Math. do you use it in the field?

C

Cody1911

Forum Crew Member
Messages
55
Reaction score
0
Points
0
I was never good at math. I'm reading about title volume etc. These formulas are a bit confusing. I get the concept but do you ever use this in the field? And have to do these formulas in your head? I'm reading on oxygen cylinders and it says like D= 0.16 E=0.28 M=1.56... Etc. It says "example" determine the life of an M cylinder that has a pressure of 2,000 psi displayed on the pressure gauge and flow rate of 10 liters per minute. Then below that it says (2,000 - 200) x 1.56 = 2,808/10 = 280.8 minutes.

What did I just read? And do I need to calculate this stuff within seconds? I am awful at math. I can do pulses... Count for 15 seconds multiply beats by 4. 30 seconds multiply by 2... I can do that. But reading the above shocked me a bit. I know this may come easy to some of you but this looks like something off NASA to me. Am I getting worked up over nothing? What math and calculations do I need to know in the field?

Thanks guys.
 
For the EMT level you most likely will not use any of that. The only kind of actual math I have had to use is to calculate drip rates for the amount of fluids the Doc wants infused during a transport.
 
Got a call once because X was missing. So we had to find for X.
 
You will be fine as a basic, but medic is harder. Yea there are calculators and stuff like that, but you don't get those throughout class and on the national registry.
 
Last edited by a moderator:
I would be surprised if you were even tested over any of that.
 
I think we all use math more often than expected, but it's not all too complex. Figuring out how many pills should be left in a bottle at an OD, or how long transports will take, or the number of minutes until your least favorite dispatcher gets off the desk.
 
emt.dan said:
or the number of minutes until your least favorite dispatcher gets off the desk.
Click to expand...

This is the most important formula that you need to know for EMS hands down.

At the EMT-B level no, you aren't going to use much more than what everyone has described already. At the medic level though there's a fair share of math.

The pediatric dose of Epi is 0.01mg/kg. you have a 10 kg kid, how much Epi are you going to give them in mg? How about mLs of 1:1000 concentration? What about if you're using 1:10000, how many mLs is that?

The pediatric dose for amiodarone is 5 mg/mL. Your patient weighs 22 pounds. What is your dose in mgs? Knowing that your amio comes in 150mg/3mL how many mL do you need to draw for this patient?

Our IM versed dosage is 0.07mg/kg. you've got a 100kg pt, how much do they get in mg? Knowing that your versed comes in 10mg/2mL vials how many mLs do you need to draw up?

Those are examples of math questions on medic tests and things we do every day...ok not pedi arrests but you get my point.

There's three basic formulas that will solve any med math problem you need once you get them locked in.
 
I would say at least once per tour (4 on 4 off) I am calculating how much o2 is in my M tank (back when I worked FT in a 911 and transfer system) Usually for a long transport with a vented pt.
 
Last edited by a moderator:
Cody1911 said:
I was never good at math. I'm reading about title volume etc. These formulas are a bit confusing. I get the concept but do you ever use this in the field? And have to do these formulas in your head? I'm reading on oxygen cylinders and it says like D= 0.16 E=0.28 M=1.56... Etc. It says "example" determine the life of an M cylinder that has a pressure of 2,000 psi displayed on the pressure gauge and flow rate of 10 liters per minute. Then below that it says (2,000 - 200) x 1.56 = 2,808/10 = 280.8 minutes.

What did I just read? And do I need to calculate this stuff within seconds? I am awful at math. I can do pulses... Count for 15 seconds multiply beats by 4. 30 seconds multiply by 2... I can do that. But reading the above shocked me a bit. I know this may come easy to some of you but this looks like something off NASA to me. Am I getting worked up over nothing? What math and calculations do I need to know in the field?

Thanks guys.
Click to expand...

Think about what each number means. 1.56 is simply a constant for that size tank. Memorize it for the tank you use, and don't worry about how they came up with it. 2000-200 gives you the usable pressure from a tank filled with 2000 PSI. You shouldn't dip below 200 PSI, so you have 1800 PSI to "play with." Dividing by 10 is just accounting for the flow rate you're using. Your 2808 number means you have 2808 liters of O2 in the tank, so just by dividing out the LPM number, you're left with minutes as the only unit.

Another tip? Only memorize the calculation constant for your large house tank. The rule for how long your portable tank will last on CPAP or high flow is easy and non-variable. The answer is "not long at all," so get spares quickly. Don't worry about the other medication calculations yet. That will come later in medic school.
 
I just finished my AEMT course. We had to do some med math, mostly converting lbs to kg. This is used for fluid resuscitation, as well as dosing of many of our medications. I struggle with math as well but was just fine. National Registry does not let you use calculators but the tiny bit of math I had to do for one of the stations was with very friendly numbers.
 
The NR usually has a rule of 9s question or 2 as well. I can't think of much else they would test on that required some sort of math.
 
Robb said:
This is the most important formula that you need to know for EMS hands down.

At the EMT-B level no, you aren't going to use much more than what everyone has described already. At the medic level though there's a fair share of math.

The pediatric dose of Epi is 0.01mg/kg. you have a 10 kg kid, how much Epi are you going to give them in mg? How about mLs of 1:1000 concentration? What about if you're using 1:10000, how many mLs is that?

The pediatric dose for amiodarone is 5 mg/mL. Your patient weighs 22 pounds. What is your dose in mgs? Knowing that your amio comes in 150mg/3mL how many mL do you need to draw for this patient?

Our IM versed dosage is 0.07mg/kg. you've got a 100kg pt, how much do they get in mg? Knowing that your versed comes in 10mg/2mL vials how many mLs do you need to draw up?

Those are examples of math questions on medic tests and things we do every day...ok not pedi arrests but you get my point.

There's three basic formulas that will solve any med math problem you need once you get them locked in.
Click to expand...

http://www.remsa.us/policy/4103.pdf
:sad:
 
teedubbyaw said:
I would be surprised if you were even tested over any of that.
Click to expand...

I've had the oxygen tank formula on my NREMT exam. I guessed and moved on.
 
Robb said:
Is it too complicated for medics there to figure it out themselves? :p

Also, your links to that website always throw me for a loop :lol:
Click to expand...

Hahaha. Yep. Our medics are very simple minded haha
 
Or, just function like some medics i know and make everyone 50kg, 70kg or 100kg. I'm always amazed at how many 100kg patients get RSI'ed.

How much etomidate? All of it.
How much Suc? The whole vial.
How much Versed? Yes.

smh.
 
You may see these types of questions on provincial or state level exams. As for if you will use them while you are in service, it just depends on where you are working for the most part. Regardless it's probably important you learn it inside out, just like rule of 9s. Goodluck!
 
DEmedic said:
Or, just function like some medics i know and make everyone 50kg, 70kg or 100kg. I'm always amazed at how many 100kg patients get RSI'ed.

How much etomidate? All of it.
How much Suc? The whole vial.
How much Versed? Yes.

smh.
Click to expand...

I like it. :lol: Holy snowman batman!

I do something similar with IM versed for chemical restraints and seizures just for the fact that 0.07 mg/kg is a pain in the *** to calculate off the top of your head.

With that said, going IV you bet I'm gonna take the time to make sure my math is spot on.
 
This is why our awesome medical director made us "cheat sheets" for both adult and pedi weight conversion and drug calculations with the answer already on it!!! Plus the dosage of the particular drug and it says how much to draw up.
 
You should know how to figure how long the O2 in your tank will last, but you don't necessarily have to use the formula given to figure it out. I can make it easier. Know how much o2 is in your tank when full, say you have a portable D cylinder that holds 340 Liters. If you are running 12 LPM on a patient, divide 340 by 12 and there you go, that's how many minutes you can run a patient on that amount if the tank is full. If its about half full, divide that number by half. If its 1/4, divide by 4, and so on. Its not exact, but should be good enough for government work.

Its good to know how much o2 is on hand running at 15 LPM, IE the worst case scenario. So if say your D is half full, that means you got a little over 10 minutes before it runs out, which is good to know if you are heading out on some remote trail for a patient who wiped out on a 4 wheeler, so you know how much o2 to bring and what to run it at, as its not gonna do them a lot of good to run 15 L with an NRB and have it on empty and your still a while from getting them in the truck with no backup.

Keep in mind you want to keep about 200 PSI in the tank as the safe residual pressure.

Hopefully this didn't make it more confusing, but it seems simple to me.
 
You must log in or register to reply here.
Back
Top