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Difficulty: HardPharmacological and Parenteral Therapies

A nurse is caring for a client in the intensive care unit who is experiencing a hypertensive emergency. The client weighs 209 lbs209\text{ lbs}. The healthcare provider prescribes a continuous intravenous infusion of sodium nitroprusside at 3 mcg/kg/min3\text{ mcg/kg/min}. The pharmacy dispenses a premixed IV bag containing 50 mg50\text{ mg} of sodium nitroprusside in 250 mL250\text{ mL} of 5%5\% dextrose in water (D5W).

At what rate, in mL/hr\text{mL/hr}, should the nurse set the infusion pump? (Record your answer using one decimal place.)

Answer: 85.5 mL/hr

Answer

85.5
To safely administer a weight-based continuous IV infusion ordered in mcg/kg/min, the nurse must execute several sequential conversions. First, convert the weight to kg (209 lbs / 2.2 = 95 kg). Next, find the hourly dose by multiplying the weight by the order and then by 60 minutes (95 kg * 3 mcg/kg/min * 60 min/hr = 17,100 mcg/hr). Then, determine the concentration of the IV bag by converting mg to mcg (50 mg = 50,000 mcg) and dividing by the volume (50,000 mcg / 250 mL = 200 mcg/mL). Finally, divide the required hourly dose by the concentration to find the correct pump rate (17,100 mcg/hr / 200 mcg/mL = 85.5 mL/hr).

Step-by-Step Solution

1
Convert the client's weight to kilograms.
95 kg
The medication is dosed based on weight in kg, but the client's weight is provided in lbs.
2
Calculate the patient-specific dose per minute.
285 mcg/min
Multiply the prescribed dose (3 mcg/kg/min) by the client's weight in kg to find the total per-minute dose.
3
Calculate the dose per hour.
17,100 mcg/hr
Infusion pumps are programmed in mL/hr, so the dose must reflect an hourly rate rather than a minute rate.
4
Convert the medication weight in the bag from mg to mcg.
50,000 mcg
The prescribed dose is calculated in mcg, but the IV bag contains mg. Units must match to calculate concentration.
5
Calculate the IV bag concentration.
200 mcg/mL
Divide the total micrograms (50,000) by the total volume (250 mL) to determine how many micrograms are in each mL.
6
Calculate the infusion pump rate in mL/hr.
85.5 mL/hr
Divide the required hourly dose (17,100 mcg/hr) by the concentration (200 mcg/mL) to find the volume needed per hour.

Key Concept

Weight-based critical care continuous intravenous infusion calculations requiring multiple unit conversions
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Topics

Pharmacological and Parenteral Therapies

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