Drug Calculations/IV GTT Rates for EMT Advanced

[Akulahawk]

There are only 2 simple steps to calculate a drug given by IVP:

• First, figure out how much drug you need to administer. This is simply the known dose x the patients weight in kg. For example, the ped dose of Ancef is 25 mg/kg. So if you have a 10 kg kid, you just multiply 25x10. 250 mg is your total dose to give.

• Second, convert the amount of drug you are need to give (in mcg or mg) to a volume (number of cc's) to give. This is simply the dose of the drug you are going to give divided by the concentration you have on hand. So if your Ancef comes in a concentration of 100mg/ml. you divide your dose (250) by your concentration (100). 250/100 = 2.5. That the number of cc to give.

Another one: you need to give 1 mcg/kg of fentanyl to a 75kg patient. First, calculate the total dose: 1mcg x 75kg = 75 mcg. Now, you need to covert 75mcg to a volume to give. Your fentanyl is 50mcg/ml. So now divide your dose by your concentration: 75 / 50 = 1.5 ml to give.

That's all there is to it: multiply the ordered dose by the patient's weight, and then divide that number by the concentration on hand. Done.

The above is GREAT if you're giving weight-based medications. Very handy and basically what I do if I must make those calculations myself.

Similar to (ordered/available)*(vehicle).

So if you need to give 2mg of Zofran (4mg/2ml):
(2mg/4mg)*(2ml)=1ml. Therefore, give 1ml.

I like this method because it works for any concentration, you don't have to get it down to blank/1ml. In addition, it's nice because you can use it for pills too:
You need to give 4mg of Zofran ODT. You have 8mg tabs. How many do you give?
(4mg/8mg)*(1 tab)=0.5 tabs.

This is good for those times when you know you need to give a drug dose that's different from unit dose that you have on hand. A couple weeks ago I had to give an antibiotic that we didn't have the particular dose in stock anywhere in the hospital but we did have it available in another dose. I used this formula to determine how much of the antibiotic to give.

Fortunately a lot of the time you only need to give full unit doses...

 

[Carlos Danger]

I explain it the way I do in order to make the procedure of volume calculation appear to be as "math-less" as possible.

This is because I've found people who have a hard time with drug calculations often do so because for whatever reason, they just have some sort of mental block about math and equations. Show them an example of dimensional analysis and they get anxious. And maybe they understand it when you explain it, but then have a hard time remembering how to apply it much later when they need to use it.

I think once people understand that it really only breaks down to 2 steps that each require a single, simple calculation, it makes sense in their minds and is easy to remember because once you understand it what you are doing, it becomes quite obvious in a way that dimensional analysis just isn't to many people.

Of course infusions are a little different, but I really don't think anyone should be running infusions without a pump, in any case.

 

[NomadicMedic]

Of course infusions are a little different, but I really don't think anyone should be running infusions without a pump, in any case.

Yet we do, all the time. Dopamine, epi, and lido are the ones that I seem to use most frequently. Why is it that EMS will buy all kids of goofy toys for the trucks, but hardly anyone carries pumps?

 

[gotbeerz001]

I understand math and have no problem finding answers; however, in the field I prefer a systems such as the Handtevy method for peds and dosing/drip charts since everything seems to go down at 3 am when I am borderline brain-dead.


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[medichopeful]

We use Baxter Sigma Spectrum infusion pumps.

When I was doing nursing clinicals, one of the hospitals I was at was switching over to those. I really like how small they are and how the display is laid out. Easy to see the exact rate from across the room.

Personally I'd prefer pumps that have at least 2 channels or a single cartridge that allows an A (primary) and B (secondary) channel within the cartridge. Then you can run a concurrent secondary drip on a single channel.

The pumps we currently use allow that (Abbott Plum A+3 infusion pumps), but the problem is the setup is huge. Perfect for ICU, not so great for ER (where there's more patient movement). Even so, they're the best pumps I've ever used.

 

[Ethan]

dd x wt. in kg x ds divided by concentration x time in min


dunkin donuts was dripping sugar over their coffee and tea

 

[Mantis Toboggan]

Dimensional analysis practice (if you enjoy that sort of thing):

A jewelry manufacturer is provided 50 lb blocks of silver. One of these blocks will be drawn into a silver wire that is 2.25mm in diameter. If its density measures 10.49 g/cm³, how many feet of wire can be obtained from the silver block?

 

[78mfire]

I would like to thank all of you for the replies. I will have more time after NREMT to figure out what really works best for me but in the mean time I just need a hard and fast way to do it for registry. After that, I'm not going to rely on an app and will work it a lot more but I know our rigs have basic drip rates/calculations cheat sheets. As a Intermediate service, we usually establish an IV TKO or saline lock, depending on if we have a ALS rig intercepting us or transport time. Thanks to all of you again.
I am always open to new and different procedures, within my scope anyway!

 

[Gurby]

Dimensional analysis practice (if you enjoy that sort of thing):

A jewelry manufacturer is provided 50 lb blocks of silver. One of these blocks will be drawn into a silver wire that is 2.25mm in diameter. If its density measures 10.49 g/cm³, how many feet of wire can be obtained from the silver block?

8652.6 feet?

 

[Tigger]

Yet we do, all the time. Dopamine, epi, and lido are the ones that I seem to use most frequently. Why is it that EMS will buy all kids of goofy toys for the trucks, but hardly anyone carries pumps?

Even though our MiniMeds are a pain, they are waaaay better than any sort of gravity infusion. WE buy refurbished models that are two grand plus the yearly service. In the scheme of biomedical devices, that's a good deal.