A nurse is preparing to administer dopamine 5 mcg/kg/min by continuous IV infusion to a client who weighs 220 lb. Available is 400 mg of dopamine in 250 mL of 0.9% sodium chloride. The nurse should set the IV pump to deliver how many mi/hr? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)
The Correct Answer and Explanation is:
To solve this problem, we need to calculate the rate at which the IV pump should deliver dopamine to the client. The steps are as follows:
Step 1: Convert the client’s weight from pounds to kilograms.
- Weight in pounds: 220 lb
- Conversion factor: 1 kg = 2.2 lb
Weight in kilograms=220 lb2.2 lb/kg=100 kg\text{Weight in kilograms} = \frac{220 \text{ lb}}{2.2 \text{ lb/kg}} = 100 \text{ kg}Weight in kilograms=2.2 lb/kg220 lb=100 kg
Step 2: Calculate the dosage in mcg/min.
The prescribed dosage is 5 mcg/kg/min.
Dosage=5 mcg/kg/min×100 kg=500 mcg/min\text{Dosage} = 5 \text{ mcg/kg/min} \times 100 \text{ kg} = 500 \text{ mcg/min}Dosage=5 mcg/kg/min×100 kg=500 mcg/min
Step 3: Convert mcg to mg.
Since the concentration is provided in mg and the dose is in mcg, we need to convert mcg to mg.
500 mcg/min=0.5 mg/min500 \text{ mcg/min} = 0.5 \text{ mg/min}500 mcg/min=0.5 mg/min
Step 4: Calculate the concentration of dopamine in the IV solution.
The available concentration is 400 mg in 250 mL of 0.9% sodium chloride.
Concentration=400 mg250 mL=1.6 mg/mL\text{Concentration} = \frac{400 \text{ mg}}{250 \text{ mL}} = 1.6 \text{ mg/mL}Concentration=250 mL400 mg=1.6 mg/mL
Step 5: Determine the infusion rate in mL/min.
Now, we calculate the infusion rate in mL/min.
Infusion rate=Dosage (mg/min)Concentration (mg/mL)\text{Infusion rate} = \frac{\text{Dosage (mg/min)}}{\text{Concentration (mg/mL)}}Infusion rate=Concentration (mg/mL)Dosage (mg/min)
Infusion rate=0.5 mg/min1.6 mg/mL=0.3125 mL/min\text{Infusion rate} = \frac{0.5 \text{ mg/min}}{1.6 \text{ mg/mL}} = 0.3125 \text{ mL/min}Infusion rate=1.6 mg/mL0.5 mg/min=0.3125 mL/min
Step 6: Convert the infusion rate from mL/min to mL/hr.
To set the IV pump, the rate needs to be in mL/hr.
Infusion rate (mL/hr)=0.3125 mL/min×60 min/hr=18.75 mL/hr\text{Infusion rate (mL/hr)} = 0.3125 \text{ mL/min} \times 60 \text{ min/hr} = 18.75 \text{ mL/hr}Infusion rate (mL/hr)=0.3125 mL/min×60 min/hr=18.75 mL/hr
Step 7: Round the answer to the nearest tenth.
The final infusion rate should be rounded to the nearest tenth.
Final answer=18.8 mL/hr\text{Final answer} = 18.8 \text{ mL/hr}Final answer=18.8 mL/hr
Explanation:
In clinical practice, accurate medication dosing is crucial to ensure patient safety and effective treatment outcomes. Dopamine is a potent vasopressor used to treat conditions such as shock and hypotension, so its dosage must be carefully calculated based on the patient’s weight to achieve the desired therapeutic effect without causing adverse effects.
The steps taken in this calculation are systematic and ensure that each conversion and calculation is precise. First, the patient’s weight was converted from pounds to kilograms because medication dosages in critical care are often weight-based. The dosage was then calculated in micrograms per minute, which was converted to milligrams to align with the available concentration of the medication. The infusion rate was derived based on this dosage and the concentration of dopamine in the IV solution. Finally, the rate was converted to mL/hr, the unit used by IV pumps, and rounded to ensure that the pump is set accurately.
Administering dopamine at the correct rate is vital to managing the patient’s condition effectively, making this calculation an essential skill for nurses in critical care settings.