Med math!

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MiniEMTP

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I'm in training for EMT -P, and it's really simple...yet I'm over-analyzing...on med math.

Does ANYBODY have ANY pointers, simple conversion formulas, and an easier way to convert measurements? (No automatic calculators). HELP! >.<

Thanks!
 
Could you specify exactly what is confusing you about the math? Honestly, med math is really simple because we use the metric system and simple arithmetic. Unfortunately most grammar schools barely teach the metric system which only serves to confuse the hell out of students later on in their education.

If you have a few questions that are stumping you, post them, and I'm sure several of us can talk you through it. Getting it explained in a few ways will give you a chance to pick the explanation you most understand and can retain.
 
You need to get someone to sit down with you and teach you dimensional analysis. You don't need to memorize conversion ratios or any of that. Just simple dimensional analysis is all you need. It's impossible to teach in the format of this forum, so find someone IRL to help you.

If your clinicals get slow, maybe check with one of the nurses you're working with.
 
Learn how to use a conversion factor. (usually taught first week in college general chemistry courses)

One formula you just plug units and numbers into.

When you start working, for the commonly used stuff in your area you will learn the shortcuts and common values.

But in school some of the calculations are hypothetical so learning the shortcuts now may not always give you the right answer.
 
MiniEMTP said:
I'm in training for EMT -P, and it's really simple...yet I'm over-analyzing...on med math.

Does ANYBODY have ANY pointers, simple conversion formulas, and an easier way to convert measurements? (No automatic calculators). HELP! >.<

Thanks!
Click to expand...

There are usually 4 ways to do a calculation (See a dosage calc book), choose the one that is best for you.


Don't forget the simple formulas like [Dose / On Hand] x Vehicle

If you are told to administer 1 mg/kg of a drug to a 150 lb patient:

Take it a step at a time.

1. How many kg is a 150 lb patient? Divide 150 by 2.2
2. Multiply amount in mg x kg

150 / 2.2 = 68 kg

68 kg x 1mg = 68 mg

Dose = 68 mg
 
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Veneficus said:
Learn how to use a conversion factor. (usually taught first week in college general chemistry courses)

One formula you just plug units and numbers into.

When you start working, for the commonly used stuff in your area you will learn the shortcuts and common values.

But in school some of the calculations are hypothetical so learning the shortcuts now may not always give you the right answer.
Click to expand...

Agreed, that system is very useful in dosage calculations. We called that system dimensional analysis in chem class. A good intro link for dimensional analysis use in med math is here.

http://www.alysion.org/dimensional/analysis.htm

There are many other links on DA, just google it...
 
You'll leard DD/DOH, V/T x drip set, etc. in class. After you learn how to calculate a dopamine drip, here's a quick shortcut, one that works out to be exactly the same as the long way:

When mixing 200 mg of dopa in a 250 bag, using a 60 gtt set, the drip rate for 10 mcg/kg/min will be exactly the pt's weight in kg x 0.75. If you need to do 5 mcg/kg/min, halve the drip rate. For 20, just double it. If you're mixing 400mg in a 250 bag, then halve your original answer for 10 mcg/kg/min, and adjust accordingly for 5 mcg or 20.

Here's two sites that may help:

http://nursesaregreat.com/articles/drugcal.htm

http://www.gaems.net/download/drugcalc.pdf
 
If you could tell us exactly what is stumping you, it would make it much easier to give you an appropriate answer.
 
There are only a few formulas you need to memorize.

For example, to know how much of parenteral med to give... just take...

Dose x Vol = mL to give
Total Concentration

IV Infusion (mg/min)

Dose x Vol x Drip Set (60) = gtts/min
Concentration

Dopamine/Dobutamine

dose x weight(kg) x drip set (60) = gtts/min
Concentration (usually 1600mcg)

Know that ml/hr = gtts/min with 60 dropper set.

To find out how much time is left for fluid to infuse... take amount of fluid left / rate infusing (ie 125mL/hr).

Its really much simpler than most ppl make it out to be. Memorize the formulas.. there are a few more... make some laminated cards with em on to keep in your pocket and ur good.
 
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Veneficus said:
Learn how to use a conversion factor. (usually taught first week in college general chemistry courses)

One formula you just plug units and numbers into.

When you start working, for the commonly used stuff in your area you will learn the shortcuts and common values.

But in school some of the calculations are hypothetical so learning the shortcuts now may not always give you the right answer.
Click to expand...


Not looking for so much as a "shortcut" as I am to make learning this stuff easier. I'm stumped on the difference between Dosage on hand, and volume on hand...If i'm not mistaken..

the Dosage is what's in the vial
the VOLUME is what the Dr wants?

this is where i get lost, our book does a really bad job of explaining it. >.<

Thanks everybody for the help!
 
Dose on hand is how many particles of medication in solution you have TOTAL in the container(i.e. how many mgs/mcgs/gms are in the vial). Volume on hand is how much solution you have in container (i.e. how many mls). Desired dose is home much medication you want to give (5mgs, 10mgs, ect). So you need to know how much solution to give (mls) to give to get the desired number of particles (mgs) into the patient. The equation is:

volume on hand x desired dose
__________________________= volume to be administered

dose on hand

Multiply this by 60 to get the gtts a second or mls/hr to run a medicated infusion.
 
It's like this... think how much med do I need to give this patient... what DOSE are they getting. Then think, what is the total VOLUME of medication inside the vial, ampule, carpujet, etc. Then, look at the medication container to see how many TOTAL MILLIGRAMS/MCG are in the container.

DOSE x VOLUME
CONCENTRATION = mL to admin.

Example - A vial of Lasix (40mg in 4mL)
You want to give a patient 80mg IVP.

There are 10mg per 1mL of fluid volume.

The DOSE you want to give is 80mg.

The VOLUME you have is 4mL

The CONCENTRATION is 40mg.

Enter it into your calculator / formula like this....

80mg (DOSE) x 4mL (VOL)
40mg (CONCENTRATION) = 8mL (two vials).
 
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