Student Nurse Laura

Orem – "creative effort of one human being to help another human being."

IV Math

Posted by Laura on January 28, 2010

1. The doctor’s order is for an intravenous infusion of one liter of 5% Dextrose with Lactated Ringers (D5LR) to infuse at 125 ml/hr. How many hours will it take for the IV bag to infuse?

Since we are talking about infusion I would automatically start thinking what I am looking for is Hrs.

Hrs |

So I know my first conversion factor must have hrs as the numerator, and I like to start usually with what the doctor wants or what is on hand.


2. The physician’s new order is to infuse 1000 ml 5% Dextrose and 0.45 Normal Saline (D5 1/2 NS) with 40 mEq KCL, over 10 hours.  (a) what will the rate be using an infusion pump?  (b) How many milliliters will the patient receive in one day?

Here I think “rate” is always ml/hr. I’m also thinking infusion which is again Hrs. So I would start with Hrs or look for the mL/hr.  Remember from the answer above, infusions are total volume divided by mL/hr.


3. You are to infuse an antibiotic via IVPB. The order is for Cefazolin one-gram q 8 hrs. The medication book recommends the the infusion time of 30 minutes. The drug is supplied in 50 ml of NS. The tubing drip factor is 15 gtt/mL. (a) what will the drip rate be for the infusion?  (b) What will the rate be using an infusion pump?

Drip rate? Well, we know that means gtts/min right?


4. The order is for Erythromycin 750 mg in 250 mL of 5% D5W to infuse over 1.5 hours. The tubing drop factor is 15.  (a. ) what will the drip rate be for the infusion?  (b) What will the rate be using an infusion pump?

This one gets tricky. Drip rate again means gtts/min we are looking for, but you think where is the gtt conversion?  When it says factor, know it means per min or hr. If we are talking drops it will be per min, so use the 15gtts/min.


5. The physician’s order is to infuse a continuous IV of 1 liter or 1000 mL of NS with 20 mEq of KCL at 75 mL/Hr. (a) How many mL will the patient receive per day?  (b) If the infusion was started at 1:30 pm, at what exact time will the bag be totally infused?

This one is fun. I think the question (a) is a little off. You figure it will get infused before a full 24 hrs is complete. So then figure out how many hours it will take. For (b) I changed my hours to military or 2400 hrs, and added the total time. Make sure you have changed the part of an hour into minutes by multiplying the .33 of an hour by 60 to get you true minutes.


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