal places (e.g., 3.0 ml/hr), that would be even more precise.

How to Approach the Question

• Identify all the given values: prescribed dose rate, patient weight, drug availability (total mg and concentration), and diluent volume.
• Follow a systematic, step-by-step process. First, calculate the total required dose for the patient in mcg/minute.
• Next, calculate the total amount of drug and the total volume of the final solution to determine its concentration (mcg/ml).
• Finally, use the formula: Infusion Rate (ml/min) = Required Dose (mcg/min) / Concentration (mcg/ml).
• Carefully check the units at each step to ensure they cancel out correctly.
• Compare your final calculated answer to the given options. If it doesn't match any of the numerical options, consider if 'None of the above' is the correct choice.

Concept Tested & Keywords

• Concept Tested: Drug Dose Calculation for Continuous IV Infusion
• Stem keywords: Adrenaline, infusion rate, 0.2 mcg/kg/minutes, 40 kg, 4 mg ampoule, 46 ml Normal saline
• Lead-in keywords: How many

Question ID

Q-czJ3eLLXf764v5mBrI02

Copy ID