Nitroglycerin 30 mcg/minute is prescribed for a client who is admitted with chest pain. Nitroglycerin 100 mg is dispensed in a solution of 250 mL of D5W. The nurse should program the infusion pump to deliver how many mL/hour? (Enter numerical value only. If rounding is required, round to the nearest tenth.)
The correct answer and Explanation is :
To determine the rate at which to set the infusion pump, follow these steps:
- Determine the concentration of the nitroglycerin solution: The total amount of nitroglycerin in the solution is 100 mg in 250 mL of D5W. Therefore, the concentration is:
[
\text{Concentration} = \frac{100 \text{ mg}}{250 \text{ mL}} = 0.4 \text{ mg/mL}
] - Convert the nitroglycerin dosage from mcg/min to mg/mL: The prescribed dosage is 30 mcg/min. First, convert mcg to mg:
[
30 \text{ mcg} = 0.03 \text{ mg}
] Thus, the dosage is 0.03 mg/min. - Calculate the volume of solution required per minute to deliver the prescribed dosage: Use the concentration to find out how many mL per minute are needed to deliver 0.03 mg/min:
[
\text{Volume (mL/min)} = \frac{\text{Dose (mg/min)}}{\text{Concentration (mg/mL)}} = \frac{0.03 \text{ mg/min}}{0.4 \text{ mg/mL}} = 0.075 \text{ mL/min}
] - Convert the volume from mL/min to mL/hour: There are 60 minutes in an hour, so multiply by 60:
[
\text{Volume (mL/hour)} = 0.075 \text{ mL/min} \times 60 \text{ min/hour} = 4.5 \text{ mL/hour}
]
So, the nurse should program the infusion pump to deliver 4.5 mL/hour.
Explanation
In this problem, calculating the correct infusion rate involves converting dosages and concentrations between different units and then determining the appropriate flow rate.
- Concentration Calculation: First, determine how concentrated the solution is, which is essential for understanding how much of the medication is in each mL of the infusion. This concentration tells you how many milligrams of nitroglycerin are present in each milliliter of the solution.
- Dosage Conversion: Next, convert the dosage from micrograms to milligrams because the concentration is given in mg/mL. This step ensures that both the dose and concentration are in compatible units.
- Volume Calculation: Using the concentration, find out how much volume per minute is needed to administer the prescribed dosage. This is a direct application of the formula (\text{Volume (mL/min)} = \frac{\text{Dose (mg/min)}}{\text{Concentration (mg/mL)}}).
- Rate Conversion: Finally, convert the per-minute infusion rate to a per-hour rate to set the infusion pump correctly.
By following these steps, you ensure that the medication is delivered accurately, which is crucial for patient safety and effectiveness of treatment.