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IV flow rate calculation question

by gina
(texas)

Rx Claforan 500mg/50ml IV 50mg/kg/dose the patient weighs 22lb. how many minute will take to administer the IV if the administration set is calibrated at 20gtt./ml and flow rate is set at 30 gtt./min?

Comments for IV flow rate calculation question

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Dimensional analysis
by: Anonymous

One dose:
22 lb X (1 kg/2.2 lb) X (50 mg/kg)
= 500 mg

Time to infuse one dose:
500 mg X (50 mL/500 mg) X (20 gtt/mL) X (1 min/30 gtt)
= 33 1/3 minutes
lost
by: Anonymous

Our pharmacy doesn't supply/formulate IV mixtures. Having difficulties figuring out how?
help
by: Anonymous

This calculation seems confusing
Can you please make it easier?
Thanks!
another easy way, hope it helps
by: Anonymous

pt weight 22lb
50mg/kg/dose
we can do this
50mg* 1kg * 22lb * 50ml* 20gtt.* 1min 33.3min
kg 2.2lb 500mg ml 30gtt
Calculation
by: falantina

1kg= 2,2Ib
x = 22Ib
1kg*22Ib
--------- =10kg
2,2Ib
10kg*50mg 5oomg

500mg-- 50ml
500mg--- x ml


500mg*50ml
--------- = 50ml
50
50ml*20gtt \mint
------------------ -=33,3
30ggt
I hope this helps
by: Tiffany Brooks

First, you need to convert the Patients weight to Kg.(1Lb=2.2Kg) 22Lbs/2.2Kg=10Kg......Now that you have converted their weight you plug it in to the formula....50mg/kg/dose = 500mg/10kg/dose, which means for every Kg there is 50mg, so you multiply...50mg*10kg=500mg......Dose=500mg

Second, you know it is 20gtt/1ml and 30gtt/min..

So, for every 20 drops your getting 1ml, and you know the drug written for is 500mg/50ml. Now you multiply 50ml*20gtt= 1000gtt total to get the dose prescribed.

Third.... Now you need to find out how long the patient needs the IV ran for. You know its 30gtt/min..... All you need to do is divide the total drops by the 30gtt/min....

1000gtt/30gtt= 33.33 min

Your answer is.... 33.33 min
Beyond Helpful
by: jaybug2007

Wonderful explanation (to the second person). I was able use this information to refresh and rejuvenate my memory so that I could explain to help another fellow technician pass the technician certification exam conducted by our employer.

Thanks to the website founders for inventing this site for us techs!!!
Dimensional analysis method
by: Brad Wojcik, Pharm D

I think the easiest way and most entertaining way is to use dimensional analysis. You can set the whole problem up in one step, make sure everything is correct, then do the calculations. In this case you are starting with 22 lb and have to end up with min/dose. You can start by writing those down. 22 lb = min/dose, then start adding the ratios so that you end up with min/dose.
22 lb(1kg/2.2lb)(50mg/kg*dose)(50ml/500mg)(20gtt/mL)(1 min/30gtt)= 33.3 min. Note that 50mg/kg/dose can also be written 50mg/kg*dose, which is easier to use.

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