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Difficulty: MediumPharmacological and Parenteral Therapies

A patient admitted with a hypertensive emergency requires a continuous intravenous infusion of nitroglycerin. The provider orders a rate of 25 \mug/min25 \text{ \mu g/min}. The pharmacy delivers a standard premixed glass bottle containing 50 mg50 \text{ mg} of nitroglycerin in 250 mL250 \text{ mL} of 0.9% sodium chloride0.9\% \text{ sodium chloride}.

Calculate the correct electronic infusion pump setting in mL/hr\text{mL/hr}. (Record your answer rounding to the nearest tenth.)

Answer: 7.5 mL/hr

Answer

The infusion pump should be set to deliver 7.5 mL/hr7.5 \text{ mL/hr}.
To find the correct infusion rate, the nurse must ensure all units of measurement align. First, convert the prescribed per-minute dose to an hourly rate: 25 \mug/min×60 min/hr=1500 \mug/hr25 \text{ \mu g/min} \times 60 \text{ min/hr} = 1500 \text{ \mu g/hr}. Next, determine the concentration of the available IV bag. Convert the 50 mg50 \text{ mg} of nitroglycerin to micrograms (50 mg×1000=50,000 \mug50 \text{ mg} \times 1000 = 50,000 \text{ \mu g}) and divide by the total volume of 250 mL250 \text{ mL}, which equals 200 \mug/mL200 \text{ \mu g/mL}. Finally, divide the required hourly dose by the concentration: 1500 \mug/hr÷200 \mug/mL=7.5 mL/hr1500 \text{ \mu g/hr} \div 200 \text{ \mu g/mL} = 7.5 \text{ mL/hr}.

Step-by-Step Solution

1
Calculate the total dose required per hour.
1500 \mug/hr1500 \text{ \mu g/hr}
The prescribed rate is per minute, but the infusion pump requires an hourly rate.
2
Convert the total amount of medication in the IV bottle to micrograms.
50,000 \mug50,000 \text{ \mu g}
To ensure units match the prescribed dose before determining the concentration.
3
Determine the concentration of the medication in the IV fluid.
200 \mug/mL200 \text{ \mu g/mL}
This establishes how much medication is contained in each milliliter of the solution.
4
Calculate the final infusion rate in mL/hr.
7.5 mL/hr7.5 \text{ mL/hr}
Dividing the hourly dose by the concentration yields the volume required per hour.

Key Concept

Intravenous medication dosage calculation requiring unit conversions
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Topics

Pharmacological and Parenteral Therapies

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