Dobutamine 500 mg in 250 mL D5W at 5 mcg/kg/min via IV pump. Patient weighs 152 lbs. How many mL/hour should the patient receive?
The correct answer and explanation is :
To calculate how many mL/hour the patient should receive, we need to work through the steps carefully. Here’s how to approach this:
Step 1: Convert the patient’s weight from pounds to kilograms.
The patient weighs 152 lbs. To convert pounds to kilograms, we use the conversion factor:
[
1 \, \text{lb} = 0.4536 \, \text{kg}
]
So, the patient’s weight in kilograms is:
[
152 \, \text{lbs} \times 0.4536 = 68.95 \, \text{kg}
]
Step 2: Calculate the required dose in mcg/min.
The order specifies that the patient should receive 5 mcg/kg/min. To calculate the dose in mcg/min, we multiply the patient’s weight in kilograms by the dose rate:
[
68.95 \, \text{kg} \times 5 \, \text{mcg/kg/min} = 344.75 \, \text{mcg/min}
]
Thus, the patient needs to receive 344.75 mcg/min.
Step 3: Determine how many mcg are in 1 mL of the solution.
The concentration of the solution is 500 mg of dobutamine in 250 mL of D5W. First, convert 500 mg to mcg (since 1 mg = 1000 mcg):
[
500 \, \text{mg} \times 1000 = 500,000 \, \text{mcg}
]
Now, divide the total number of mcg by the volume of the solution to find the concentration in mcg/mL:
[
\frac{500,000 \, \text{mcg}}{250 \, \text{mL}} = 2000 \, \text{mcg/mL}
]
Thus, the concentration is 2000 mcg/mL.
Step 4: Calculate the required mL/hour.
We know the patient needs 344.75 mcg/min. To determine how many mL of the solution should be administered to deliver that dose, we use the concentration (2000 mcg/mL):
[
\frac{344.75 \, \text{mcg/min}}{2000 \, \text{mcg/mL}} = 0.172375 \, \text{mL/min}
]
Now, convert this rate to mL/hour:
[
0.172375 \, \text{mL/min} \times 60 \, \text{min/hour} = 10.34 \, \text{mL/hour}
]
Thus, the patient should receive 10.34 mL/hour.
Final Answer:
The correct infusion rate is 10.34 mL/hour.
This calculation ensures that the patient receives the correct dosage based on their weight, the medication concentration, and the desired rate of infusion.