Question

1. Available: 10 mg Nitroglycerine in 250 ml D5W

Patient weighs 85 kg. Infusion rate is 2.5 ml/hr

How many mcg/min is the patient receiving? Round to the nearest 10^th.

2. Order: 10 mcg/kg/min Dobutamine

Patient weighs 175 lb

Available: Dobutamine HCl 500 mg/250 ml D5W

At what rate will the nurse set the IV infusion pump? (ml/hr) Round to nearest whole number.

How long will it take before the total available volume is completely administered?

Answer 1

1.Given here is 10 mg Nitroglycerine in 250 ml D5W which means 0.04mg Nitroglycerine in 1 ml D5W.

Since 1mg=1000 mcg

0.04mg/ml= 0.04×1000=40mcg/ml.

Infusion rate given is 2.5 ml/hr
So in 60 minutes 2.5 ml.will be infused.

In 1 ml 40mcg is present so in 2.5 ml 2.5×40= 100mcg will be present.

So in 60 minutes 100 mcg will be infused.

Here it is asked to calculate the rate in mcg/min.

So in 1 minute 100÷60= 1.666 mcg will be infused.

Rounding off the value we get 1.67mcg/min

So the answer is 1.67mcg/min.

2. Given Order is 10 mcg/kg/min Dobutamine

Patient weighs 175 lbs
Since 2.2lbs=1 kg
So 175lbs=79.5 kg

Availability is Dobutamine HCl 500 mg/250 ml D5W
Which means 2mg Dobutamine in 1ml which means 2000 mcg in 1ml since 1mg=1000mcg.

We have to calculate the infusion rate in ml/hour.

So to calculate the infusion rate se can use a very simple formula:-

Infusion rate(ml/hr)={ Patient's weight(kg)×Dose(mcg/kg/min)×60}÷Available concentration of the Drug

Putting values in the formula:-

Infusion rate=(79.5×10×60)÷2000=23.85ml/hr=24ml/hr

Total available volume is 250ml.
In 1 hr 24 ml is being administered so 250ml would be administered in 250÷24=10.41hr=10hrs

So in 10 hrs total available volume would be administered.