question about iv calculations

On the bonus quiz #2 question #10. Can you explain how to do that.


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

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Reply (by Keith)


The way I would do it is to first write down the factors.

Then I want to know how many drips will drop in one hour.

4gtt/min X 60 Min. = 240 gtt/hour

Next, I want to know how many ml that is.

Since each 12 gtt's adds up to 1 ml, I divide my total gtt / per hour by how many equal one 1 ml.

240 gtt/hr ÷ 12 gtt / ml = 20

That means that 20ml will drop each hour


Now, I want to know how many mg of the drug is in 20 ml.


So, take the known concentration and bounce 20 ml off of that to find out your answer. (proportion math)


875mg                  X
  ------        =      -----

250ml             20ml