IV drip calculations

I can't remember the formulas for determining the doseage such as mcg/min and mcg/kg/min when only ml/hr infusing , kg wt and concentration known. I had a reference sheet for IV drip calculations but I lost it. I can remember how to calculate IV drip rates but I must be getting old because I can't recall how to determine doseage infusing from ml/hr infusing on pump. Anyone willing to share formulation, I'd be so grateful. Thanks.


May 22, '08When I was in school they gave us an ACCN sheet with all three formulas on it it was awsome it was one of there "drug cards" I kept it taped to my clipboard I will try to find it but it was the best one I have seen  might be able to find it on there site

May 22, '08This is a simple formula that uses linear algebra and a little fraction/cross multiplication action. I use this one quite often. Then, I double check with a flow rate calculator on my PDA. lol
So let's say you are going to hand a dopamine infusion. You have 400 mg in 250 ml of solution. You want to start your infusion at 10 mcg/kg/min. The patient is 70 kg.
First, I want to know how many mg an hour I will need to give this patient. I take 10 and multiply by 70. This gives me mcg per minute.
This should be 700 mcg.
Next, I want to know how many mcg an hour I will be giving. So, I take 700 and multiply by 60. (60 minutes in an hour) This should equal 42,000 mcg.
Now, I want to convert the mcg to mg so I am working with the same units of measure throughout my formula. Remember, 1000 mcg equals 1 mg. So, we simply divide 42,000 by 1000. This should give us 42 mg per hour.
Now we have all of the information we need to set up our formula.
On the left side, I set up what I have on hand. 400mg
_____
250ml
On the right side I set up what I need to give. 42mg
____
X
The X will be ML/hr.
The completed formula should look like this:
400mg 42mg
___________________
250 ML X ML
Now, we cross multiply and solve X.
Cross multiply first, and we have: 400X = 250 multiplied by 42.
The result should be: 400X = 10, 500
Now we simply treat this like linear algebra and divide both sides by 400 and isolate X.
400X divided by 400 = X and 10, 500 divided by 400 = 26.25
So, X= 26.25 ML/hr. Most will round down to 26 Ml/Hr. 