Drug Calculations/IV GTT Rates for EMT Advanced

78mfire

78mfire

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This is my first post, even though I have been "browsing" for some time. I am currently about 4 weeks out from NREMT and well into the clinical portion of the class. My question is this, I am having a rough time nailing down the dosage rate calculations. Its coming to me at a frustratingly slow pace. I always considered myself able to handle conversions but this is a little confusing to me. Would anybody have any hints or suggestions that would help me grasp this a little better. Thanks in advance and I really enjoy this website!!
 
Not sure how we can help. It's basic arithmetic. What are you having trouble with exactly? Drips? Do you have any examples? Where are you getting stuck or lost?

I've written some stuff about it before.

http://emtlife.com/threads/drug-calculation.35378/#post-504817

I know I've written more on it before, but can't find it. I think it was in the 100% directionless. XD Good luck with anyone finding that.

The way I do it can be confusing, but I just stay systematic like with my assessments and ECG interpretation.
 
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Thanks for the reply. Converting grams to milligrams, etc is causing me some trouble.
 
I do that stuff all the time and it's starting to become easier. The drugs that drive me nuts are the ones that are weight based... but I use a simple ratio/proportion formula and it's pretty easy to get the right dose. After that, you just simply have to figure out the drip rate and even that's not too difficult. I do, however, have a trick up my sleeve if I need it: an app that calculates drip rates.
 
The advice is much appreciated, I'm 98.9% sure it's just me over thinking it but I really want to nail this down so I don't second guess myself when it counts!
 
If g<-->mg<-->mcg is really your biggest issue, yea, you are overthinking things and are fine.
 
I had a eureka moment in the shower a few weeks ago... If you are using a 60 gtts set, the number of drops per second = the number of ml's per minute.

So, 1 drop/sec = 1 mL/min. 0.5 drop/sec (ie 1 drop every 2 seconds) = 0.5 mL/min.
 
Gurby said:
I had a eureka moment in the shower a few weeks ago... If you are using a 60 gtts set, the number of drops per second = the number of ml's per minute.

So, 1 drop/sec = 1 mL/min. 0.5 drop/sec (ie 1 drop every 2 seconds) = 0.5 mL/min.
Click to expand...
It's like there was a reason they chose 60 as the base rather than 50...[emoji6]
 
chaz90 said:
It's like there was a reason they chose 60 as the base rather than 50...[emoji6]
Click to expand...

My face when I made this discovery:
121j2r.jpg
 
Gurby said:
I had a eureka moment in the shower a few weeks ago... If you are using a 60 gtts set, the number of drops per second = the number of ml's per minute.

So, 1 drop/sec = 1 mL/min. 0.5 drop/sec (ie 1 drop every 2 seconds) = 0.5 mL/min.
Click to expand...
Excellent!! That seems too easy......
 
Disregard
 
Learn dimensional analysis (https://en.wikipedia.org/wiki/Dimensional_analysis). It's truly the most useful mathematical strategy you'll ever learn. You can use it for anything: drip rates, unit conversion, weight-based drugs, how much of a drug to give, etc.

Plus, it has it's own checks and balances system. If you set it up wrong, as long as you keep track of the unit labels and plug in the right numbers/conversion factors, it will tell you that something is off.

Akulahawk said:
I do that stuff all the time and it's starting to become easier. The drugs that drive me nuts are the ones that are weight based... but I use a simple ratio/proportion formula and it's pretty easy to get the right dose. After that, you just simply have to figure out the drip rate and even that's not too difficult. I do, however, have a trick up my sleeve if I need it: an app that calculates drip rates.
Click to expand...

The pumps we use in the hospital do drip rates for us. I'm totally spoiled. Select the drug, weight, and desired rate, and it automatically plugs it all in for you and sets the ml/hr. There's also the option to enter a volume and an amount of time to infuse it over and it will calculate that out too. Hopefully similar pumps come out for ems in the near future.
 
Gurby said:
I had a eureka moment in the shower a few weeks ago... If you are using a 60 gtts set, the number of drops per second = the number of ml's per minute.

So, 1 drop/sec = 1 mL/min. 0.5 drop/sec (ie 1 drop every 2 seconds) = 0.5 mL/min.
Click to expand...
If you had read my post carefully, you would've figured it out sooner. :D

Aprz said:
If you can convert any other drip set into a 60 gtt drip set, you can easily figure out mL/hr too because whatever gtt/min with a 60 gtt drip set equals the same as mL/hr eg 13 gtt/min with a 60 gtt drip
Click to expand...
http://emtlife.com/threads/the-100-directionless-thread.9773/page-2277#post-164731

Edit: Oh, you are talking about gtt/sec = mL/min. I was thinking of gtt/min = mL/hr. Thinking about mL/min is actually probably more useful. Never thought of this.
 
medichopeful said:
Learn dimensional analysis (https://en.wikipedia.org/wiki/Dimensional_analysis). It's truly the most useful mathematical strategy you'll ever learn. You can use it for anything: drip rates, unit conversion, weight-based drugs, how much of a drug to give, etc.

Plus, it has it's own checks and balances system. If you set it up wrong, as long as you keep track of the unit labels and plug in the right numbers/conversion factors, it will tell you that something is off.

The pumps we use in the hospital do drip rates for us. I'm totally spoiled. Select the drug, weight, and desired rate, and it automatically plugs it all in for you and sets the ml/hr. There's also the option to enter a volume and an amount of time to infuse it over and it will calculate that out too. Hopefully similar pumps come out for ems in the near future.
Click to expand...
If you're able to get the hang of dimensional analysis, it really is a great tool for doing medical calculations. While I can do it, I'm much more familiar with ratio/proportion formulas so I go with what's easier for me. Also, I'm getting spoiled too... our pumps do the same things for us. Sometimes when we've got a question about drip rates for a given drug, we sometimes defer to the pump because that's pre-programmed into the device. That's useful when the drug references are a little fuzzy about specific rates.
 
Akulahawk said:
If you're able to get the hang of dimensional analysis, it really is a great tool for doing medical calculations. While I can do it, I'm much more familiar with ratio/proportion formulas so I go with what's easier for me. Also, I'm getting spoiled too... our pumps do the same things for us. Sometimes when we've got a question about drip rates for a given drug, we sometimes defer to the pump because that's pre-programmed into the device. That's useful when the drug references are a little fuzzy about specific rates.
Click to expand...

It's funny, dimensional analysis is really the only one I can wrap my head around. People have tried to teach me other ways, and I just can't do them. Whatever is easiest and gives the correct answer is the best way to do it! What pumps do you use?
 
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.
 
Remi said:
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.
Click to expand...

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.
 
medichopeful said:
It's funny, dimensional analysis is really the only one I can wrap my head around. People have tried to teach me other ways, and I just can't do them. Whatever is easiest and gives the correct answer is the best way to do it! What pumps do you use?
Click to expand...
We use Baxter Sigma Spectrum infusion pumps. They're not too complicated in that all you're really doing is controlling a gravity drip setup with a pump. That's nice if you're used to doing gravity IVPB infusions and you really want to control the rate... but if you need to do concurrent infusions, you need 2 pumps. 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.
 
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