Question

Dopamine is available as 400 mg in 250 mL of D5W. A 2 year old weighing 12 kg is receiving 10 mcg/kg/min. How many hours will the infusion last?

Answer 1

55.5556 hours.

Explanation:

Let's solve the problem.

The amount of dopamine rate applied to a person is based on the formula: 10mcg/kg/min. Such relation can be express as follows:

(10mcg/kg/min)=

(10mcg/kg)*(1/min)

Now by multiplying by the weight (12 kg) of the 2 years old person, we have:

(10mcg/kg)*(1/min)*(12kg)=

(10mcg*12kg/kg)*(1/min)=

(120mcg)*(1/min)=

120mcg/min, which is the rate of dopamine infusion, which can be express as:

(120mcg/min)*(60min/1hour)=

(120mcg*60min)/(1hour*1min)=

7200mcg/hour=

1hour/7200mcg, which means that for each hour, 7200mcg dopamine are infused.

Because the D5W product has 400 mg of dopamine, then we need to convert 400 mg to X mcg of dopamine in order to use the previous obtained rate. This means:

Because 1mcg=0.001mg then:

(400mg)*(1mcg/0.001mg)=

(400mg*1mcg)/(0.001mg)=

400000mcg, which is the amount of dopamine in D5W.

Now, using the amount of dopamine in D5W and the applied rate we have:

(rate)*(total amount of dopamine)=hours of infusion

(1hour/7200mcg)*(400000mcg)=hours of infusion

(1hour*400000mcg)/(7200mcg)=hours of infusion

(55.5556 hours) =hours of infusion

In conclusion, the infusion will last 55.5556 hours.