Bonus free practice exam #2 question #10 setup

by Jonn
(Willoughby, Ohio )

Can you show how to get the answer to this one?



Reply (Keith): Sure, Here it is:
An IV Drip is ordered to run at 4 gtt/min. It contains 875 mg of a drug in a 250 ml solution. How many mg will the patient receive per hour if the infusion set is calibrated to deliver 12 gtt/ml?

a. 0.70mg/hr

b. 16mg/hr

c. 70mg/hr

d. 160mg/hr

So,


1. How many mL per Min.?
12 gtt/mL means that it takes 12 drops to equal 1mL.
4 gtt/min is how many drops will fall every min.
12 Divided by 4 = 3
So that's = 1mL every 3 minutes
(right?, since also 4 times 3 equals 12)



2. How much drug per mL?
875mg drug divided by 250mL = 3.5mg/mL



3. How many mL per Hr.
and 60 minutes (one hour) divided by 3 = 20

since one mL will drop 20 times per hour
(or every 3 minutes)


4. Add it all up.
Then 20 X 3.5mg/mL = 70mg/hr

This infusion device math is kind of confusing at first. Sometimes drawing a circle (representing a minute) and then drawing little drops in it helps to visualize it. I know that sounds a little silly, but it works for lots of people.